Medicaid prescription formulary restrictions and arthritis treatment costs

Objectives. We used the Arizona Medicaid program as a model to examine the consequences of the relative restrictiveness of nonsteroidal anti-inflammatory drug (NSAID)-preferred drug lists on health care use and costs for Medicaid enrollees with arthritis. Methods. In a retrospective, cross-sectional study of Medicaid enrollees with rheumatoid arthritis or osteoarthritis, we used data from the Arizona HealthQuery database and generalized linear regression models to estimate the effect of the restrictiveness of formularies on the association between number of NSAID drugs covered and the number of emergency department visits, ambulatory physician visits, hospital stays, and total health expenditures. Results. For plans with NSAID formularies that were more restrictive, enrollees with rheumatoid arthritis experienced 22% fewer ambulatory visits and 29% more hospitalizations, and enrollees with osteoarthritis experienced 38% fewer ambulatory visits and 52% more hospitalizations. These plans spent an additional $935 for medical care and prescription drugs annually per enrollee with rheumatoid arthritis. Conclusions. Formularies that are more restrictive significantly change the patterns of health care and prescription drug use and may have unintended consequences in terms of more frequent and, for those with rheumatoid arthritis, more expensive medical care.