MILD MENTAL-RETARDATION IN BLACK-AND-WHITE CHILDREN IN METROPOLITAN ATLANTA - A CASE-CONTROL STUDY

Objectives. This study assessed differences in the prevalence of mild mental retardation, defined as an intelligence quotient (IQ) from 50 t o 70, between Black and White children. Methods. A case-control study design was used. Ten-year-old children with mental retardation were id entified from multiple sources. Information on race, sex, maternal age , birth order, economic status, and maternal education was abstracted from birth certificates of 330 case children and 563 control children (public school students). Results. The crude Black-White odds ratio (O R) was 2.6, but it was reduced to 1.8 after the other five covariates were controlled. The disparity was largest among children whose mental retardation was first diagnosed when they were 8 to 10 years old (adj usted OR = 2.5). We found no significant difference in the occurrence of mild mental retardation between Black and White children diagnosed before the age of 6 pears (adjusted OR = 1.2). Black children had a hi gher prevalence of mild mental retardation within all strata of the ot her five covariates. Conclusions. Five sociodemographic factors accoun ted for approximately half of the excess prevalence of mild mental ret ardation among Black children. Possible reasons for the residual diffe rence are discussed.