[Skip to Navigation]
Sign In
Figure. 
Design of the Psychoses in Finland (PIF) Study. A subject could have been selected by several screens. From all those selected by the PIF screen, 692 had final best-estimate diagnoses, and 54 (32 who refused to participate at baseline plus 22 who did not have enough information for diagnostic assessment) were in the nonresponse group. CIDI indicates Composite International Diagnostic Interview; SCID, Structured Clinical Interview for DSM-IV.

Design of the Psychoses in Finland (PIF) Study. A subject could have been selected by several screens. From all those selected by the PIF screen, 692 had final best-estimate diagnoses, and 54 (32 who refused to participate at baseline plus 22 who did not have enough information for diagnostic assessment) were in the nonresponse group. CIDI indicates Composite International Diagnostic Interview; SCID, Structured Clinical Interview for DSM-IV.

Table 1. Overlap of Different Screens in the PIF Study*
Overlap of Different Screens in the PIF Study*
Table 2. The Best-Estimate DSM-IV Diagnoses of the Population With Screen-Positive Findings
The Best-Estimate DSM-IV Diagnoses of the Population With Screen-Positive Findings
Table 3. Lifetime Prevalence Estimates of DSM-IV Psychotic and BPI Disorders*
Lifetime Prevalence Estimates of DSM-IV Psychotic and BPI Disorders*
Table 4. Prevalences of Psychotic Disorders by Age Groups and Sex
Prevalences of Psychotic Disorders by Age Groups and Sex
Table 5. Subjects With a Diagnosis of Psychotic Disorder Found by Specific Screens in the PIF Study
Subjects With a Diagnosis of Psychotic Disorder Found by Specific Screens in the PIF Study
Table 6. Concordance Between the Screens and the DSM-IV Diagnoses of Any Psychotic Disorders in the PIF Study
Concordance Between the Screens and the DSM-IV Diagnoses of Any Psychotic Disorders in the PIF Study
1.
Saha  SChant  DWelham  JMcGraath  J A systematic review of the prevalence of schizophrenia.  PLoS Med 2005;2e141 June 15, 2005PubMedGoogle ScholarCrossref
2.
Kessler  RCBirnbaum  HDemler  OFalloon  IRGagnon  EGuyer  MHowes  MJKendler  KSShi  LWalters  EWu  EQ The prevalence and correlates of nonaffective psychosis in the National Comorbidity Survey Replication (NCS-R).  Biol Psychiatry 2005;58668- 676PubMedGoogle ScholarCrossref
3.
van Os  JHanssen  MBijl  RVVollebergh  W Prevalence of psychotic disorder and community level of psychotic symptoms: an urban-rural comparison.  Arch Gen Psychiatry 2001;58663- 668PubMedGoogle ScholarCrossref
4.
Kendler  KSGallagher  TJAbelson  JMKessler  RC Lifetime prevalence, demographic risk factors, and diagnostic validity of nonaffective psychosis as assessed in a US community sample: the National Comorbidity Survey.  Arch Gen Psychiatry 1996;531022- 1031PubMedGoogle ScholarCrossref
5.
Weissman  MMLeaf  PJTischler  GLBlazer  DGKarno  MBruce  MLFlorio  LP Affective disorders in five United States communities.  Psychol Med 1988;18141- 153PubMedGoogle ScholarCrossref
6.
Kessler  RCMcGonagle  KAZhao  SNelson  CBHughes  MEshleman  SWittchen  HUKendler  KS Lifetime and 12-month prevalence of DSM-III-R psychiatric disorders in the United States: results from the National Comorbidity Survey.  Arch Gen Psychiatry 1994;518- 19PubMedGoogle ScholarCrossref
7.
Bijl  RVRavelli  Avan Zessen  G Prevalence of psychiatric disorder in the general population: results of the Netherlands Mental Health Survey and Incidence Study (NEMESIS).  Soc Psychiatry Psychiatr Epidemiol 1998;33581- 586PubMedGoogle ScholarCrossref
8.
ten Have  MVollenberg  WBija  RNolen  WA Bipolar disorder in the general population in the Netherlands (prevalence, consequences and care utilisation): results from the Netherlands Mental Health Survey and Incidence Study (NEMESIS).  J Affect Disord 2002;68203- 213PubMedGoogle ScholarCrossref
9.
Kessler  RCChiu  WTDemler  OMerikangas  KRWalters  EE Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication.  Arch Gen Psychiatry 2005;62617- 627PubMedGoogle ScholarCrossref
10.
Grant  BFStinson  FSHasin  DSDawson  DAChou  SPRuan  WJHuang  B Prevalence, correlates, and comorbidity of bipolar I disorder and axis I and II disorders: results from the National Epidemiologic Survey on Alcohol and Related Conditions.  J Clin Psychiatry 2005;661205- 1215PubMedGoogle ScholarCrossref
11.
Torrey  EF Prevalence studies in schizophrenia.  Br J Psychiatry 1987;150598- 608PubMedGoogle ScholarCrossref
12.
Lehtinen  VJoukamaa  MLahtela  KRaitasalo  RJyrkinen  EMaatela  JAromaa  A Prevalence of mental disorders among adults in Finland: basic results from the Mini Finland Health Survey.  Acta Psychiatr Scand 1990;81418- 425PubMedGoogle ScholarCrossref
13.
Robins  LNedRegier  DAed Psychiatric Disorders in America.  New York, NY Free Press 1991;
14.
Angst  J The emerging epidemiology of hypomania and bipolar II disorder.  J Affect Disord 1998;50143- 151PubMedGoogle ScholarCrossref
15.
Andreasen  NCCarpenter  WT  Jr Diagnosis and classification of schizophrenia.  Schizophr Bull 1993;19199- 214PubMedGoogle ScholarCrossref
16.
Andreasen  NC The evolving concept of schizophrenia: from Kraepelin to the present and future.  Schizophr Res 1997;28105- 109PubMedGoogle ScholarCrossref
17.
Tohen  MAngst  J Epidemiology of bipolar disorder. Tsuang  MTTohen   M eds Psychiatric Epidemiology. 2nd New York, NY John Wiley & Sons Inc 2002;427- 444Google Scholar
18.
Waraich  PGoldner  EMSomers  JMHsu  L Prevalence and incidence studies of mood disorders: a systematic review of the literature.  Can J Psychiatry 2004;49124- 138PubMedGoogle Scholar
19.
Regeer  EJten Have  MRosso  MLHakkaart-van Roijen  LVollebergh  WNolen  WA Prevalence of bipolar disorder in the general population: a reappraisal study of the Netherlands Mental Health Survey and Incidence Study.  Acta Psychiatr Scand 2004;110374- 382PubMedGoogle ScholarCrossref
20.
Jablensky  A Schizophrenia: recent epidemiologic issues.  Epidemiol Rev 1995;1710- 20PubMedGoogle Scholar
21.
Kessler  RCLittle  RJGroves  RM Advances in strategies for minimizing and adjusting for survey nonresponse.  Epidemiol Rev 1995;17192- 204PubMedGoogle Scholar
22.
Allgulander  C Psychoactive drug use in a general population sample, Sweden: correlates with perceived health, psychiatric diagnoses, and mortality in an automated record-linkage study.  Am J Public Health 1989;791006- 1010PubMedGoogle ScholarCrossref
23.
Bland  RCOrn  HNewman  SC Lifetime prevalence of psychiatric disorders in Edmonton.  Acta Psychiatr Scand Suppl 1988;33824- 32PubMedGoogle ScholarCrossref
24.
Spengler  PAWittchen  H-U Procedural validity of standardized symptom questions for the assessment of psychotic symptoms: a comparison of the DIS with two clinical methods.  Compr Psychiatry 1988;29309- 322PubMedGoogle ScholarCrossref
25.
Helzer  JERobins  LNMcEvoy  LTSpitznagel  E A comparison of clinical and diagnostic interview schedule diagnoses.  Arch Gen Psychiatry 1985;42657- 666PubMedGoogle ScholarCrossref
26.
Östling  SSkoog  I Psychotic symptoms and paranoid ideation in a nondemented population-based sample of the very old.  Arch Gen Psychiatry 2002;5953- 59PubMedGoogle ScholarCrossref
27.
Kessler  RCRubinow  DRHolmes  CAbelson  JMZhao  S The epidemiology of DSM-III-R bipolar I disorder in a general population survey.  Psychol Med 1997;271079- 1089PubMedGoogle ScholarCrossref
28.
Bebbington  PNayani  T The psychosis screening questionnaire.  Int J Methods Psychiatr Res 1995;511- 19Google Scholar
29.
Aromaa  AedKoskinen  Sed Health and functional capacity in Finland: baseline results of the Health 2000 Health Examination Survey.  Helsinki, Finland National Public Health Institute 2004; Publication B12/2004http://www.ktl.fi/terveys2000/index.uk.htmlAugust 8, 2005
30.
Wittchen  H-UPfister  H DIA-X-Interviews: Manual für screening-verfahren und Interview; Interviewheft Längsschnittuntersuchung (DIA-X-Lifetime); Ergänzungsheft (DIAX-Lifetime); Interviewheft Querschnittuntersuchung (DIA-X-12 Monate); Ergänzungsheft (DIA-X-12 Monate); PC-Programm zur Durchführung des Interviews (Längs- und Querschnittuntersuchung).  Frankfurt, Germany Swets and Zeitlinger 1997; Auswertungsprogramm
31.
Pirkola  SPIsometsä  ESuvisaari  JAro  HJoukamaa  MPoikolainen  KKoskinen  SAromaa  ALönnqvist  JK DSM-IV mood-, anxiety- and alcohol use disorders and their comorbidity in the Finnish general population: results from the Health 2000 Study.  Soc Psychiatry Psychiatr Epidemiol 2005;401- 10PubMedGoogle ScholarCrossref
32.
First  MBAnthony  JCTepper  SDryman  A Structured Clinical Interview for DSM-IV Axis I Disorders, Research Version, Nonpatient Edition (SCID-I/NP).  New York Biometrics Research, New York State Psychiatric Institute1997;
33.
Kuoppasalmi  KLönnqvist  JPylkkänen  KHuttunen  M Classification of mental disorders in Finland: a comparison of the Finnish classification of mental disorders in 1987 with DSM-III-R.  Psychiatr Fenn 1989;2065- 81Google Scholar
