Author Affiliations: Social, Genetic and Developmental Psychiatry Centre (Drs Rutter, Caspi, Maughan, and Moffitt) and Department of Child and Adolescent Psychiatry (Dr Goodman), Institute of Psychiatry, King's College, London, England; Christchurch School of Medicine, Christchurch, New Zealand (Dr Fergusson and Mr Horwood); Office for National Statistics, London, England (Dr Meltzer); and University of Warwick, Coventry, England (Dr Carroll).
Context An influential article published in 1990 claimed that the increased
rate of reading disability in boys was a consequence of referral bias.
Objectives To summarize the history of research on sex differences in reading disability
and to provide new evidence from 4 independent epidemiological studies about
the nature, extent, and significance of sex differences in reading disability.
Design, Setting, and Participants The Dunedin Multidisciplinary Health and Development Study comprised
989 individuals (52.1% male) in a cohort born between April 1972 and March
1973 in Dunedin, New Zealand, and followed up from age 3 years; reading performance
and IQ were assessed at ages 7, 9, and 11 years using the Burt Word Reading
Test and the Wechsler Intelligence Scale for Children–Revised (WISC-R),
respectively. The Christchurch Health and Development Study comprised 895
individuals (50% male) in a prospectively studied cohort born in the Christchurch,
New Zealand, region during a 4-month period in 1977; reading performance and
IQ were assessed at ages 8 to 10 years using the Burt Word Reading Test and
the WISC-R. The Office for National Statistics (ONS) Study comprised a UK
nationally representative sample of 5752 children (50.1% male) aged 9 to 15
years in 1999; reading was assessed on the British Ability Scales II and IQ
on the British Picture Vocabulary Scales II. The Environmental Risk Longitudinal
Twin Study (E-Risk) comprised 2163 twin children from England and Wales (49.1%
male) identified at birth in 1994 and 1995 and included administration of
the Test of Word Reading Efficiency at age 7 years and the Wechsler Preschool
and Primary Scale of Intelligence–Revised as a test of IQ at age 5 years.
Main Outcome Measure Reading performance by sex in the lowest 15% of the distribution for
all 4 studies, with and without taking IQ into account.
Results In all 4 studies, the rates of reading disability were significantly
higher in boys. For non–IQ-referenced reading disability: Dunedin study,
21.6% in boys vs 7.9% in girls (odds ratio [OR], 3.19; 95% confidence interval
[CI], 2.15-4.17); Christchurch study, 20.6% in boys vs 9.8% in girls (OR,
2.38; 95% CI, 1.62-3.50); ONS study, 17.6% in boys vs 13.0% in girls (OR,
1.43; 95% CI, 1.23-1.65); and E-Risk, 18.0% in boys vs 13.0% in girls (OR,
1.39; 95% CI, 1.04-1.86). The rates for IQ-referenced reading disabilities
Conclusion Reading disabilities are clearly more frequent in boys than in girls.
Rutter M, Caspi A, Fergusson D, Horwood LJ, Goodman R, Maughan B, Moffitt TE, Meltzer H, Carroll J. Sex Differences in Developmental Reading DisabilityNew Findings From 4 Epidemiological Studies. JAMA. 2004;291(16):2007-2012. doi:10.1001/jama.291.16.2007