Clinical Summary: County-Level Variation in Substance Use Disorder Service Utilization by Insurance Payers and Self-Pay in the United States
Most people who need substance use disorder treatment still do not receive it, and where a patient lives may strongly shape whether care is accessed through Medicaid, private insurance, or self-pay. This study quantifies how sharply SUD service use varies across US counties and shows that insurance coverage—especially the local uninsured rate—is one of the strongest markers of whether treatment is actually used.
Key Findings
- Across examined payers, annual SUD service expenditures averaged $31 billion during 2017–2019; Medicaid paid 52.7% of SUD service expenditures while accounting for 18.4% of overall health care expenditures and 37.7% of SUD service utilizations.
- Self-pay accounted for 43.0% of SUD service utilizations but only 5.1% of SUD service expenditures, while private insurance covered 32.3% of SUD service expenditures and represented 12.9% of SUD service utilizations.
- Across 3,143 US counties during 2017–2019, the average annual county-level number of SUD health service utilizations from examined payers was 5.2 (95% CI = 5.1–5.3) per 1,000 county residents; 23.3% of counties had <3.0 per 1,000 county residents and 9.3% had ≥10.0 per 1,000 county residents.
- Counties in the top 20% had 10.4 (95% CI = 10.2–10.6) SUD utilizations per 1,000 county residents versus 2.5 (95% CI = 2.5–2.5) in the bottom 20%, a 4.2-fold difference; the percentage of uninsured adults was 19.7% (95% CI = 19.2%–20.3%) in the bottom 20% versus 9.3% (95% CI = 9.1%–9.6%) in the top 20%.
- In Model 4, the county-level percentage of uninsured adults was negatively associated with county-level SUD health service utilization overall (β = −.45, P<.0001), for self-pay (β = −.40, P < .0001), for Medicaid (β = −.46, P < .0001), and for private insurance (β = −.14, P < .0001); Model 4 explained 57.5% of variance overall, 47.3% for self-pay, 58.0% for Medicaid, and 31.1% for private insurance.
Insurance coverage is a major determinant of whether SUD services are used at the county level, with uninsured rates showing a stronger relationship to SUD treatment utilization than many other socioeconomic or health care resource measures. Medicaid is carrying a disproportionate share of SUD treatment financing, while self-pay remains a strikingly large pathway into care.
Practice Implications
- In counties with high uninsured rates, expect lower SUD service utilization and consider insurance enrollment and coverage stabilization as part of treatment access strategy, not just social support.
- Do not assume insured patients account for most observed SUD encounters: self-pay represented 43.0% of SUD service utilizations, so clinicians and systems should ask directly about out-of-pocket barriers and cash-pay treatment pathways.
- Medicaid played a disproportionately large role in funding SUD services, paying 52.7% of SUD service expenditures while accounting for 18.4% of overall health care expenditures; county planning for SUD treatment capacity should account for Medicaid’s central financing role.
- When planning county-level SUD services, use payer-specific patterns rather than general medical utilization assumptions, because Model 4 explained 57.5% of SUD utilization variance versus 20.2% for overall health conditions.