34.
American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision.  Washington, DC American Psychiatric Association 2000;
35.
SAS Institute Inc, SAS Version 8.02.  Cary, NC SAS Institute Inc 1999;
36.
Research Triangle Institute, SUDAAN Language Manual, Release 9.0.0.  Research Triangle Park, NC Research Triangle Institute 2004;
37.
Jacobi  FWittchen  HUHolting  CHofler  MPfister  HMuller  NLieb  R Prevalence, co-morbidity and correlates of mental disorders in the general population: results from the German Health Interview and Examination Survey (GHS).  Psychol Med 2004;34597- 611PubMedGoogle ScholarCrossref
38.
Wittchen  HUEssau  CAvon Zerssen  DKrieg  JCZaudig  M Lifetime and six-month prevalence of mental disorders in the Munich Follow-Up Study.  Eur Arch Psychiatry Clin Neurosci 1992;241247- 258PubMedGoogle ScholarCrossref
39.
Canino  GJBird  HRShrout  PERubio-Stipec  MBravo  MMartinez  RSesman  MGuevara  LM The prevalence of specific psychiatric disorders in Puerto Rico.  Arch Gen Psychiatry 1987;44727- 735PubMedGoogle ScholarCrossref
40.
McGorry  PDSingh  BSConnell  SMcKenzie  DVan Riel  RJCopolov  DL Diagnostic concordance in functional psychosis revisited: a study of inter-relationships between alternative concepts of psychotic disorder.  Psychol Med 1992;22367- 378PubMedGoogle ScholarCrossref
41.
Lehtinen  VJoukamaa  MJyrkinen  TLahtela  KRaitasalo  RMaatela  JAromaa  A Mental Health and Mental Disorders in the Finnish Adult Population.  Turku and Helsinki, Finland Social Insurance Institution 1991;
42.
Isohanni  MJones  PBMoilanen  KRantakallio  PVeijola  JOja  HKoiranen  MJokelainen  JCroudace  TJärvelin  M Early developmental milestones in adult schizophrenia and other psychoses: a 31-year follow-up of the Northern Finland 1966 Birth Cohort.  Schizophr Res 2001;521- 19PubMedGoogle ScholarCrossref
43.
Hovatta  ITerwilliger  JDLichtermann  DMäkikyrö  TSuvisaari  JPeltonen  LLönnqvist  J Schizophrenia in the genetic isolate of Finland.  Am J Med Genet 1997;74353- 360PubMedGoogle ScholarCrossref
44.
McGrath  JSaha  SWelham  JEl Saadi  OMacCauley  CChant  D A systematic review of the incidence of schizophrenia: the distribution of rates and the influence of sex, urbanicity, migrant status and methodology.  BMC Med 2004;213PubMedGoogle ScholarCrossref
45.
Aleman  AKahn  RSSelten  JP Sex differences in the risk of schizophrenia: evidence from meta-analysis.  Arch Gen Psychiatry 2003;60565- 571PubMedGoogle ScholarCrossref
46.
Joukamaa  MHeliövaara  MKnekt  PAromaa  ARaitasalo  RLehtinen  V Mental disorders and cause-specific mortality.  Br J Psychiatry 2001;179498- 502PubMedGoogle ScholarCrossref
47.
Heilä  HHaukka  JSuvisaari  JLönnqvist  J Mortality among patients with schizophrenia and reduced psychiatric hospital care.  Psychol Med 2005;35725- 732PubMedGoogle ScholarCrossref
48.
Salokangas  RK First-contact rate for schizophrenia in community psychiatric care: consideration of the oestrogen hypothesis.  Eur Arch Psychiatry Clin Neurosci 1993;242337- 346PubMedGoogle ScholarCrossref
49.
Coryell  WLavori  PEndicott  JKeller  MVanEerdewegh  M Outcome in schizoaffective, psychotic, and nonpsychotic depression: course during a six- to 24-month follow-up.  Arch Gen Psychiatry 1984;41787- 791PubMedGoogle ScholarCrossref
50.
Kendler  KS Demography of paranoid psychosis (delusional disorder): a review and comparison with schizophrenia and affective illness.  Arch Gen Psychiatry 1982;39890- 902PubMedGoogle ScholarCrossref
51.
Copeland  JRDewey  MEScott  AGilmore  CLarkin  BACleave  NMcCracken  CFMcKibbin  PE Schizophrenia and delusional disorder in older age: community prevalence, incidence, comorbidity, and outcome.  Schizophr Bull 1998;24153- 161PubMedGoogle ScholarCrossref
52.
Tsuang  MTLevitt  JJSimpson  JC Schizoaffective disorder. Hirsch   SRWeinberger  DReds Schizophrenia. 2nd Oxford, England Blackwell Science Ltd 2003;46- 57Google Scholar
53.
Scully  PJOwens  JMKinsella  AWaddington  JL Schizophrenia, schizoaffective and bipolar disorder within an epidemiologically complete, homogeneous population in rural Ireland: small area variation in rate.  Schizophr Res 2004;67143- 155PubMedGoogle ScholarCrossref
54.
Singh  SPBurns  TAmin  SJones  PBHarrison  G Acute and transient psychotic disorders: precursors, epidemiology, course and outcome.  Br J Psychiatry 2004;185452- 459PubMedGoogle ScholarCrossref
55.
Pini  Sde Queiroz  VPagnin  DPezawas  LAngst  JCassano  GBWittchen  HU Prevalence and burden of bipolar disorders in European countries.  Eur Neuropsychopharmacol 2005;15425- 434PubMedGoogle ScholarCrossref
56.
Taiminen  TRanta  KKarlsson  HLauerma  HLeinonen  KMWallenius  EKaljonen  ASalokangas  RKR Comparison of clinical and best-estimate research DSM-IV diagnoses in a Finnish sample of first-admission psychosis and severe affective disorder.  Nord J Psychiatry 2001;55107- 111PubMedGoogle ScholarCrossref
57.
Mantere  OSuominen  KLeppamäki  SValtonen  HArvilommi  PIsometsä  E The clinical characteristics of DSM-IV bipolar I and II disorders: baseline findings from the Jorvi Bipolar Study (JoBS).  Bipolar Disord 2004;6395- 405PubMedGoogle ScholarCrossref
58.
Väisänen  E Psychiatric Disorders in Finland: A Comparative Study With Special Reference to Geographical and Social Factors [in Finnish, with English summary].  Helsinki, Finland Publications of the Social Insurance Institution 1975;
59.
Veijola  JRäsänen  PIsohanni  MTiihonen  J Low incidence of mania in northern Finland.  Br J Psychiatry 1996;168520- 521PubMedGoogle ScholarCrossref
60.
Räsänen  PTiihonen  JHakko  H The incidence and onset-age of hospitalized bipolar affective disorder in Finland.  J Affect Disord 1998;4863- 68PubMedGoogle ScholarCrossref
61.
Kieseppä  TPartonen  THaukka  JKaprio  JLönnqvist  J High concordance of bipolar I disorder in a nationwide sample of twins.  Am J Psychiatry 2004;1611814- 1821PubMedGoogle ScholarCrossref
62.
Johnson  JHorwarth  EWeissman  MM The validity of major depression with psychotic features based on a community study.  Arch Gen Psychiatry 1991;481075- 1081PubMedGoogle ScholarCrossref
63.
Ohayon  MMSchatzberg  AF Prevalence of depressive episodes with psychotic features in the general population.  Am J Psychiatry 2002;1591855- 1861PubMedGoogle ScholarCrossref
64.
Cantwell  RBrewin  JGlazebrook  CDalkin  TFox  RMedley  IHarrison  G Prevalence of substance misuse in first-episode psychosis.  Br J Psychiatry 1999;174150- 153PubMedGoogle ScholarCrossref
65.
Virtanen  ASalaspuro  MPartanen  AKaukonen  OKinnunen  A 2004 National report to the EMCDDA by the Finnish National Focal point. Drugs in Finland Web site.http://www.stakes.fi/verkkojulk/January 24, 2005
66.
Ritchie  KArtero  SBeluche  IAncelin  MLMann  ADupuy  AMMalafosse  ABoulenger  JP Prevalence of DSM-IV psychiatric disorder in the French elderly population.  Br J Psychiatry 2004;184147- 152PubMedGoogle ScholarCrossref
67.
Isohanni  MMäkikyrö  TMoring  JRäsänen  PHakko  HPartanen  UKoiranen  MJones  P A comparison of clinical and research DSM-III-R diagnoses of schizophrenia in a Finnish national birth cohort: clinical and research diagnoses of schizophrenia.  Soc Psychiatry Psychiatr Epidemiol 1997;32303- 308PubMedGoogle ScholarCrossref
68.
Jablensky  AMcGrath  JHerrman  HCastle  DGureje  OEvans  MCarr  VMorgan  VKorten  AHarvey  C Psychotic disorders in urban areas: an overview of the Study on Low Prevalence Disorders.  Aust N Z J Psychiatry 2000;34221- 236PubMedGoogle ScholarCrossref
69.
Kendler  KSMcGuire  MGruenberg  AMO’Hare  ASpellman  MWalsh  D The Roscommon Family Study, I: methods, diagnosis of probands, and risk of schizophrenia in relatives.  Arch Gen Psychiatry 1993;50527- 540PubMedGoogle ScholarCrossref
70.
King  MCoker  ELeavey  GHoare  AJohnson-Sabine  E Incidence of psychotic illness in London: comparison of ethnic groups.  BMJ 1994;3091115- 1119PubMedGoogle ScholarCrossref
71.
McNaught  ASJeffreys  SEHarvey  CAQuayle  ASKing  MBBird  AS The Hampstead Schizophrenia Survey 1991, II: incidence and migration in inner London.  Br J Psychiatry 1997;170307- 311PubMedGoogle ScholarCrossref
72.
Arajärvi  RSuvisaari  JSuokas  JSchreck  MHaukka  JHintikka  JPartonen  TLönnqvist  J Prevalence and diagnosis of schizophrenia based on register, case record and interview data in an isolated Finnish birth cohort born 1940-1969.  Soc Psychiatry Psychiatr Epidemiol 2005;40808- 816PubMedGoogle ScholarCrossref
73.
Suvisaari  JMHaukka  JKTanskanen  AJLönnqvist  JK Decline in the incidence of schizophrenia in Finnish cohorts born from 1954 to 1965.  Arch Gen Psychiatry 1999;56733- 740PubMedGoogle ScholarCrossref
74.
Kennedy  NEveritt  BBoydell  JVan Os  JJones  PBMurray  RM Incidence and distribution of first-episode mania by age: results from a 35-year study.  Psychol Med 2005;35855- 863PubMedGoogle ScholarCrossref
Original Article
January 2007

