Evaluation of a records-review surveillance system used to determine the prevalence of autism spectrum disorders.

We conducted the first study that estimates the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of a population-based autism spectrum disorders (ASD) surveillance system developed at the Centers for Disease Control and Prevention. The system employs a records-review methodology that yields ASD classification (case versus non-ASD case) and was compared with classification based on clinical examination. The study enrolled 177 children. Estimated specificity (0.96, [CI(.95) = 0.94, 0.99]), PPV (0.79 [CI(.95) = 0.66, 0.93]), and NPV (0.91 [CI(.95) = 0.87, 0.96]) were high. Sensitivity was lower (0.60 [CI(.95) = 0.45, 0.75]). Given diagnostic heterogeneity, and the broad array of ASD in the population, identifying children with ASD is challenging. Records-based surveillance yields a population-based estimate of ASD that is likely conservative.