Factors associated with false-positive self-reported adherence to antihypertensive drugs

Self-reported medication adherence is known to overestimate true adherence. however, little is known about patient factors that may contribute to the upward bias in self-reported medication adherence. the objective of this study is to examine whether demographic, behavioral, medication and mood factors are associated with being a false-positive self-reported adherer (fpa) to antihypertensive drug treatment. we studied 175 patients (mean age: 50 years; 57% men) from primary-care clinics starting antihypertensive drug treatment. self-reported adherence (sra) was measured with the medication adherence report scale (mars) and by the number of drug doses missed in the previous week/month, and compared with pill count adherence ratio (pcar) as gold standard. data on adherence, demographic, behavioral, medication and mood factors were collected at baseline and every 3 months up to 1 year. fpa was defined as being a non-adherer by pcar and an adherer by self-report. mixed effect logistic regression was used for the analysis. twenty percent of participants were fpa. anxiety increased (odds ratio (or): 3.00; p=0.01), whereas smoking (or: 0.40; p=0.03) and drug side effects (or: 0.46, p=0.03) decreased the probability for fpa by mars. education below high-school completion increased the probability of being an fpa as measured by missing doses in the last month (or: 1.66; p=0.04) and last week (or: 1.88; p=0.02). the validity of sra varies significantly according to drug side effects, behavioral factors and patient’s mood. careful consideration should be given to the use of self-reported measures of adherence among patients likely to be false-positive adherers.