Lifetime Prevalence of Psychotic and Bipolar I Disorders in a General Population

Author Affiliations

Author Affiliations: Departments of Mental Health and Alcohol Research (Drs Perälä, Suvisaari, Saarni, Kuoppasalmi, Isometsä, Pirkola, Partonen, Tuulio-Henriksson, Hintikka, Kieseppä, and Lönnqvist) and Health and Functional Capacity (Drs Härkänen and Koskinen), National Public Health Institute, Department of Psychiatry, University of Helsinki (Drs Isometsä, Kieseppä, and Lönnqvist), and Health and Social Services Division, National Research and Development Centre for Welfare and Health (Dr Pirkola), Helsinki, Finland; Tampere School of Public Health, University of Tampere (Dr Suvisaari), and Department of Psychiatry, Tampere University Hospital (Dr Hintikka), Tampere, Finland; and Department of Psychiatry, Päijät-Häme Central Hospital, Lahti, Finland (Dr Hintikka).

Arch Gen Psychiatry. 2007;64(1):19-28. doi:10.1001/archpsyc.64.1.19
Abstract

Context  Recent general population surveys of psychotic disorders have found low lifetime prevalences. However, this may be owing to methodological problems. Few studies have reported the prevalences of all specific psychotic disorders.

Objective  To provide reliable estimates of the lifetime prevalences of specific psychotic disorders.

Design  General population survey.

Setting and Participants  A nationally representative sample of 8028 persons 30 years or older was screened for psychotic and bipolar I disorders using the Composite International Diagnostic Interview, self-reported diagnoses, medical examination, and national registers. Those selected by the screens were then reinterviewed with the Structured Clinical Interview for DSM-IV. Best-estimate DSM-IV diagnoses were formed by combining the interview and case note data. Register diagnoses were used to estimate the effect of the nonresponders.

Main Outcome Measures  Diagnosis of any psychotic or bipolar I disorder according to the DSM-IV criteria.

Results  The lifetime prevalence of all psychotic disorders was 3.06% and rose to 3.48% when register diagnoses of the nonresponder group were included. Lifetime prevalences were as follows: 0.87% for schizophrenia, 0.32% for schizoaffective disorder, 0.07% for schizophreniform disorder, 0.18% for delusional disorder, 0.24% for bipolar I disorder, 0.35% for major depressive disorder with psychotic features, 0.42% for substance-induced psychotic disorders, and 0.21% for psychotic disorders due to a general medical condition. The National Hospital Discharge Register was the most reliable of the screens (κ = 0.80). Case notes supplementing the interviews were essential for specific diagnoses of psychotic disorders.

Conclusions  Multiple sources of information are essential for accurate estimation of lifetime prevalences of psychotic disorders. The use of comprehensive methods reveals that their lifetime prevalence exceeds 3%.

The lifetime prevalence (LTP) of both schizophrenia and bipolar I (BPI) disorder is often assumed to be about 1%. However, in a recent systematic review, the median LTP of schizophrenia was only 0.4%.1 Recent population-based surveys in particular have found considerably lower LTPs of schizophrenia2-4 and higher rates of BPI disorder5-10 than in many older studies.11-14 Potential reasons for this include narrowing of the diagnostic criteria for schizophrenia and parallel broadening of those for affective disorders after the introduction of the DSM-III,15-17 different diagnostic instruments,18,19 and increasing problems at the levels of case finding and ascertainment.20 Survey response rates have fallen in recent decades,21 and people with psychotic disorders are less likely than others to participate in mental health surveys.2,22,23 Personal interviews may also generate false-negative findings owing to inadequate probing or denial of previous psychotic symptoms.2,4,24,25 Consistent with this, prevalences of schizophrenia have been higher in studies in which registers or case notes have been available12,26 compared with studies relying only on interviews. Little population-based research has been conducted on other psychotic disorders.

