Context Few depressed older adults receive effective treatment in primary care
settings.
Objective To determine the effectiveness of the Improving Mood–Promoting
Access to Collaborative Treatment (IMPACT) collaborative care management program
for late-life depression.
Design Randomized controlled trial with recruitment from July 1999 to August
2001.
Setting Eighteen primary care clinics from 8 health care organizations in 5
states.
Participants A total of 1801 patients aged 60 years or older with major depression
(17%), dysthymic disorder (30%), or both (53%).
Intervention Patients were randomly assigned to the IMPACT intervention (n = 906)
or to usual care (n = 895). Intervention patients had access for up to 12
months to a depression care manager who was supervised by a psychiatrist and
a primary care expert and who offered education, care management, and support
of antidepressant management by the patient's primary care physician or a
brief psychotherapy for depresssion, Problem Solving Treatment in Primary
Care.
Main Outcome Measures Assessments at baseline and at 3, 6, and 12 months for depression, depression
treatments, satisfaction with care, functional impairment, and quality of
life.
Results At 12 months, 45% of intervention patients had a 50% or greater reduction
in depressive symptoms from baseline compared with 19% of usual care participants
(odds ratio [OR], 3.45; 95% confidence interval [CI], 2.71-4.38; P<.001). Intervention patients also experienced greater rates of
depression treatment (OR, 2.98; 95% CI, 2.34-3.79; P<.001),
more satisfaction with depression care (OR, 3.38; 95% CI, 2.66-4.30; P<.001), lower depression severity (range, 0-4; between-group
difference, −0.4; 95% CI, −0.46 to −0.33; P<.001), less functional impairment (range, 0-10; between-group
difference, −0.91; 95% CI, −1.19 to −0.64; P<.001), and greater quality of life (range, 0-10; between-group
difference, 0.56; 95% CI, 0.32-0.79; P<.001) than
participants assigned to the usual care group.
Conclusion The IMPACT collaborative care model appears to be feasible and significantly
more effective than usual care for depression in a wide range of primary care
practices.
Major depression and dysthymic disorder affect between 5% and 10% of
older adults seen in the primary care setting.1-3 Late-life
depression is often chronic or recurrent4-8 and
is associated with substantial suffering, functional impairment, and diminished
health-related quality of life.9 Depressed,
older primary care patients are frequent users of general medical services5,10-12 and
may have poor adherence to medical treatments.13 They
are also at increased risk of death from suicide14 and
medical illnesses.15-17 Although
late-life depression can be successfully treated with antidepressant medications
or psychotherapy,18-21 few
depressed older adults receive adequate trials of such treatments in primary
care22-28 or
see a mental health specialist.25,29-35 Efforts
to improve late-life depression treatment using screening and health care
practitioner feedback and education have not resulted in consistent improvements
in depression.22,23 A more comprehensive
intervention strategy may be needed to improve outcomes for this population.
We enrolled 1801 depressed, older adults from 18 primary care clinics
across the United States in a randomized trial of a primary care–based
collaborative care model for late-life depression, the Improving Mood–Promoting
Access to Collaborative Treatment (IMPACT) program,36 compared
with care as usual. The IMPACT intervention includes key components of evidence-based
models for chronic illness care37,38:
collaboration among primary care practitioners, patients, and specialists
on a common definition of the problem, development of a therapeutic alliance,
a personalized treatment plan that includes patient preferences, proactive
follow-up and outcomes monitoring by a depression care manager, targeted use
of specialty consultation, and protocols for stepped care. Intervention patients
had access to an IMPACT care manager for up to 12 months. Usual care patients
could use any primary care or specialty mental health care services available
to them in usual care. After 12 months, all study participants continued with
their regular primary care practitioners as usual.
This article examines health outcomes throughout 12 months. We hypothesized
that patients assigned to the IMPACT intervention would have higher rates
of depression treatment, greater satisfaction with depression care, greater
improvements in depression, less health-related functional impairment, and
higher quality of life than usual care patients.
