An adherence self-report questionnaire facilitated the differentiation between nonadherence and nonresponse to antihypertensive treatment

ObjectivesTo evaluate, among hypertensive patients, a brief adherence self-report questionnaire (ASRQ), using electronic monitors (medical event monitoring system, MEMS) as the gold standard comparator.Study Design and SettingA total of 239 patients with hypertension in five general practices in Bristol, UK completed the ASRQ before and at the end of the 4-week study period. Patients were asked to choose one of six descriptions (from level 1 = perfect adherence to level 6 = nonadherence) to express their medication taking. The main outcome measure was “timing adherence” (correct interdose intervals) as measured through electronic monitors.ResultsMost patients (89%) stated perfect or nearly perfect adherence, and data from the electronic monitors showed a mean timing adherence of 88.3% (n = 216). Using the cutoff of those who reported ASRQ levels 1 and 2 (all tablets taken but not always at the same time of day), a high percentage of those with comparatively high adherence according to MEMS were correctly identified (specificity, 90–93%; negative predictive value, 66–96%). However, sensitivity (detection of true nonadherers) and positive predictive value were poor to moderate (14–42% and 22–66%, respectively).ConclusionThe questionnaire could be a useful aid to facilitate the difficult differentiation between nonadherence and nonresponse to prescribed antihypertensive medication.