Diagnoses of psychotic and bipolar disorders from structured interviews conducted by lay interviewers have not been congruent with classification by psychiatrists.2,4,19,27 To provide more reliable and valid estimates of psychotic disorder rates, 2-stage procedures for case identification have been used. The problem with the 2-stage procedure is that no established method is available for screening individuals with psychotic disorders in the general population. Those methods that have been developed are usually sensitive and specific, but their positive predictive value is poor because of the low prevalence of psychosis in the general population.28

The Psychoses in Finland (PIF) Study is based on the Health 2000 Study, a Finnish general population survey.29 The aims of the PIF Study were to obtain the most accurate possible estimates of LTP of all psychotic and BPI disorders in the general population by gathering extensive information from semistructured interviews, registers, and case notes and to compare different screening methods for detecting psychotic disorders in the general population.

Methods
Study design

The Health 2000 Study is based on a nationally representative sample of 8028 persons 30 years and older (http://www.ktl.fi/terveys2000/index.uk.html29). A 2-stage stratified cluster sampling procedure was used to select 80 areas (including 160 municipalities) from Finland. All 15 of the biggest towns were included, and the remaining 65 health care districts were sampled as clusters by using the probability proportional to population size sampling. From these areas, a random sample of 8028 individuals 30 years and older was finally drawn from the National Population Register. Those 80 years or older were oversampled (2:1). Institutionalized and homeless persons were also included. The field work took place from 2000 through 2001 and consisted of a home interview and health examination at the local health care center or, for those unable to attend, a condensed interview and health examination at home or in an institution. The response rate was 93.00%.29 The health examination included a detailed medical examination, a part of which a physician assessed whether the subject had a possible or a definite psychotic disorder. Mental disorders were also assessed by the Composite International Diagnostic Interview (CIDI).30,31

The Health 2000 Study sample was screened for psychotic disorders, and those with positive findings were reassessed using the research version of the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I).32 Case notes were also obtained, and the final diagnostic assessment combined the interview and case note data. This reassessment of psychotic disorders formed the basis of the PIF Study. The ethics committees of the National Public Health Institute and the Hospital District of Helsinki and Uusimaa, Helsinki, approved the Health 2000 Survey and the PIF reassessment. Participants provided written informed consent.

Pif screen

The PIF psychosis screen consisted of several elements. If any screen findings were positive, the person was invited for a reinterview. The positive screen findings included the following:

  1. The Health 2000 Study examination found self-reported psychotic disorders (n = 77) or possible or definite psychotic disorders as assessed by a physician (n = 45).

  2. The CIDI section F screen for bipolar I disorder detected a lifetime episode of elevated mood lasting at least 4 days plus at least 3, not necessarily concurrent, CIDI manic symptoms (n = 124); the section G screen for positive psychotic symptoms detected any clinically relevant positive psychotic symptom (ie, the symptom interfered with normal life or the person had discussed it with a health care professional), or at least 3 symptoms regardless of clinical relevance that may have occurred during the subject's lifetime (n = 238); the section P screen for other psychotic symptoms detected symptoms of positive formal thought disorder, negative symptoms, behavior that suggests the person is having hallucinations, or catatonic symptoms (n = 93). After the interview, the interviewer may have recorded comments on the interview (CIDI comments section). If the subject was not selected by any of the other screens, but the interviewer comments were indicative of psychotic disorder, the individual was selected for reinterview (n = 4). All CIDI screens also included subjects whose symptoms were caused by physical illness, medication, or substance abuse.

  3. Registers included hospital treatment because of a diagnosis of any psychotic or bipolar disorder (National Hospital Discharge Register; n = 238), free medication for severe psychotic and other severe mental disorders (Medication Reimbursement Register of the Finnish Social Insurance Institution; n = 211), and disability pension because of any psychotic disorder, bipolar disorder, or major depressive disorder (MDD) (Pension Register of the Finnish Centre for Pensions; n = 180).

For screening BPI disorder, we also used the Finnish National Prescription Register of the National Insurance Institution. All subjects not selected by any other screen who had used lithium or mood-stabilizing anticonvulsants from 1996 through 2002, but without a diagnosis of epilepsy or other somatic disorder to account for the medication, were also selected for reinterview (n = 36).

Information on psychotic disorders was obtained from the registers from 1969 through 2002. In Finland, psychiatric diagnoses were coded according to the International Classification of Diseases, Eighth Revision before 1987; according to the Finnish version of the International Classification of Diseases, Ninth Revision, from 1987 until 1995, using the criteria of the DSM-III-R33; and according to the International Statistical Classification of Diseases, 10th Revision (ICD-10), since 1996. The National Hospital Discharge Register covers all hospitals in Finland. It lists dates and diagnoses for each inpatient and day-patient stay. The Pension Register includes the start date and primary diagnoses for all disability pensions. The Medication Reimbursement Register lists persons receiving free outpatient medication. The Prescription Register records all reimbursed purchases of drugs in Finland.

Mental health assessment

The PIF participants were reinterviewed from 2002 through 2004. Subjects selected only via the National Hospital Discharge Register were contacted through the person responsible for the treatment, usually their general practitioner or the psychiatrist from the local mental health care unit. Those selected only by other registers were contacted through the institutions in question.

The study protocol began with a neuropsychological assessment, followed by the SCID-I.32 The Global Assessment of Functioning and the Social and Occupational Functioning Assessment Scale were completed using structured questions.

Experienced research nurses or psychologists conducted the protocol. They attended a 1-month training session, with regular follow-up training and reliability sessions. All SCID-I findings were reviewed by a clinical supervisor (J.S., T.P., J.H., or T.K.), and final ratings and diagnoses were based on consensus between the interviewer and clinical supervisor.

Case notes

For the final diagnostic assessment, all case notes from the hospital and outpatient treatments were collected with the approval of the Finnish Ministry of Social Affairs and Health, excluding the subjects who had refused participation in the Health 2000 Study. Case notes were compiled first using information from the National Hospital Discharge Register and self-reported mental health care contacts, and then from public general medical centers. The aim was to obtain information on all lifetime treatments for all mental health problems.

Best-estimate diagnoses

The final best-estimate diagnoses were made by 3 experienced clinicians (J.P., J.S., and S.I.S.) using DSM-IV-TR criteria.34 Diagnostic evaluation was based on all available, systematically evaluated information from the interview and/or the case records. The first 20 cases were assessed together to ensure consistency between the rating clinicians. Thereafter, the reliability of diagnoses was tested on 136 cases, selected by weighting toward those with a diagnosis of any psychotic disorder or of bipolar disorder in the registers or in the SCID-I, which were rated by all 3 clinicians. The κ values for the 3 rates were 0.89 to 0.92 for schizophrenia, 0.91 to 0.96 for schizophrenia spectrum disorders, 0.74 to 0.91 for all nonaffective psychotic disorders, 0.76 to 0.97 for affective psychotic disorders, and 0.85 to 0.93 for psychotic disorders induced by substances or a general medical condition (GMC). All substance-induced psychotic disorders were reviewed by a senior psychiatrist (K.K.), an expert in this area.

Only definite psychotic disorders were diagnosed. We estimated the LTP of psychotic disorders at the time of the baseline survey. Therefore, subjects with onset of psychotic symptoms after 2001 were considered unaffected.

Population with screen-positive findings

The PIF screen selected 9.29% of the Health 2000 Study population (Figure). Thirty-two subjects in the screened population had refused to participate in the Health 2000 Study at baseline, and only register information was available for them. Forty-six had died before our contact, but we obtained case notes for them. Of the remaining population, 66.3% were successfully reinterviewed. The final diagnostic assessment involved 692 subjects (92.8%) of the screened population.

Control subjects

To obtain population reference data for the methods used in the assessment and to validate the PIF screen, 174 controls were randomly selected for reinterview from all those who had attended any phase of the baseline study. Some of the controls (n = 24) were later selected also by the PIF screen and were included only in the screened population in the analysis. Of the remaining 150 controls with screen-negative findings, 66.0% were reinterviewed, and the final diagnostic assessment involved 140 (93.3%) of the controls.

Statistical analysis

The data were weighted to adjust for differential probabilities of selection in the sampling design and for correlation within clusters and to correct for the oversampling in the group 80 years or older. We used SAS version 8.0235 and SUDAAN version 9.0.036 statistical software for the analyses.

Prevalences were estimated by calculating proportions for dichotomous variables, and asymmetric 95% confidence intervals (CIs) for percentages were calculated using the logit transformation.36 Prevalences in different age groups and between sexes were compared using the χ2 statistic for survey design. To estimate the effect of nonresponse, we calculated the prevalences again using register diagnoses for those nonrespondents who had a register diagnosis of psychotic disorders, but only if the exact diagnostic code was available (77.1% of nonrespondents with register diagnosis). Concordances between the screen findings and the DSM-IV final diagnoses were evaluated by calculating the κ, sensitivity, specificity, and positive and negative predictive values. The total number of subjects for each screen included all participants in that particular phase of the baseline study. Subjects in the nonresponse group were excluded.

