Adherence to antihypertensive medication assessed by self-report was associated with electronic monitoring compliance

Background and Objective: Clinicians often find it difficult to differentiate between subobtimal adherence and nonresponse to medical treatment if a patient's clinical condition does not improve. This study aimed to evaluate an adherence self-report tool to assess adherence to blood pressure lowering medication. Study Design and Setting: Participants were 245 patients with uncontrolled hypertension from 21 general practices taking part in a randomized trial. Prior to randomization, participants were asked to indicate which of six descriptions (adherence levels) would most closely describe their medication taking and were given electronic medication monitors for 30 days. We used multivariable regression analysis to compare the adherence self-report tool with electronic monitoring. Results: There was strong evidence that a drop in one adherence level from level 1 (highest level) to level 2 and from level 2 to level 3-6 (six being the lowest) combined was associated with a decrease in timing compliance of similar to 5% (test for trend: P = 0.0004). Conclusion: Adherence assessed by a brief self-report tool was associated with timing compliance obtained through electronic monitoring in patients taking blood pressure lowering medication. Further research is required to investigate the validity of this tool in patients with lower adherence levels and in a nontrial population. (C) 2006 Elsevier Inc. All rights reserved.