ATLANTA — Adherence to concomitant lipid-lowering and antihypertensive medications falls by an average of 9% with each additional background prescription drug a patient is on, Joshua S. Benner, Pharm.D., said at the annual meeting of the American College of Cardiology.
However, the relationship between the number of other drugs a patient is taking and adherence to antihypertensive and lipid-lowering drugs is curvilinear, not linear: The decline in adherence is steepest in patients already on up to three other medications at baseline, and it flattens out somewhat in those on four or more other drugs, according to Dr. Benner of ValueMedics Research, Falls Church, Va.
“Pill burden matters most for the patients who take the fewest additional number of medications,” he said.
Dr. Benner presented a retrospective cohort study of patients enrolled in a large managed care plan. The study measured adherence to concomitant antihypertensive and lipid-lowering therapy and identifying predictors of treatment adherence. It involved 5,759 patients placed on both such medications within a 90-day period.
Adherence was poor overall, with 36% of patients remaining adherent to both therapies at 12 months' follow-up. Adherence was defined as having filled prescriptions for both medications on at least 80% of the days of follow-up.
Another predictor of adherence was initiating antihypertensive and lipid-lowering therapy together. After adjustment for comorbidities and demographic variables, patients who started the second therapy within 30 days of the first were 54% more likely to be adherent to both than were those who initiated the second therapy within 61–90 days. Sex and age were also closely linked to adherence. Women were 20% less likely than men to adhere to both drugs at 1 year. Patients aged 55–64 were 76% more likely and 65- to 74-year-olds were 37% more likely to be adherent than were those aged 18–44 years.