Results
SCREEN-POSITIVE FINDINGS AND DSM-IV DIAGNOSES

Table 1 presents the number and the overlap of subjects selected by different screens, and Table 2 presents the DSM-IV axis I diagnoses of the screen-positive subjects. Overall, 35.8% had any psychotic disorder. Diagnosis was deferred for 18 subjects, 8 of whom had had psychotic symptoms. Of the 248 subjects with a final diagnosis of any psychotic disorder, 127 (51.2%) attended the SCID-I. A diagnosis could be made in 59.7% of these on the basis of the SCID-I alone, but the remaining 40.3% did not report or remember some important details of their illness. For them, case notes were essential for accurate diagnosis.

Ltp of psychotic and bpi disorders

Lifetime prevalence estimates of psychotic and BPI disorders and their 95% CIs are presented in Table 3. Table 4 presents the LTP estimates for both sexes in different age groups. The LTP was 3.06% for any psychotic disorder, 1.94% for nonaffective psychotic disorders, and 0.59% for affective psychotic disorders. When we used register diagnoses for subjects in the nonresponse group, the prevalences rose to 3.48%, 2.29%, and 0.62%, respectively. If BPI disorder without psychotic features is excluded, the estimates are 2.99% (95% CI, 2.59%-3.43%) for any psychotic disorder and 0.47% (95% CI, 0.34%-0.64%) for affective psychotic disorders, and 3.40% (95% CI, 2.98%-3.89%) and 0.51% (95% CI, 0.37%-0.68%), respectively, when the nonresponse group is included.

Comparison of different screening methods

Table 5 presents the numbers of subjects selected by specific screens as having a lifetime diagnosis of psychotic disorder and their percentages of the total group with the same diagnosis in the study. Of the subjects with nonaffective or affective psychotic disorder, 75.5% to 81.0% were captured by the National Hospital Discharge Register, compared with only 59.4% and 47.8% of the those with psychoses induced by substance use or a GMC, respectively. Only one third of the subjects with nonaffective psychotic disorders or substance-induced psychotic disorder (and an even smaller proportion of these with other psychoses) would have been found by the CIDI psychotic symptoms screen. Section F of the CIDI was able to detect only 25.0% of the subjects with BPI disorder. Of the subjects selected only by the Prescription Register for using anticonvulsants, 1 had psychosis due to GMC and 3 had substance-induced psychoses. None of the 4 selected by the CIDI comment section had a psychotic disorder. One of the controls had a diagnosis of psychotic disorder due to dementia and was included in the total LTP estimates. None of the controls with screen-negative results had functional psychotic disorder.

Table 6 presents the concordance between the different screening methods and the best-estimate diagnoses of psychotic disorders. The κ values were best for registers and lower for other screens. Registers were the most sensitive screens, whereas the sensitivity of other screens was rather poor. The specificity and negative predictive value of all of the screens were comparably high. The positive predictive values of the National Hospital Discharge Register, self-reported psychoses, and psychoses assessed by a physician were good, but the last 2 had low sensitivity.

Comment

The PIF Study is, to our knowledge, the most comprehensive general population survey of the prevalence of psychotic disorders, in terms of diagnostic assessment and diagnostic coverage. Our study is also the first to report the prevalences of specific psychotic disorders separately. Finally, we were able to compare the different screening methods of psychotic disorders.

The LTP of all psychotic disorders was high, at 3.06% and 3.48% when register diagnoses of nonresponders were included. Only 1 survey has obtained a higher estimate,37 but this was based on CIDI diagnoses of possible psychotic disorders, whose reliability is questionable. In our study, the LTPs of nonaffective psychoses and schizophrenia were higher than in most recent general population studies that have used modern community sampling techniques and operational diagnostic criteria.2-4 The LTP of schizophrenia has varied from 0.12% to 1.6%.2-4,12,23,38,39 Older studies have found even higher prevalences, but comparison with them is difficult owing to changes in diagnostic criteria. Concordance between diagnoses made using DSM-III and more recent operational criteria and those using more historical definitions are only modest.40 Previous Finnish studies, all including register data, have found comparably high prevalences of schizophrenia.12,41-43 However, it is likely that the prevalence of schizophrenia in other recent population surveys would also have been considerably higher if the authors had had access to register and case note information.

Consistent with the review by Saha et al,1 there was no sex difference in the prevalence of schizophrenia, which is discordant with the higher incidence44 and morbid risk45 of schizophrenia in men. However, the age at onset of schizophrenia is lower for men and their mortality is higher,46 particularly during the first years after the onset of the disorder.47 On the other hand, most of the late-onset cases are female. Thus, it seems that in our study the inclusion of older women has raised the prevalence in this group, whereas higher mortality among men has lowered the prevalence in men. Congruent with this, the mean age of subjects with schizophrenia was 50 years for men and 56 years for women. Nevertheless, the incidence48 and prevalence41 of schizophrenia among men and women have also been equal in many previous Finnish studies.

There are only a few general population studies of the prevalence of schizoaffective49 and delusional50,51 disorders in community samples. The LTP of schizoaffective disorder was approximately half of that for schizophrenia52 and, as in previous studies,49,53 it was more common in women. The LTP of delusional disorder was 0.18%, whereas previous estimates range from 0.02% to 0.04%.50,51 Delusional disorder was found only in the group 45 years or older. The estimate reported herein is probably still an underestimation: patients are not inclined to seek treatment because of the lack of insight associated with the disorder while they still have a relatively well-preserved functional capacity. Because delusions in this disorder are nonbizarre, it is extremely difficult to assess in a single interview whether they are genuine delusions if no other source of information is available.

Schizophreniform and brief psychotic disorders were rare. With a long enough follow-up, most subjects with a psychotic episode experience relapse. This accords with a 3-year follow-up of subjects with ICD-10 acute and transient psychoses in which the diagnosis remained unchanged in only 34% of the subjects.54

The LTP of BPI disorder was 0.24%, lower than in most previous studies in which the LTP has varied from 0.2% to 3.3%.6-8,10,14,55 However, general population studies using fully structured interviews (CIDI) to diagnose BPI disorder have found LTPs twice as high as studies using other diagnostic instruments.18 This is explainable by the false-positive diagnoses produced by the CIDI.19,27 Overall, our findings and previous ones imply that prevalences of BPI disorder based on fully structured interviews such as the CIDI should be interpreted with caution.19

We screened BPI disorder from multiple sources. However, the LTP may still be conservative. There were probably previously undiagnosed subjects who denied having had manic symptoms in the CIDI.19 Previous manic episodes among subjects with a major depressive episode may also be underdiagnosed in clinical practice.56,57 Those with a diagnosis of nonpsychotic depression in hospitals were not selected for our reassessment, but all subjects with a disability pension or reimbursed medication for MDD were reassessed. Manic symptoms were sometimes poorly described in the case notes. If all subjects who received a diagnosis of bipolar disorder not otherwise specified because of insufficient information had BPI disorder, its prevalence would rise to 0.39%. The inclusion of register diagnoses of BPI disorder for the nonresponse group would lift the prevalence to 0.42%. However, our low prevalence accords with previous Finnish studies.58-61

The LTP of MDD with psychotic features also fell in the lower range of the few previously published studies.62,63 There were no differences between the sex and age groups, which was unexpected because MDD was less common in men and in older age groups.31

Substance-induced psychotic disorders were frequent in men aged 30 to 54 years. Most had alcohol-induced psychotic disorders; the prevalence of other substance-induced psychoses was only 0.03%. Comparisons with previous studies are difficult to make, because substance-induced psychotic disorders are not included in recent general population studies of psychoses. Of first-admission patients with psychotic disorders in the study by Cantwell et al,64 8.4% were substance induced. The higher prevalence of alcohol-induced psychoses in men accords with the higher prevalence of alcohol dependence in men.31 The low prevalence of psychotic disorders caused by substances other than alcohol reflects the low frequency of their use in the Finnish population who are 30 years or older.65

The LTP of psychotic disorders due to a GMC began increasing in the group 65 years or older and was 1.71% among subjects 80 years or older. Most subjects (92.9%) with psychotic disorder due to GMC in the group 80 years or older had dementia. The LTP of psychotic disorders due to a GMC is clearly an underestimation because many somatic diseases are associated with psychotic symptoms that are rarely diagnosed and reported separately. Overall, the prevalence of psychotic disorders was highest in the elderly. This accords with previous studies of the population who were older than 65 years66 or older than 80 years.26

Screening based on multiple sources was essential to achieve the highest possible coverage of subjects with psychotic disorders. Registers were the most important and reliable source of information, as in a previous Finnish study.12 The κ value of 0.80 for the National Hospital Discharge Register, similar to that in a previous Finnish study,67 indicates that, although register information on psychotic disorders is good, it is not excellent for case ascertainment. The lower concordance of other registers was the result of different coding of diagnoses and their inclusion of subjects with MDD. In this study, all other screens added only 25.0% and 13.7% of the subjects with psychotic disorders to those selected by the National Hospital Discharge Register, or all the registers, respectively. Using all other screens except the registers would have located only 52.4% of subjects with psychotic disorders.