The IMPACT study is a multisite randomized controlled trial of a collaborative
intervention program for late-life depression in primary care.36,39-41 Study
protocols were developed in collaboration with all participating organizations,
reviewed by a study advisory board, and approved by the institutional review
boards at all sites and the study coordinating center. All participants gave
written informed consent.
Seven study sites representing 8 diverse health care organizations with
a total of 18 primary care clinics in 5 states participated in the study (Table 1). We estimated that 650 participants
each were required in the intervention and control groups to have a 95% chance
of detecting as significant (at the 2-sided .05 level) a difference of 0.10
(SD, 0.50) in the mean score of the 20 depression items from the Symptom Checklist–90
(SCL-20)42 depression scores. To compensate
for patient attrition, we planned to enroll 875 patients per group. To identify
a sample of depressed, older adults who could participate in a quality improvement
intervention such as IMPACT under real-world practice conditions, each site
used a 2-pronged strategy to recruit study participants from July 1999 to
August 2001 (Figure 1).36
The first strategy relied on referrals of depressed older adults from
primary care practitioners, other clinic staff, or patients themselves in
response to clinic promotions of the program. The second method consisted
of systematic depression screening of English-speaking, older adults who used
the participating primary care clinics with a 2-item depression screener adapted
from the PRIME-MD study. These screens were administered either in person
or by telephone.43 Of the 32 908 patients
approached for screening, 5246 (16%) either refused to be screened or participated
in the initial screening but refused further interviews. A total of 1791 (5%)
of the initial screens were incomplete, and 23 233 (71%) of those screened
were not eligible because they did not endorse one of the core depression
symptoms (95% of those ineligible) or because of logistic reasons, such as
lack of transportation or access to a telephone (5% of those ineligible).
Of the 2190 patients referred to the study, 308 (14%) refused the initial
eligibility screen or further interviews. Fifty-four (3%) had incomplete initial
screens, and 202 (9%) were ineligible because they were younger than 60 years
or they did not plan to use the participating clinic during the coming 12
months.
The remaining 2638 (8%) of those screened and 1626 (74%) of those referred
underwent a 30- to 60-minute structured, computer-assisted interview by trained
lay interviewers to determine study eligibility.36 This
interview included the structured clinical interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (SCID)
to assess whether patients met research diagnostic criteria for major depression
or dysthymia.44,45 Inclusion criteria
were age 60 years or older, plans to use one of the participating clinics
as the main source of general medical care in the coming year, and a diagnosis
of current major depression or dysthymic disorder according to the SCID. Approximately
2% (n = 99) of otherwise eligible patients were excluded because of current
drinking problems (a score of ≥2 on the CAGE questionnaire)46;
3% (n = 145) were excluded because of a history of bipolar disorder or psychosis36; 2% (n = 85) were excluded because they were in ongoing
treatment with a psychiatrist; and approximately 1% (n = 44) were excluded
because they met screening criteria for severe cognitive impairment defined
by a score of less than 3 on a 6-item cognitive screen.47 Less
than 1% were excluded because they were found to be at acute risk for suicide
and needed immediate care. Our 2-pronged recruitment method identified 2102
eligible older adults with major depression or dysthymic disorder (approximately
2% of all older adults served at the participating clinics); 1801 (86% of
those eligible) enrolled in the study and completed a structured baseline
interview.36
After the baseline interview, participants were randomly assigned to
the IMPACT intervention or usual care. The random assignment was stratified
by recruitment method (screening or referral) and clinic. Within each stratum,
participants were assigned according to a random number sequence that was
developed using a computer random number generator at the coordinating center.
