Evaluation of an innovative Medicaid health policy initiative to expand substance abuse treatment in Washington State.

State health policy making is rarely based on evidence derived from empirical analysis. An exception is an innovative policy established in 2005 in Washington State (Senate Bill [SB] 5763) to provide funding (approximately $30 million) to expand access to substance abuse (SA) treatment for Medicaid beneficiaries. The authors analyzed Medicaid claims data and other administrative data over a 7-year period, July 2001 through June 2008, for three cohorts of welfare clients (n ≈ 44,000) to assess the effect of SA treatment on health care expenditures. Regression analysis showed SA treatment to be associated (p < .001) with per member per month expenditure savings of approximately $160 to $385 depending on the welfare cohort. The aggregate annualized estimated saving ($16.8 million) equaled the cost-saving goal of SB 5763. While it may be tempting for policy makers to cut funding for SA treatment, this may be counterproductive and in the long-run increase Medicaid costs.