Section G of the CIDI has been used to screen for psychotic disorders in recent general population studies of nonaffective psychoses.2-4 Besides producing false-positive results, the section G screen produced a large number of false-negative results. Only 26.6% of subjects with psychotic disorders would have been recognized if the only screen had been CIDI section G, and the prevalence of schizophrenia would have been 0.28%, which is quite similar to that of other studies using the same method.2-4 Thus, the CIDI alone is not sufficient for screening psychotic disorders. The CIDI mania section was equally unreliable, finding only 25.0% of the subjects with BPI disorder. A self-reported or psychotic disorder assessed by a physician produced only a few false-positive cases, ie, the specificity was excellent, supporting previous results.68 However, the sensitivity of these screens was poor.

Obtaining case notes was important for making diagnoses in subjects who did not participate in the SCID-I, but also for accurately making diagnoses in subjects who did participate in it. Previous incidence and family studies of psychoses with access to case notes or to other longitudinal information in addition to semistructured interviews have also been able to ascertain more subjects with psychotic disorders than studies using only interview information.66,69-72

In this study, we were able to overcome many of the methodological problems inherent in general population studies of psychotic disorders. Register information enables estimation of nonresponse to be included in prevalence rates. Although the response rate in the Health 2000 Study was exceptionally high, the prevalence estimate was 12% higher when subjects with a register diagnosis of psychosis in the nonresponse group were included in the calculations. Our study also included homeless subjects. Homelessness is very rare in Finland; our screen identified 2 of the 25 subjects without a permanent address in the entire Health 2000 Study population. Institutionalized persons, another subpopulation often excluded from general population surveys, were included in our study. Being institutionalized was defined as staying in an institution longer than 3 months, and only 14 (5.7%) of the subjects with any psychotic disorder diagnosis fulfilled this definition. However, these findings cannot be generalized to other studies because rates of nonresponse, institutionalization, and homelessness are highly variable.

The exclusion of adults younger than 30 years limits the comparison with previous studies. Among young adults, the incidence of schizophrenia and bipolar disorders is high,73,74 but the prevalence could be lower than in older groups. In terms of overall prevalence, this was probably compensated for by the higher mortality of subjects with psychotic disorders.46,47 However, the inclusion of older groups and exclusion of young adults might also have affected the observed sex differences in disorders other than schizophrenia: patients with late onset, who were predominantly female, raised the prevalence of delusional disorder, psychotic disorder not otherwise specified, and MDD with psychotic features, whereas exclusion of young men lowered the prevalence of substance-induced psychotic disorders.

One particular problem related to the inclusion of the oldest group is that the subjects might not have remembered psychotic symptoms if they had had them decades ago. This recall bias was partially overcome by register data and case notes, which we obtained on a lifetime basis.

The number of cases in many disorders was small and the CIs were large. Our LTP estimates are still conservative because there were probably undetected cases among those nonresponders without a register diagnosis of psychotic disorder and also among Health 2000 Study participants with screen-negative findings. This particularly concerns the milder forms of psychotic disorders. There were also subjects in the diagnosis-deferred category for whom a psychotic disorder was suspected but could not be confirmed. Moreover, the LTP of psychotic disorder not otherwise specified was high, indicating insufficient information to assign a specific diagnosis for some of these subjects. However, our prevalence estimates are high, which suggests that our screen was able to detect most of the subjects with psychotic disorders.

The exact prevalences we report apply only to Finland, a Nordic country with a relatively low immigration rate and no large cities. However, we believe that our prevalence estimates are more accurate than those in previous studies and that screening from nationwide health care registers and use of case note information would have increased the case detection substantially in other general population studies as well.

In conclusion, our results support previous suggestions that multiple sources of information are essential to estimate the LTP of psychotic disorders. Psychotic disorders are among the most severe and impairing conditions; with an LTP exceeding 3%, these disorders are a major public health concern.

Correspondence: Jonna Perälä, MD, Department of Mental Health and Alcohol Research, National Public Health Institute, Mannerheimintie 166, 00300 Helsinki, Finland (jonna.perala@ktl.fi).

Submitted for Publication: November 15, 2005; final revision received February 23, 2006; accepted April 13, 2006.

Financial Disclosure: None reported.

Funding/Support: This study was supported by grants from the Academy of Finland (Dr Lönnqvist), the Stanley Medical Research Institute (Dr Suvisaari), and the Yrjö Jahnsson Foundation (Dr Perälä).

Previous Presentation: This study was presented as an abstract at the 13th Winter Workshop on Schizophrenia Research; February 7, 2006; Davos, Switzerland.

Acknowledgment: We thank Merja Blom, Saara Heusala, Margit Keinänen-Guillaume, Helena Kurru, Pirkko Levon, Liisa Moilanen, and Tuula Mononen for the interviews; Jari Haukka, PhD, and Marjut Schreck for data management; and Satu Kilpeläinen, MSc, Tuula Koski, and Kirsi Niinistö for administrative work. We also thank Arpo Aromaa, MD, PhD, and all the other collaborators in the Health 2000 team and in the national institutions, as well as all of the research subjects.