Random assignment information was contained in a set of numbered, sealed envelopes
for each stratum that were used sequentially for newly enrolled patients at
each clinic.36
The IMPACT intervention has been described in detail elsewhere.36,39,40,48 Intervention
participants received a 20-minute educational videotape and a booklet about
late-life depression49,50 and
were encouraged to have an initial visit with a depression care manager at
the primary care clinic. Care managers were nurses or psychologists who were
trained for the study as a depression clinical specialist (DCS).36,39,40 During
the initial visit, the DCS conducted a clinical and psychosocial history,
reviewed the educational materials, and discussed patient preferences for
depression treatment (antidepressant medications or psychotherapy). New cases
and cases needing treatment plan adjustments were discussed with a supervising
team psychiatrist and a liaison primary care physician during a weekly team
meeting. The DCS then worked with the patient and his/her regular primary
care practitioner to establish a treatment plan according to a recommended
treatment algorithm, but patients and their primary care practitioners made
the actual treatment choices.36 The IMPACT
treatment algorithm suggested an initial choice of an antidepressant medication
(usually a selective serotonin reuptake inhibitor) or a course of Problem
Solving Treatment in Primary Care (PST-PC), a 6- to 8-session, brief, structured
psychotherapy for depression,51-55 delivered
by the DCS in the primary care setting. For patients who were already taking
antidepressant medications but who were still depressed, the recommendation
was to increase the dose or to augment the antidepressant with a trial of
PST-PC (for partial responders) or to switch to a different medication or
PST-PC (for nonresponders). Patients' regular primary care practitioners were
asked to write all antidepressant prescriptions. The DCSs also encouraged
patients to schedule pleasant life events and referred them to additional
health or social services as clinically indicated.
As care managers, DCSs attempted to follow up patients for up to 12
months, monitoring treatment response with the Patient Health Questionnaire
956 and a Web-based clinical information system.57 During the acute treatment phase, in-person or telephone
follow-up contacts were suggested at least every other week. Patients who
achieved recovery from depression (≥50% reduction in the Patient Health
Questionnaire 9 score and fewer than 3 of 9 symptoms of major depression)
were engaged in developing a relapse prevention plan and then followed up
monthly by the DCS. Patients who did not respond to initial treatment were
discussed with the IMPACT team and a "step 2" treatment plan was developed
that could include augmentation of an antidepressant medication, a switch
to a different antidepressant, a switch from medications to PST-PC, or vice
versa. Team psychiatrists were encouraged to see patients who presented diagnostic
challenges or who had persistent depression for in-person consultations in
the primary care setting. Patients who did not respond after 10 weeks of step
2 treatment were again reviewed by the team, and additional treatments, such
as further medication changes, psychotherapy, hospitalization, or electroconvulsive
therapy, were considered.
We used baseline and 3-, 6-, and 12-month follow-up data from all 1801
study participants. Baseline interviews were conducted by trained lay interviewers
using structured computerized interviews36 before
randomization; thus, the interviewers were blind to study assignment. Blind
follow-up interviews were performed at 3, 6, and 12 months by trained interviewers
at a telephone survey research group using computer-assisted telephone interviews,36 with survey response rates of 90% at 3 months, 87%
at 6 months, and 83% at 12 months (Figure
1).
Baseline interviews assessed sociodemographic characteristics, the severity
of depressive symptoms using the SCL-20,42 SCID
diagnoses of major depression or dysthymia,44,45 and
health-related functional impairment using an index developed from the Sheehan
disability scale that incorporates impairments in work, family, and other
social functioning.58,59 Respondents
rated their overall quality of life in the past month (including physical
and mental well-being) on a scale from 0 (about as bad as dying) to 10 (life
is perfect) and indicated whether they had been diagnosed as having or had
been treated for any of 10 common chronic medical problems in the past 3 years.
The Cornell Services Index60 and additional
questions about the use of antidepressant medications, counseling, or psychotherapy
assessed health services use in the past 3 months.61 Earlier
research at one of our study sites found high rates of agreement between self-reported
antidepressant use and prescription fill data from a pharmacy database.62,63
Dependent variables in our analyses included self-reported use of antidepressants
or psychotherapy, satisfaction with depression care (percentage who answered
"excellent" or "very good"), mean SCL-20 depression scores, treatment response
(≥50% decrease in SCL-20 score from baseline), complete remission of depression
symptoms (SCL-20 score <0.5), major depression as assessed by the SCID,
health-related functional impairment, and quality of life. We estimated the
costs of providing IMPACT intervention services based on detailed study records
of all patient contacts, mean salary and benefit costs of DCSs plus 30% overhead
costs, and the cost of supervision and consultation from team psychiatrists
and primary care experts.
