Psychiatric Hospitalization Among Adults With Intellectual and Developmental Disability

OBJECTIVE: The authors examined psychiatric hospitalizations among adults with mental illness, by intellectual and developmental disability (IDD) diagnosis. METHODS: MarketScan Multi-State Medicaid Database claims from 2016 to 2023 were used in measuring annual rates of psychiatric hospitalization among adults with mental illness with and without IDD and by IDD diagnosis. The authors made comparisons using generalized estimating equation models. RESULTS: A total of 2,718,432 adults with mental illness were identified in claims from 2016 to 2023; 5.1% (N=137,916) had IDD. Annual rates of psychiatric hospitalization were higher among those with IDD. In adjusted models, adults with IDD had decreased odds of psychiatric hospitalization (adjusted odds ratio=0.80, 95% CI=0.79-0.81, p<0.001). Factors associated with psychiatric hospitalization were consistent across groups. CONCLUSIONS: Despite higher rates of psychiatric hospitalization, adults with IDD are less likely to be hospitalized than other adults with the same clinical and demographic characteristics.