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Significant Increases in Drug Co-Payments May Reduce Patients' Use of Needed Medications

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Press Release Date: May 18, 2004

Increasing patients' co-payments for prescription medications led to decreases in their use of eight classes of therapeutic drugs, according to a new study co-funded by the Agency for Healthcare Research and Quality.

Researchers linked pharmacy claims data representing nearly 530,000 people age 18 to 64, who all had employer-sponsored health insurance, with health benefit designs from 52 private health plans and 30 employers. The study included one-tier, two-tier, three-tier, and coinsurance drug benefit plans included in the study of all types. The simulated co-payment increases were relevant for all plans but were calibrated to two-tier plans. The analysis followed study subjects for nearly 4 years.

Based on this analysis, researchers estimated that doubling co-payments in a typical two-tier drug plan resulted in an approximately 45 percent reduction in the use of anti-inflammatory drugs and antihistamines, a drop of approximately 35 percent in the use of cholesterol-lowering medications and drugs to treat ulcers and asthma, and a decrease of about 25 percent in the use of medicines used to treat high blood pressure, depression, and diabetes.

The rate of decrease depended on whether patients were taking the drug on an ongoing or intermittent basis. Patients with chronic illnesses were less likely to cut back or stop taking the medications needed to treat their conditions when drug co-payments increased; however, they seemed to reduce their use of other medications. For example, the study found that patients with depression cut their use of most drugs by 25 percent but reduced their use of antidepressants by only 8 percent when their co-payments doubled. Similarly, patients with high blood pressure cut their use of antihypertensives by only 10 percent but reduced their use of all other drugs by 27 percent.

Researchers also found preliminary evidence that patient health suffers as individuals with some chronic illnesses cut back on their medicines. For example, as the use of prescription drugs declined, visits to hospital emergency rooms increased 17 percent and hospital stays rose by 10 percent among patients with diabetes, asthma, and gastric acid diseases.

"This study will give public and private policymakers rigorous science-based information to evaluate the impact that changes in cost sharing can have on patients' use of medications," said Carolyn M. Clancy, M.D., AHRQ's Director. "The article's findings suggest that policy solutions to reducing costs while maintaining quality cannot be 'one-size fits all' solutions, but must take into account the potential response of patients."

The research team was led by Drs. Dana P. Goldman and Geoffrey F. Joyce and their colleagues at the RAND Corporation in Santa Monica, CA, as well as by co-authors from Merck and California Healthcare Foundation. Both organizations also co-funded the study. Details are in "Pharmacy Benefits and the Use of Drugs by the Chronically Ill," published in the May 19, 2004, issue of the Journal of the American Medical Association.

For more information, please contact AHRQ Public Affairs: (301) 427-1855, or (301) 427-1863.


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