Mental health service utilization among people with intellectual and developmental disabilities and serious mental illness before and during the emergence of telehealth services

Introduction: Few populations face more disadvantage than those with lifelong intellectual and developmental disabilities (IDD) and those with serious mental illness (SMI). People with IDD may face unique challenges in the manifestation and treatment of SMI; little is known about these challenges during the widespread expansion of telehealth mental health services during the COVID-19 pandemic which disrupted service availability. Methods: Using Medicaid claims from Kansas, Massachusetts, New York and South Carolina, mental health service utilization patterns for three cohorts of people ages 1-45 years were studied: those with IDD, those with SMI, and those with SMI and IDD. Utilization was examined before (2018-2019) and during (2020-2021) the emergence of telehealth services for each cohort. Meta-analysis was used to compare odds of mental health service utilization by demographic subgroups. Results: The prevalence of mental health service utilization was approximately 75% for the IDD/SMI cohort, 60% for the SMI cohort, and 30% of the IDD cohort in 2018. Teens 13-17 years and young adults tended to have the highest levels of service utilization. Service utilization was driven by different diagnoses for the groups. The SMI cohort utilized services significantly more for mood and anxiety disorders, and the IDD cohort utilized services significantly more for comorbid neurodevelopmental conditions, anxiety, and trauma-related disorders. The IDD/SMI cohort utilized services more bipolar and related disorders and had a younger median age of service utilizers for trauma- and stress-related disorders than the SMI cohort. Discussion: The IDD/SMI cohort had the highest mental health service utilization rates compared to the other two cohorts, with minimal urban-rural differences, suggesting mental health services may be reaching those at the highest levels of risk for adverse outcomes. People with IDD demonstrated substantially lower rates of telehealth utilization for mental health needs; however, people in the cohort with IDD and SMI demonstrated similar or higher rates (in adults) of telehealth utilization compared to people with SMI only. Even with expanded telehealth services, the COVID-19 pandemic appeared to partially disrupt utilization across all cohorts and age groups. Findings suggest that people with IDD and SMI experience trauma- and stressor-related disorders that require treatment at younger ages than people with SMI only.