Incidence of reading disability in a population-based birth cohort, 1976-1982, Rochester, Minn

Objective: To report the incidence of reading disability among school-aged children. Subjects and Methods: In this population-based, retrospective birth cohort study, subjects included all 5718 children born between 1976 and 1982 who r emained in Rochester, Minn, after the age of 5 years. Based on records from all public and nonpublic schools, medical facilities, and private tutorial services and on results of all individually administered IQ and achievemen t tests, extensive medical, educational, and socioeconomic information were abstracted. Reading disability was established with use of research criter ia based on 4 formulas (2 regression-based discrepancy, 1 non-regression-ba sed discrepancy, and 1 low achievement). Results: Cumulative incidence rates of reading disability varied from 5.3% to 11.8% depending on the formula used. Boys were 2 to 3 times more likely to be affected than girls, regardless of the identification methods applied . Conclusions: In this population-based birth cohort, reading disability was common among school-aged children and significantly more frequent among boy s than girls, regardless of definition.