Incremental Utility of 24-Month Autism Spectrum Disorder Screening After Negative 18-Month Screening.

The late-diagnosed group had only 10 children, so comparisons with the 203 early-diagnosed children are unstable. Twelve of the 32 children who screened positive at 24 months did not attend an evaluation, so their diagnostic status is unknown. The 80% diagnosis rate among evaluated children may be an over- or under-estimate if extrapolated to all children who screened positive at 24 months. Children who screened negative at 18 months were not systematically evaluated then, so the study cannot tell whether symptoms emerged later or were missed. The overwhelming majority of the sample was White, and community practices may not administer the Follow-Up telephone interview as the research team did. Household income was missing for 60% of the late-diagnosed group and 35% of the early-diagnosed group. The ADOS severity difference was small and not supported by the CARS, so it may be a measurement artifact.

The study used data from a federally funded early detection study. Diana Robins and Deborah Fein are co-owners of M-CHAT LLC, which receives royalties from companies that incorporate the M-CHAT into commercial products. The data used are from the freely available version. The remaining authors declared no conflict.

Do not treat a negative 18-month autism screen as ruling out autism. In this study, 0.4% of children who were rescreened at 24 months screened positive, and 10 were diagnosed with autism; 12 of the 32 children who screened positive at 24 months were not evaluated.