Access to substance abuse treatment services under the Oregon Health Plan

Context: The shift to Medicaid managed care has raised numerous concerns about access to publicly funded substance abuse treatment. The implementation of a capitated chemical dependency benefit within the Oregon Health Plan in 1995 provided an opportunity to study the impact of funding mechanisms on access. Objectives: To determine to what extent access to publicly funded substance abuse treatment changed following the shift to managed care in Oregon and to examine factors associated with that change. Design: Analysis of statewide treatment and Medicaid eligibility data. Setting and Patients: All Medicaid-eligible persons aged 12 to 64 years who were enrolled in the Oregon Health Plan during 1994 (88320), 1996 (170387), 1997 (160929), or 1998 (149877). Main Outcome Measures: Access rates (the number of unique individuals admitted to treatment during a calendar year divided by the average number of enrolled members) computed before (1994) and after (1997) implementation of the capitated benefit. Analyses were replicated with data for 1996 and 1998. Results: The percentage of Medicaid-eligible persons admitted to substance abuse treatment programs during a calendar year increased from 5.5% of the average number of enrolled members per month in 1994 to 7.7% in 1997, following the shift to managed care. For 1996 and 1998, the rates were 6.9% and 7.7%, respectively. Access rates varied considerably among the 7 largest prepaid health plans after adjusting for case mix. Operating characteristics of these prepaid health plans, such as the method of reimbursing treatment providers, were significant predictors of access after controlling for member characteristics. Conclusion: According to our analyses, Medicaid-eligible persons in Oregon observed an increase in access to substance abuse treatment after a shift to managed care.