We conducted bivariate analyses to compare demographic and clinical
characteristics of intervention and usual care patients at baseline (Table 2). For each dependent variable,
we conducted an intention-to-treat analysis of repeated measures. We fitted
mixed-effects regression models for continuous variables or mixed-effects
logistic regression models for dichotomous variables using baseline and 3-,
6-, and 12-month follow-up data with regression adjustment for recruitment
method (screening or referral) and participating study organizations. In the
mixed-effects models, we treated time as a categorical variable and examined
the fixed effects for time, intervention condition, and their interactions.
We specified the covariance structure within patients using an unstructured
model to account for the within-patient correlation over time.64 For
predicting depression severity and major depression at follow-up, we performed
additional analyses that tested the interaction of intervention status with
recruitment method (referral or screening), participating organizations, and
depression diagnosis (major depression or dysthymia). Because of multiple
comparisons, we used a conservative P value of less
than .01 to detect statistically significant differences. All analyses were
conducted using SAS software, version 8 (SAS Institute Inc, Cary, NC).
We used an extended hot deck multiple imputation technique that modifies
the predictive mean matching method65,66 to
impute item-level missing data.67 Rates of
item-level missing data were less than 2% for all variables discussed in this
article. The results across 5 imputed data sets were combined by averaging,
and SEs were adjusted to reflect both within-imputation variability and between-imputation
variability.67 Although there were no significant
differences in the completion rate of follow-up interviews between the intervention
and usual care groups, we found somewhat different predictors of follow-up
response in intervention and usual care patients. We used an approximate Bayesian
bootstrap multiple imputation method68 to impute
unit-level missing data and adjust for these differences. Imputations were
conducted separately in the intervention and usual care groups.
The enrolled sample was clinically and sociodemographically diverse
(Table 2). The mean age of participants
was 71.2 years (SD, 7.5 years), and 65% were women. With 23% of participants
from ethnic minority groups (12% African Americans, 8% Latinos, and 3% other
ethnic minorities), we had a somewhat greater representation of ethnic minorities
than a national sample of older adults.69 Most
participants (53%) met diagnostic criteria for major depression and dysthymic
disorder, and 71% reported 2 or more prior depressive episodes. The mean SCL-20
depression score42 was 1.7 (SD, 0.6), indicating
moderate to severe depression. Six percent of participants reported thoughts
of suicide in the past month. One third (35%) showed some evidence of cognitive
impairment, and 29% screened positive for panic disorder or posttraumatic
stress disorder. Participants reported a mean of 3.2 (SD, 1.7) of 10 common
comorbid medical conditions. About half (46%) reported depression treatment
(antidepressant medication or psychotherapy) in the past 3 months.63 We found no significant differences in sociodemographic
and clinical characteristics between the intervention and control groups.
Intervention Implementation
Most (98%) of the 906 intervention participants completed an initial
visit with a DCS. Intervention participants had a mean of 9.15 (SD, 6.17)
in-person visits and 6.10 (SD, 5.13) telephone contacts with a DCS, and 11%
were seen for a consultation by a team psychiatrist. The majority (80%) had
at least 1 trial of an antidepressant, and approximately one third (30%) received
PST-PC. The mean number of PST-PC sessions was 6.34 (SD, 4.26).
Intervention patients were significantly more likely to use antidepressants
or psychotherapy than usual care participants at all follow-ups (Table 3). Intervention patients reported
antidepressant use for 6.6 months (SD, 4.9 months) of the 12-month study period
compared with 4.6 months (SD, 5.0 months) in the usual care group (t = 8.12, P<.001). They also reported greater
satisfaction with depression care at 3 and 12 months (satisfaction was not
assessed at 6 months). Four patients in the usual care group and 5 intervention
patients reported psychiatric hospitalizations during the 12-month study period.
