Within Six Months, One In Three Patients Fail To Take Medications As Prescribed

Patients with both high blood pressure and dyslipidemia (high lipid levels), are at substantially greater risk of coronary heart disease (CHD) events, such as heart attack, than those with either condition alone, according to background information in the article. The current study was designed to study how well patients with both conditions adhere to a drug regimen including both anti-hypertensive (AH, blood pressure lowering) and lipid-lowering (LL) medications.

Richard H. Chapman, Ph.D., of ValueMedics Research, L.L.C., Arlington, Va., and colleagues examined the database from a managed care organization to identify patients who had been prescribed both anti-hypertensive and lipid-lowering medications within a period of 90 days between January 1, 1997, and January 30, 2001. Adherence to concomitant therapy (taking both medications) was established at three, six and 12 months following treatment start on the basis of prescriptions filled. Patients were considered to be taking their drugs as prescribed if they had filled prescriptions sufficient to cover at least 80 percent of days of both classes of medications.

A total of 8,406 patients were followed for an average of 12.9 months. The percentage of patients adhering to both anti-hypertensive and lipid-lowering declined sharply over the course of the study, with 44.7 percent maintaining their treatment regimen at three months, 35.9 percent at six months and 35.8 percent at twelve months. At each time interval, an additional 25.3 to 29.6 percent were taking one, but not both, drugs as prescribed.

The strongest predictor of taking both medications as prescribed was the number of other prescriptions the patient was taking in the year before treatment was initiated, the researchers found. As the number of other prescribed medications decreased, the likelihood of adherence to concomitant anti-hypertensive and lipid-lowering therapy increased. The second strongest predictor of adherence was age. The third strongest predictor was the time between the initiations of the two treatments. Patients who started these regimens on the same day or within one month of each other were 34 percent more likely to be adherent with both medications during the three-year study period, compared with patients who initiated therapy two to three months apart. Women were less likely to be adherent than men.

"... physicians may be able to improve medication adherence substantially by reducing the number of concomitant medications and by initiating AH and LL medications together or close in time," the authors conclude. "Any improvement in adherence with concomitant AH and LL medications is likely to be associated with substantial public health care benefits."

(Arch Intern Med. 2005; 165:1147-1152. Available post-embargo at www.archinternmed.com.)

Editor's Note: This study was supported by a grant from Pfizer Inc., New York, N.Y. ValueMedics Research, L.L.C., has received payments for research and consulting from Pfizer Inc. J. Sanford Schwartz, M.D., a co-author of the study, has received research support from and does consulting for Pfizer, Inc.