title: An adherence self-report questionnaire facilitated the differentiation between nonadherence and nonresponse to antihypertensive treatment.
abstract: OBJECTIVE
  To evaluate, among hypertensive patients, a brief adherence self-report questionnaire (ASRQ), using electronic monitors (medical event monitoring system, MEMS) as the gold standard comparator.
  
  
  METHODS
  A 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.
  
  
  RESULTS
  Most 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).
  
  
  CONCLUSIONS
  The questionnaire could be a useful aid to facilitate the difficult differentiation between nonadherence and nonresponse to prescribed antihypertensive medication.
authors.affiliation: Academic Unit of Primary Health Care, Department of Community Based Medicine, University of Bristol, Cotham House, Cotham Hill, BS6 6JL Bristol, United Kingdom. zellera@uhbs.ch
authors.forename: Andreas
authors.initials: A
authors.lastname: Zeller
authors.forename: Knut
authors.initials: K
authors.lastname: Schroeder
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Peters
mesh_terms: D000368:