Intervention patients had significantly lower depression severity (measured
by SCL-20 depression scores) during all follow-up points, with the difference
between intervention and usual care increasing from the 3- to the 12-month
follow-up (Figure 2). Intervention
patients also had significantly higher rates of treatment response (at least
50% reduction in the SCL-20 score from baseline) and of complete remission
of depressive symptoms (SCL-20 score of <0.5)70 than
usual care participants (Table 4).
We are not aware of any attempted or completed suicides in either group.
We observed significant main effects of participating organizations
on depression. For example, the proportion of patients who met criteria for
major depression across the participating sites ranged from 57% to 84% at
baseline and from 18% to 36% at 6 months. We did not find any significant
interaction effects of intervention status with organization (F = 1.61; P = .13), intervention with recruitment method (t = 1.17; P = .24), or intervention with baseline
depression diagnosis (major depression or dysthymia, t =
−1.12; P = .26). Across all sites, intervention
patients had a significantly greater reduction in rates of major depression
(from a mean of 71% at baseline to 22% at 6 months) than usual care participants
(from 68% to 35%; the SCID to assess major depression was not administered
at 3 or 12 months).
Intervention patients also reported less health-related functional impairment
(P<.001 at 3 and 12 months, P = .02 at 6 months) and greater overall quality of life in the past
month (P<.001 at all follow-ups) than usual care
participants (Table 4). We conducted
sensitivity analyses using design-based permutation tests. For each outcome
variable, we used the imputation version least favorable to the intervention.
These conservative analyses gave similar results and are not presented in
this article.
We estimate the mean costs of providing IMPACT services to be $553 per
intervention patient for a 12-month period. These costs include $7 for the
educational brochure and videotape, $418 for DCS services, $70 for supervision
and in-person consultations with team psychiatrists, and $58 for supervision
of DCSs by primary care experts. All visits with DCSs and team psychiatrists
were provided free of charge to the patients. Patients and their insurers
were responsible for all other health care costs, including antidepressant
medications. Information on these costs will be reported in a subsequent article.
Recent studies69,71-73 have
reported significant increases in rates of antidepressant use during the past
10 years. Almost half of our patients reported depression treatment during
the 3 months before the study and more than half of our usual care patients
reported antidepressant use or psychotherapy during the 12-month study period.
Our findings suggest that despite this recent increase in antidepressant use,
treatment of late-life depression in primary care remains challenging. At
the 12-month follow-up, only 19% of usual care patients reported at least
a 50% reduction in depressive symptoms from baseline and only 8% were completely
free of depression symptoms.
Compared with these relatively modest effects of usual care treatment,
intervention patients had significantly higher rates of depression treatment,
greater satisfaction with depression care, and greater improvements in depression.
Our findings are similar to earlier studies of collaborative care for mixed-aged
adults with depression that integrated psychiatrists or psychologists into
primary care settings and found greater improvements in depression in intervention
than usual care patients.74,75 Our
treatment effects in terms of number needed to treat to achieve a treatment
response at 12 months (number needed to treat, 4; 95% confidence interval,
3-5) are similar to a number needed to treat of 4 reported in a Cochrane review
of antidepressants compared with placebo or no treatment in medically ill
adults.76 Subjects assigned to the IMPACT intervention
also reported less health-related impairment in work, family, and social functioning
and better quality of life than usual care patients, suggesting that the effects
of this intervention on health extend beyond reducing depressive symptoms.
We are particularly encouraged by the observation that differences between
intervention and control patients in all health outcomes examined increased
during the 12-month follow-up period. Longer-term follow-up will be needed
to determine if these differences persist after discontinuation of the intervention
resources at 12 months.
