Importance: The American Academy of Pediatrics recommends referring children at elevated risk of autism spectrum disorder (ASD) for Part C early intervention (EI) services, but notes that EI services often fail to provide ASD screening.
Objective: To evaluate the hypothesis that a multistage screening protocol for ASD implemented in 3 EI settings will increase autism detection, especially among Spanish-speaking families.
Design, setting, and participants: Difference-in-differences analyses with propensity score weighting of a quasi-experimental design using administrative data on 3 implementation EI agencies and 9 comparison EI agencies from 2012 to 2018 provided by the Massachusetts Department of Public Health. Eligible children were aged 14 to 36 months, enrolled in EI, had no prior ASD diagnosis or medical condition precluding participation, and had parents who spoke English or Spanish. The final analytic sample included 33 326 unique patients assessed across 150 200 person-quarters.
Exposures: Multistage ASD assessment protocol including ASD screening questionnaires, observational screener, and diagnostic evaluation.
Main outcomes and measures: Increased incidence of ASD diagnoses as documented in Department of Public Health records and reductions in language-associated health care disparities.
Results: Implementation of screening at 3 EI sites was associated with a significant increase in the rate of ASD diagnoses (incidence rate ratios [IRR], 1.6; 95% CI, 1.3-2.1; P < .001), representing an additional 8.1 diagnoses per 1000 children per quarter. Among Spanish-speaking families, screening was also associated with a significant increase in the rate of ASD diagnoses (IRR, 2.6; 95% CI, 1.6-4.3; P < .001), representing 15.4 additional diagnoses per 1000 children per quarter-a larger increase than for non-Spanish-speaking families (interaction IRR, 1.8; 95% CI, 1.0-3.1; P = .005). Exploratory analyses revealed that screening was associated with a larger increase in the rate of ASD diagnoses among boys (IRR, 1.8; 95% CI, 1.4-2.3; P < .001) than among girls (IRR, 1.1; 95% CI, 0.6-1.7; P = .84).
Conclusions and relevance: In this study, associations between increased rates of ASD diagnoses and reductions in disparities for Spanish-speaking households support the effectiveness of multistage screening in EI. This study provides a comprehensive evaluation of ASD screening in EI settings as well as a rigorous evaluation of ASD screening in any setting with a no-screening comparison condition. Given that the intervention included multiple components, mechanisms of action warrant further research, as do disparities by child sex.