Early and Repeated Screening Detects Autism Spectrum Disorder.

Objective: To evaluate timing and accuracy of early and repeated screening for autism spectrum disorder (ASD) during well-child visits.

Study Design: Using a longitudinal study design, toddlers (n = 5784) were initially screened at 12 (n = 1504), 15 (n = 1228), or 18 (n = 3052) months during well-child visits, and rescreened at 18, 24, and 36 months. Of those screened, 368 toddlers attended an ASD evaluation after a positive screen and/or a provider concern for ASD at any visit.

Results: Screens initiated at 12 months yielded an ASD diagnosis significantly earlier than at 15 months (P = .003, d = 0.99) and 18 months (P < .001, d = 0.97). Cross-group overall sensitivity of the initial screen was .715 and specificity was .959. Repeat screening improves sensitivity (82.1%), without notably decreasing specificity (all >93.5%). Screening at 18 months resulted in significantly higher positive predictive value than at 12 months (X (1, n = 221) = 9.87, P = .002, OR = 2.60) and 15 months (X (1, n = 208) = 14.57, P < .001, OR = 3.67). With repeat screening, positive predictive value increased for all screen groups, but the increase was not significant.

Conclusions: Screening as early as 12 months effectively identifies many children at risk for ASD. Children screened at 12 months receive a diagnosis of ASD significantly earlier than peers who are first screened at later ages, facilitating earlier intervention. However, as the sensitivity is lower for a single screen, screening needs to be repeated.