Trends and geographic variation of opiate medication use in state Medicaid fee-for-service programs, 1996 to 2002

Although studies have documented hospital and surgical service geographic variability, prescription use geographic variability is largely unknown. Opiate pain medications are widely used, particularly because the promulgation of clinical guidelines promoting aggressive pain treatment. This study describes temporal and interstate variability in aggregate prescription opiate medication use within U.S. Medicaid programs.

A dataset of 49 states' fee-for-service (FFS) Medicaid prescription drug dispensing records from 1996 to 2002 was compiled and used to quantify medication dispensing examining all opiates, controlled release oxycodone, and methadone. The defined daily dose (DDD) per 1000 FFS Medicaid adult enrollees per day was calculated for all opiate medication categories. A market basket of nonpain prescription medications was constructed for comparison. Rates, trends, and the coefficient of variation were determined overall, by year and for each state.

From 1996 to 2002, overall use of opiate pain medications increased 309%. The market basket use increased 170%. Total opiate dispensing varied widely from state to state, with a range of 6.9 to 44.1 DDD/1000/d in 1996, and 7.1 to 165.0 DDD/1000/d (a 23-fold difference) in 2002. The coefficient of variation was 49.6 in 2002. Controlled release oxycodone and methadone had a greater rate of increase compared with all opiates.

The dispensing of opiate medications in Medicaid programs increased at almost twice the rate of nonpain-related medications during the 7-year study period. Large, unexplained geographic variation in aggregate use exists. The impact of Medicaid cost-containment strategies on utilization and outcomes should be investigated.