County-Level Variation in Substance Use Disorder Service Utilization by Insurance Payers and Self-Pay in the United...

Objectives: To examine county-level variations in and correlates of substance use disorders (SUDs) health service utilization by insurance payers (Medicaid, private insurance, and Medicare) and self-pay.

Methods: Service utilization (the number of health care encounters, visits, admissions, or prescriptions) for SUDs was extracted from the Disease Expenditure 2017-2019 Project. We linked county-level data to drug overdose mortality rates and County Health Rankings, Area Health Resources Files, and Opioid Environment Policy Scan datasets. Descriptive and regression analyses were applied.

Results: During 2017-2019, Medicaid (52.7%) and private insurance (32.3%) financed 85.0% of annual average SUD service expenditures examined, accounting for 50.6% of SUD service utilizations (in number). Across 3,143 counties, the average annual county-level number of SUD service utilizations was 5.2 (95% CI =5.1-5.3) per 1,000 county residents. Self-pay individuals had the highest average county-level number of SUD service utilizations (8.6, 95% CI =8.4-8.6 per 1,000 county residents), followed by Medicaid beneficiaries (6.9, 95% CI =6.6-7.1 per 1,000 county Medicaid enrollees) and those paid by private insurance (2.8, 95% CI =2.7-2.8 per 1,000 privately insured county residents). County-level percentage of uninsured adults was negatively associated with SUD service utilization overall (standardized β = -.45, the highest across examined variables, P<.0001), accounting for 23.0% of its variance. SUD-related health care resource indicators explained 2.3%.

Conclusions: Across all examined payers, Medicaid funded a disproportionate share-over 50%-of SUD service expenditures. Findings quantified the substantial impact of county-level adult uninsured rates on SUD health service utilization, highlighting the pivotal role of health insurance in supporting access to and utilization of SUD services.