A review of the medical records of a group of elderly patients shows that only 32.9 percent took the drugs prescribed to treat high blood pressure and High cholesterol.

“This study emphasizes the importance of considering adherence when caring for high-risk older patients,” Dr. Richard H. Chapman commented to Reuters Health. “Despite the relatively high cardiovascular risk” of these patients, surprisingly few were adherent to prescribed medications.

Chapman of ValuMedics Research in Falls Church, Virginia, and colleagues conducted an analysis of data for 4,052 patients 65 years of age or older who were enrolled in the Protocare Sciences Managed Care Database. Drugs to lower high blood pressure and High cholesterol were initially prescribed within a 90-day period.

The researchers defined adherence as filling prescriptions to cover at least 80 percent of days of therapy to lower blood pressure and cholesterol. Adherence was evaluated at 3-month intervals, and the average follow-up was 19.5 months. The team reported the results at the American Heart Association’s 7th Scientific Forum on Quality of Care and Outcomes Research in Cardiovascular Diseases and Stroke, being held in Washington, D.C.

Chapman reported that adherence to both classes of drugs fell rapidly to 40.5 percent at the 3-month mark, then to 32.7 percent at 6 months, and stabilized at 32.9 percent at 1 year.

Patients tended to take more of one class of drug or the other, and the adherence rate to one drug at each time point was 27.8 percent to 35.0 percent higher than adherence to both. Adherence to blood pressure lowering drugs was generally higher than for cholesterol lowering drugs.

From the data in this study, it is not clear why adherence was lower with cholesterol-lowering drugs, Chapman said. The differences could be due to side effects or other factors. “For example, patients may believe that their high blood pressure is more of a problem than their High cholesterol.” However, “we have no way to tell this for sure from this study.”

The researchers also found that if both drugs were prescribed at the same time, adherence to both drugs was about 13 percent higher. Patients with pre-existing heart disease were also more motivated to take both medications as prescribed, and had an adherence rate that was about 27 percent higher than the other patients.

The factor associated with the lowest adherence to both drugs was having multiple prescriptions other additional medications.

Based on these findings, Chapman suggests that adherence could be improved by starting patients on high blood pressure and High cholesterol at the same time if possible. In addition, paying close attention to patients who are taking several drugs is a particularly important issue when the patient is elderly.