Developmental screening tests, even those meeting standards for screening test accuracy, produce numerous false-positive results for 15% to 30% of children. This is thought to produce unnecessary referrals for diagnostic testing or special services and increase the cost of screening programs.
To explore whether children who pass screening tests differ in important ways from those who do not and to determine whether children overreferred for testing benefit from the scrutiny of diagnostic testing and treatment planning.
Subjects were a national sample of 512 parents and their children (age range of the children, 7 months to 8 years) who participated in validation studies of various screening tests. Psychological examiners adhering to standardized directions obtained informed consent and administered at least 2 developmental screening measures (the Brigance Screens, the Battelle Developmental Inventory Screening Test, the Denver-II, and the Parents' Evaluations of Developmental Status) and a concurrent battery of diagnostic measures, including tests of intelligence, language, and academic achievement (for children aged 2½ years and older). The performance on diagnostic measures of children who failed screening but were not found to have a disability (false positives) was compared with that of children who passed screening and did not have a disability on diagnostic testing (true negatives).
Children with false-positive scores performed significantly (P<.001) lower on diagnostic measures than did children with true-negative scores. The false-positive group had scores in adaptive behavior, language, intelligence, and academic achievement that were 9 to 14 points lower than the scores of those in the true-negative group. When viewing the likelihood of scoring below the 25th percentile on diagnostic measures, children with false-positive scores had a relative risk of 2.6 in adaptive behavior (95% confidence interval [CI], 1.67-4.21), 3.1 in language skills (95% CI, 1.90-5.20), 6.7 on intelligence tests (95% CI, 3.28-13.50), and 4.9 on academic measures (95% CI, 2.61-9.28). Overall, 151 (70%) of the children with false-positive results scored below the 25th percentile on 1 or more diagnostic measures (the point at which most children have difficulty benefiting from typical classroom instruction) in contrast with 64 (29%) of the children with true-negative scores (odds ratio, 5.6; 95% CI, 3.73-8.49). Children with false-positive scores were also more likely to be nonwhite and to have parents who had not graduated from high school. Performance differences between children with true-negative scores and children with false-positive scores continued to be significant (P<.001) even after adjusting for sociodemographic differences between groups.
Children overreferred for diagnostic testing by developmental screens perform substantially lower than children with true-negative scores on measures of intelligence, language, and academic achievement—the 3 best predictors of school success. These children also carry more psychosocial risk factors, such as limited parental education and minority status. Thus, children with false-positive screening results are an at-risk group for whom diagnostic testing may not be an unnecessary expense but rather a beneficial and needed service that can help focus intervention efforts. Although such testing will not indicate a need for special education placement, it can be useful in identifying children's needs for other programs known to improve language, cognitive, and academic skills, such as Head Start, Title I services, tutoring, private speech-language therapy, and quality day care.