State implementation of laws that require health plans to cover treatment for substance abuse disorder (SUD) appears to increase the treatment rate, according to a study by Hefei Wen, B.A., of Emory University, Atlanta, Ga., and colleagues.

More than half the states in the U.S. have enacted parity laws mandating comparable coverage for medical and SUD because insurance coverage for SUD treatment can be more restrictive in terms of cost sharing and treatment limitations. An estimated 23 million Americans had a SUD in 2010, according to the study background.

Researchers analyzed all state-level SUD parity laws in the private insurance market that were implemented between October 2000 and March 2008 and found that implementing any SUD parity law increased the treatment rate a relative 9 percent in all specialty SUD treatment facilities and by 15 percent in facilities that accept private insurance.

"Our study provides useful information into the potential effect of the implementation and the comprehensiveness of SUD parity on access to SUD treatment and, in broad terms, the potential of financial incentives and policy leverage to influence treatment-seeking behavior," the authors conclude.