References
1.
Saha  SChant  DWelham  JMcGraath  J A systematic review of the prevalence of schizophrenia.  PLoS Med 2005;2e141 June 15, 2005PubMedGoogle ScholarCrossref
2.
Kessler  RCBirnbaum  HDemler  OFalloon  IRGagnon  EGuyer  MHowes  MJKendler  KSShi  LWalters  EWu  EQ The prevalence and correlates of nonaffective psychosis in the National Comorbidity Survey Replication (NCS-R).  Biol Psychiatry 2005;58668- 676PubMedGoogle ScholarCrossref
3.
van Os  JHanssen  MBijl  RVVollebergh  W Prevalence of psychotic disorder and community level of psychotic symptoms: an urban-rural comparison.  Arch Gen Psychiatry 2001;58663- 668PubMedGoogle ScholarCrossref
4.
Kendler  KSGallagher  TJAbelson  JMKessler  RC Lifetime prevalence, demographic risk factors, and diagnostic validity of nonaffective psychosis as assessed in a US community sample: the National Comorbidity Survey.  Arch Gen Psychiatry 1996;531022- 1031PubMedGoogle ScholarCrossref
5.
Weissman  MMLeaf  PJTischler  GLBlazer  DGKarno  MBruce  MLFlorio  LP Affective disorders in five United States communities.  Psychol Med 1988;18141- 153PubMedGoogle ScholarCrossref
6.
Kessler  RCMcGonagle  KAZhao  SNelson  CBHughes  MEshleman  SWittchen  HUKendler  KS Lifetime and 12-month prevalence of DSM-III-R psychiatric disorders in the United States: results from the National Comorbidity Survey.  Arch Gen Psychiatry 1994;518- 19PubMedGoogle ScholarCrossref
7.
Bijl  RVRavelli  Avan Zessen  G Prevalence of psychiatric disorder in the general population: results of the Netherlands Mental Health Survey and Incidence Study (NEMESIS).  Soc Psychiatry Psychiatr Epidemiol 1998;33581- 586PubMedGoogle ScholarCrossref
8.
ten Have  MVollenberg  WBija  RNolen  WA Bipolar disorder in the general population in the Netherlands (prevalence, consequences and care utilisation): results from the Netherlands Mental Health Survey and Incidence Study (NEMESIS).  J Affect Disord 2002;68203- 213PubMedGoogle ScholarCrossref
9.
Kessler  RCChiu  WTDemler  OMerikangas  KRWalters  EE Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication.  Arch Gen Psychiatry 2005;62617- 627PubMedGoogle ScholarCrossref
10.
Grant  BFStinson  FSHasin  DSDawson  DAChou  SPRuan  WJHuang  B Prevalence, correlates, and comorbidity of bipolar I disorder and axis I and II disorders: results from the National Epidemiologic Survey on Alcohol and Related Conditions.  J Clin Psychiatry 2005;661205- 1215PubMedGoogle ScholarCrossref
11.
Torrey  EF Prevalence studies in schizophrenia.  Br J Psychiatry 1987;150598- 608PubMedGoogle ScholarCrossref
12.
Lehtinen  VJoukamaa  MLahtela  KRaitasalo  RJyrkinen  EMaatela  JAromaa  A Prevalence of mental disorders among adults in Finland: basic results from the Mini Finland Health Survey.  Acta Psychiatr Scand 1990;81418- 425PubMedGoogle ScholarCrossref
13.
Robins  LNedRegier  DAed Psychiatric Disorders in America.  New York, NY Free Press 1991;
14.
Angst  J The emerging epidemiology of hypomania and bipolar II disorder.  J Affect Disord 1998;50143- 151PubMedGoogle ScholarCrossref
15.
Andreasen  NCCarpenter  WT  Jr Diagnosis and classification of schizophrenia.  Schizophr Bull 1993;19199- 214PubMedGoogle ScholarCrossref
16.
Andreasen  NC The evolving concept of schizophrenia: from Kraepelin to the present and future.  Schizophr Res 1997;28105- 109PubMedGoogle ScholarCrossref
17.
Tohen  MAngst  J Epidemiology of bipolar disorder. Tsuang  MTTohen   M eds Psychiatric Epidemiology. 2nd New York, NY John Wiley & Sons Inc 2002;427- 444Google Scholar
18.
Waraich  PGoldner  EMSomers  JMHsu  L Prevalence and incidence studies of mood disorders: a systematic review of the literature.  Can J Psychiatry 2004;49124- 138PubMedGoogle Scholar
19.
Regeer  EJten Have  MRosso  MLHakkaart-van Roijen  LVollebergh  WNolen  WA Prevalence of bipolar disorder in the general population: a reappraisal study of the Netherlands Mental Health Survey and Incidence Study.  Acta Psychiatr Scand 2004;110374- 382PubMedGoogle ScholarCrossref
20.
Jablensky  A Schizophrenia: recent epidemiologic issues.  Epidemiol Rev 1995;1710- 20PubMedGoogle Scholar
21.
Kessler  RCLittle  RJGroves  RM Advances in strategies for minimizing and adjusting for survey nonresponse.  Epidemiol Rev 1995;17192- 204PubMedGoogle Scholar
22.
Allgulander  C Psychoactive drug use in a general population sample, Sweden: correlates with perceived health, psychiatric diagnoses, and mortality in an automated record-linkage study.  Am J Public Health 1989;791006- 1010PubMedGoogle ScholarCrossref
23.
Bland  RCOrn  HNewman  SC Lifetime prevalence of psychiatric disorders in Edmonton.  Acta Psychiatr Scand Suppl 1988;33824- 32PubMedGoogle ScholarCrossref
24.
Spengler  PAWittchen  H-U Procedural validity of standardized symptom questions for the assessment of psychotic symptoms: a comparison of the DIS with two clinical methods.  Compr Psychiatry 1988;29309- 322PubMedGoogle ScholarCrossref
25.
Helzer  JERobins  LNMcEvoy  LTSpitznagel  E A comparison of clinical and diagnostic interview schedule diagnoses.  Arch Gen Psychiatry 1985;42657- 666PubMedGoogle ScholarCrossref
26.
Östling  SSkoog  I Psychotic symptoms and paranoid ideation in a nondemented population-based sample of the very old.  Arch Gen Psychiatry 2002;5953- 59PubMedGoogle ScholarCrossref
27.
Kessler  RCRubinow  DRHolmes  CAbelson  JMZhao  S The epidemiology of DSM-III-R bipolar I disorder in a general population survey.  Psychol Med 1997;271079- 1089PubMedGoogle ScholarCrossref
28.
Bebbington  PNayani  T The psychosis screening questionnaire.  Int J Methods Psychiatr Res 1995;511- 19Google Scholar
29.
Aromaa  AedKoskinen  Sed Health and functional capacity in Finland: baseline results of the Health 2000 Health Examination Survey.  Helsinki, Finland National Public Health Institute 2004; Publication B12/2004http://www.ktl.fi/terveys2000/index.uk.htmlAugust 8, 2005
30.
Wittchen  H-UPfister  H DIA-X-Interviews: Manual für screening-verfahren und Interview; Interviewheft Längsschnittuntersuchung (DIA-X-Lifetime); Ergänzungsheft (DIAX-Lifetime); Interviewheft Querschnittuntersuchung (DIA-X-12 Monate); Ergänzungsheft (DIA-X-12 Monate); PC-Programm zur Durchführung des Interviews (Längs- und Querschnittuntersuchung).  Frankfurt, Germany Swets and Zeitlinger 1997; Auswertungsprogramm
31.
Pirkola  SPIsometsä  ESuvisaari  JAro  HJoukamaa  MPoikolainen  KKoskinen  SAromaa  ALönnqvist  JK DSM-IV mood-, anxiety- and alcohol use disorders and their comorbidity in the Finnish general population: results from the Health 2000 Study.  Soc Psychiatry Psychiatr Epidemiol 2005;401- 10PubMedGoogle ScholarCrossref
32.
First  MBAnthony  JCTepper  SDryman  A Structured Clinical Interview for DSM-IV Axis I Disorders, Research Version, Nonpatient Edition (SCID-I/NP).  New York Biometrics Research, New York State Psychiatric Institute1997;
33.
Kuoppasalmi  KLönnqvist  JPylkkänen  KHuttunen  M Classification of mental disorders in Finland: a comparison of the Finnish classification of mental disorders in 1987 with DSM-III-R.  Psychiatr Fenn 1989;2065- 81Google Scholar
34.
American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision.  Washington, DC American Psychiatric Association 2000;
35.
SAS Institute Inc, SAS Version 8.02.  Cary, NC SAS Institute Inc 1999;
36.
Research Triangle Institute, SUDAAN Language Manual, Release 9.0.0.  Research Triangle Park, NC Research Triangle Institute 2004;
37.
Jacobi  FWittchen  HUHolting  CHofler  MPfister  HMuller  NLieb  R Prevalence, co-morbidity and correlates of mental disorders in the general population: results from the German Health Interview and Examination Survey (GHS).  Psychol Med 2004;34597- 611PubMedGoogle ScholarCrossref
38.
Wittchen  HUEssau  CAvon Zerssen  DKrieg  JCZaudig  M Lifetime and six-month prevalence of mental disorders in the Munich Follow-Up Study.  Eur Arch Psychiatry Clin Neurosci 1992;241247- 258PubMedGoogle ScholarCrossref
39.