Our sample was recruited from 8 diverse health care organizations nationally,
representing a wide variety of practices and patients.36 For
example, the median household income of participants from the 8 organizations
varied 5-fold ($8400 to $40 000 per year), and the proportion of patients
with a high school education varied 3-fold (32% to 93%). We observed substantial
intervention effects on depression at each of the 8 health care organizations,
indicating that the IMPACT care model is feasible and effective in a range
of primary care clinics that serve patients with widely diverse sociodemographic
and clinical characteristics. We did not find significant interactions between
intervention status and baseline depression diagnosis (major depression or
dysthymic disorder) or between intervention status and recruitment method
(screening or referral). We believe that our screening procedures identified
a number of depressed older adults who might not have been recognized by their
primary care practitioners and agree with the recent recommendation by the
US Preventive Services Task Force that screening for depression in primary
care is effective when coupled with systematic depression treatments such
as those offered in our study.77
Despite substantial improvements in depression and quality of life,
only approximately half of the intervention patients experienced a 50% reduction
in depressive symptoms and only 25% to 30% became completely free of depressive
symptoms. This may be due to greater medical comorbidity (a mean of 3.2 chronic
medical illnesses and 65% with chronic pain), greater ambivalence about depression
treatment among patients and practitioners, and lower treatment intensity
in this effectiveness study conducted under naturalistic practice conditions
compared with treatment efficacy studies with select samples in academic medical
centers.36 It is also questionable whether
complete freedom from symptoms, such as fatigue or lack of energy, is a realistic
goal in older adults with multiple chronic medical illnesses. Further research
is needed to examine the long-term outcomes of persistently depressed patients,
to identify factors associated with treatment participation, adherence, and
treatment resistance, and to develop effective interventions for this group.
Possible strategies might include earlier and more aggressive use of in-person
psychiatric consultation for nonresponders to antidepressants or psychotherapy
in primary care or more aggressive use of additional treatments such as electroconvulsive
therapy.
Most participants (51%) stated a preference for psychotherapy during
the baseline interview before randomization, and 30% of intervention patients
received a course of PST-PC in primary care. Given that only 8% of patients
reported receiving counseling or psychotherapy in the 3 months before the
baseline interview, it appears that the intervention program substantially
increased the likelihood that patients received psychotherapy by offering
this service in the primary care setting. However, when confronted with the
need to travel to the clinic for PST-PC sessions, some patients may have opted
to try antidepressants instead of PST-PC.
Our estimated 12-month intervention cost of $553 is consistent with
cost estimates from an earlier study of collaborative care for depression
using nurse care managers.78 It seems relatively
modest given total annual Medicare spending of $5506 per enrollee in 199812,79 and the fact that health care costs
for depressed, older adults are up to 50% higher than for older adults without
depression.5,12 We plan to examine
differences in total health care costs using administrative data from the
participating organizations to compare the cost-effectiveness of the intervention
to usual care.
Our study design may have biased our comparisons in favor of the usual
care group.36 Referring practitioners were
notified if a patient meeting study criteria was assigned to usual care, possibly
resulting in treatment that would not have occurred in true usual care. Practitioners
treated both intervention and usual care patients from 1999 to 2002; a spillover
effect in which primary care practitioners applied improved skills learned
from exposure to the intervention to the treatment of their usual care patients
may have resulted. However, earlier studies23,80 have
not found substantial effects of notification about depression status or physician
training on usual care. Finally, we used a protocol to identify patients with
thoughts of suicide during the follow-up interviews and referred them to appropriate
clinical evaluation regardless of group assignment, possibly resulting in
additional mental health care for the most depressed usual care participants.
These biases may contribute to an underestimation of the effectiveness of
the intervention compared with usual care outside a research setting. Additional
limitations include our reliance on self-reports of chronic medical conditions
and antidepressant and psychotherapy use. However, earlier research at 2 of
our study sites61,62,81 found
high rates of agreement between self-reported antidepressant use and prescription
fill data from a pharmacy database.
The IMPACT model, a collaborative, stepped care management intervention
for late-life depression, appears to be feasible and significantly more effective
than usual care in a wide range of primary care practices.
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