Increase in prescription drug cost sharing associated with lower rates of drug treatment, adherence

Jul 4 2007

A review of previous studies indicates that an increase in prescription drug cost sharing is associated with a decrease in drug spending and use of pharmacies; and for some chronic conditions, higher cost sharing is associated with greater use of expensive medical services, according to an article in the July 4 issue of JAMA: The Journal of the American Medical Association.

"'With recent increases in pharmacy spending, pharmacy benefit managers and health plans have adopted benefit changes designed to reduce pharmaceutical use or steer patients to less-expensive alternatives. The rapid proliferation of mail-order pharmacies, mandatory generic substitution, coinsurance plans, and multitiered formularies has transformed the benefit landscape," the authors write.

Dana P. Goldman, Ph.D., of RAND, Santa Monica, Calif., and colleagues analyzed previous studies to determine how cost-sharing features of prescription drug benefits may affect access to prescription drugs and how these features may affect medical spending and health outcomes. For this analysis, the researchers identified 132 articles examining the associations between prescription drug plan cost-containment measures, including co-payments, tiering, or coinsurance, pharmacy benefit caps or monthly prescription limits, formulary restrictions, and reference pricing, and outcomes, including pharmacy utilization and spending, medical care utilization and spending, and health outcomes.

"Increased cost sharing is associated with lower rates of drug treatment, worse adherence among existing users, and more frequent discontinuation of therapy. For each 10 percent increase in cost sharing, prescription drug spending decreases by 2 percent to 6 percent, depending on class of drug and condition of the patient. The reduction in use associated with a benefit cap, which limits either the coverage amount or the number of covered prescriptions, is consistent with other cost-sharing features," the researchers write.

"For some chronic conditions, higher cost sharing is associated with increased use of medical services, at least for patients with congestive heart failure, lipid disorders, diabetes, and schizophrenia. While low-income groups may be more sensitive to increased cost sharing, there is little evidence to support this contention."

"These findings make benefit design an important public health tool for improving population health. The challenge for public and private plans is to make patients more sensitive to the cost of treatment without encouraging them to forego cost-effective care. This requires knowing how patients respond to different incentives and cataloging the net benefits of alternative therapies, not only for health, but also for current and future health care costs, productivity, and patient utility," the authors conclude.

http://jama.ama-assn.org/