Canino  GJBird  HRShrout  PERubio-Stipec  MBravo  MMartinez  RSesman  MGuevara  LM The prevalence of specific psychiatric disorders in Puerto Rico.  Arch Gen Psychiatry 1987;44727- 735PubMedGoogle ScholarCrossref
40.
McGorry  PDSingh  BSConnell  SMcKenzie  DVan Riel  RJCopolov  DL Diagnostic concordance in functional psychosis revisited: a study of inter-relationships between alternative concepts of psychotic disorder.  Psychol Med 1992;22367- 378PubMedGoogle ScholarCrossref
41.
Lehtinen  VJoukamaa  MJyrkinen  TLahtela  KRaitasalo  RMaatela  JAromaa  A Mental Health and Mental Disorders in the Finnish Adult Population.  Turku and Helsinki, Finland Social Insurance Institution 1991;
42.
Isohanni  MJones  PBMoilanen  KRantakallio  PVeijola  JOja  HKoiranen  MJokelainen  JCroudace  TJärvelin  M Early developmental milestones in adult schizophrenia and other psychoses: a 31-year follow-up of the Northern Finland 1966 Birth Cohort.  Schizophr Res 2001;521- 19PubMedGoogle ScholarCrossref
43.
Hovatta  ITerwilliger  JDLichtermann  DMäkikyrö  TSuvisaari  JPeltonen  LLönnqvist  J Schizophrenia in the genetic isolate of Finland.  Am J Med Genet 1997;74353- 360PubMedGoogle ScholarCrossref
44.
McGrath  JSaha  SWelham  JEl Saadi  OMacCauley  CChant  D A systematic review of the incidence of schizophrenia: the distribution of rates and the influence of sex, urbanicity, migrant status and methodology.  BMC Med 2004;213PubMedGoogle ScholarCrossref
45.
Aleman  AKahn  RSSelten  JP Sex differences in the risk of schizophrenia: evidence from meta-analysis.  Arch Gen Psychiatry 2003;60565- 571PubMedGoogle ScholarCrossref
46.
Joukamaa  MHeliövaara  MKnekt  PAromaa  ARaitasalo  RLehtinen  V Mental disorders and cause-specific mortality.  Br J Psychiatry 2001;179498- 502PubMedGoogle ScholarCrossref
47.
Heilä  HHaukka  JSuvisaari  JLönnqvist  J Mortality among patients with schizophrenia and reduced psychiatric hospital care.  Psychol Med 2005;35725- 732PubMedGoogle ScholarCrossref
48.
Salokangas  RK First-contact rate for schizophrenia in community psychiatric care: consideration of the oestrogen hypothesis.  Eur Arch Psychiatry Clin Neurosci 1993;242337- 346PubMedGoogle ScholarCrossref
49.
Coryell  WLavori  PEndicott  JKeller  MVanEerdewegh  M Outcome in schizoaffective, psychotic, and nonpsychotic depression: course during a six- to 24-month follow-up.  Arch Gen Psychiatry 1984;41787- 791PubMedGoogle ScholarCrossref
50.
Kendler  KS Demography of paranoid psychosis (delusional disorder): a review and comparison with schizophrenia and affective illness.  Arch Gen Psychiatry 1982;39890- 902PubMedGoogle ScholarCrossref
51.
Copeland  JRDewey  MEScott  AGilmore  CLarkin  BACleave  NMcCracken  CFMcKibbin  PE Schizophrenia and delusional disorder in older age: community prevalence, incidence, comorbidity, and outcome.  Schizophr Bull 1998;24153- 161PubMedGoogle ScholarCrossref
52.
Tsuang  MTLevitt  JJSimpson  JC Schizoaffective disorder. Hirsch   SRWeinberger  DReds Schizophrenia. 2nd Oxford, England Blackwell Science Ltd 2003;46- 57Google Scholar
53.
Scully  PJOwens  JMKinsella  AWaddington  JL Schizophrenia, schizoaffective and bipolar disorder within an epidemiologically complete, homogeneous population in rural Ireland: small area variation in rate.  Schizophr Res 2004;67143- 155PubMedGoogle ScholarCrossref
54.
Singh  SPBurns  TAmin  SJones  PBHarrison  G Acute and transient psychotic disorders: precursors, epidemiology, course and outcome.  Br J Psychiatry 2004;185452- 459PubMedGoogle ScholarCrossref
55.
Pini  Sde Queiroz  VPagnin  DPezawas  LAngst  JCassano  GBWittchen  HU Prevalence and burden of bipolar disorders in European countries.  Eur Neuropsychopharmacol 2005;15425- 434PubMedGoogle ScholarCrossref
56.
Taiminen  TRanta  KKarlsson  HLauerma  HLeinonen  KMWallenius  EKaljonen  ASalokangas  RKR Comparison of clinical and best-estimate research DSM-IV diagnoses in a Finnish sample of first-admission psychosis and severe affective disorder.  Nord J Psychiatry 2001;55107- 111PubMedGoogle ScholarCrossref
57.
Mantere  OSuominen  KLeppamäki  SValtonen  HArvilommi  PIsometsä  E The clinical characteristics of DSM-IV bipolar I and II disorders: baseline findings from the Jorvi Bipolar Study (JoBS).  Bipolar Disord 2004;6395- 405PubMedGoogle ScholarCrossref
58.
Väisänen  E Psychiatric Disorders in Finland: A Comparative Study With Special Reference to Geographical and Social Factors [in Finnish, with English summary].  Helsinki, Finland Publications of the Social Insurance Institution 1975;
59.
Veijola  JRäsänen  PIsohanni  MTiihonen  J Low incidence of mania in northern Finland.  Br J Psychiatry 1996;168520- 521PubMedGoogle ScholarCrossref
60.
Räsänen  PTiihonen  JHakko  H The incidence and onset-age of hospitalized bipolar affective disorder in Finland.  J Affect Disord 1998;4863- 68PubMedGoogle ScholarCrossref
61.
Kieseppä  TPartonen  THaukka  JKaprio  JLönnqvist  J High concordance of bipolar I disorder in a nationwide sample of twins.  Am J Psychiatry 2004;1611814- 1821PubMedGoogle ScholarCrossref
62.
Johnson  JHorwarth  EWeissman  MM The validity of major depression with psychotic features based on a community study.  Arch Gen Psychiatry 1991;481075- 1081PubMedGoogle ScholarCrossref
63.
Ohayon  MMSchatzberg  AF Prevalence of depressive episodes with psychotic features in the general population.  Am J Psychiatry 2002;1591855- 1861PubMedGoogle ScholarCrossref
64.
Cantwell  RBrewin  JGlazebrook  CDalkin  TFox  RMedley  IHarrison  G Prevalence of substance misuse in first-episode psychosis.  Br J Psychiatry 1999;174150- 153PubMedGoogle ScholarCrossref
65.
Virtanen  ASalaspuro  MPartanen  AKaukonen  OKinnunen  A 2004 National report to the EMCDDA by the Finnish National Focal point. Drugs in Finland Web site.http://www.stakes.fi/verkkojulk/January 24, 2005
66.
Ritchie  KArtero  SBeluche  IAncelin  MLMann  ADupuy  AMMalafosse  ABoulenger  JP Prevalence of DSM-IV psychiatric disorder in the French elderly population.  Br J Psychiatry 2004;184147- 152PubMedGoogle ScholarCrossref
67.
Isohanni  MMäkikyrö  TMoring  JRäsänen  PHakko  HPartanen  UKoiranen  MJones  P A comparison of clinical and research DSM-III-R diagnoses of schizophrenia in a Finnish national birth cohort: clinical and research diagnoses of schizophrenia.  Soc Psychiatry Psychiatr Epidemiol 1997;32303- 308PubMedGoogle ScholarCrossref
68.
Jablensky  AMcGrath  JHerrman  HCastle  DGureje  OEvans  MCarr  VMorgan  VKorten  AHarvey  C Psychotic disorders in urban areas: an overview of the Study on Low Prevalence Disorders.  Aust N Z J Psychiatry 2000;34221- 236PubMedGoogle ScholarCrossref
69.
Kendler  KSMcGuire  MGruenberg  AMO’Hare  ASpellman  MWalsh  D The Roscommon Family Study, I: methods, diagnosis of probands, and risk of schizophrenia in relatives.  Arch Gen Psychiatry 1993;50527- 540PubMedGoogle ScholarCrossref
70.
King  MCoker  ELeavey  GHoare  AJohnson-Sabine  E Incidence of psychotic illness in London: comparison of ethnic groups.  BMJ 1994;3091115- 1119PubMedGoogle ScholarCrossref
71.
McNaught  ASJeffreys  SEHarvey  CAQuayle  ASKing  MBBird  AS The Hampstead Schizophrenia Survey 1991, II: incidence and migration in inner London.  Br J Psychiatry 1997;170307- 311PubMedGoogle ScholarCrossref
72.
Arajärvi  RSuvisaari  JSuokas  JSchreck  MHaukka  JHintikka  JPartonen  TLönnqvist  J Prevalence and diagnosis of schizophrenia based on register, case record and interview data in an isolated Finnish birth cohort born 1940-1969.  Soc Psychiatry Psychiatr Epidemiol 2005;40808- 816PubMedGoogle ScholarCrossref
73.
Suvisaari  JMHaukka  JKTanskanen  AJLönnqvist  JK Decline in the incidence of schizophrenia in Finnish cohorts born from 1954 to 1965.  Arch Gen Psychiatry 1999;56733- 740PubMedGoogle ScholarCrossref
74.
Kennedy  NEveritt  BBoydell  JVan Os  JJones  PBMurray  RM Incidence and distribution of first-episode mania by age: results from a 35-year study.  Psychol Med 2005;35855- 863PubMedGoogle ScholarCrossref
×