Adverse Effects of Complementary and Alternative Medicine on Antihypertensive Medication Adherence: Findings from the Cohort Study of Medication Adherence Among Older Adults

OBJECTIVES To determine the association between complementary and alternative medicine (CAM) use and antihypertensive medication adherence in older black and white adults. DESIGN Cross-sectional. SETTING Patients enrolled in a managed care organization. PARTICIPANTS Two thousand were hundred eighty black and white adults aged 65 and older and prescribed antihypertensive medication. MEASUREMENTS Information on CAM use (health food and herbal supplements, relaxation techniques) for blood pressure control and antihypertensive medication adherence were collected in a telephone survey between August 2006 and September 2007. Low medication adherence was defined as a score less than 6 using the eight-item Morisky Medication Adherence Scale. RESULTS The mean age of participants was 75.0 +/- 5.6, 30.7% were black, 26.5% used CAM, and 14.1% had low antihypertensive medication adherence. In managing blood pressure, 30.5% of black and 24.7% of white participants had used CAM in the last year (P=.005), and 18.4% of black and 12.3% of white participants reported low adherence to antihypertensive medication (<.001). After multivariable adjustment for sociodemographic information, depressive symptoms, and reduction in antihypertensive medications because of cost, the prevalence ratios of low antihypertensive medication adherence associated with CAM use were 1.56 (95% confidence interval (CI)=1.14-2.15; P=.006) in blacks and 0.95 (95% CI=0.70-1.29; P=.73) in whites (P value for interaction=.07). CONCLUSION In this cohort of older managed care patients, CAM use was associated with low adherence to antihypertensive medication in blacks but not whites.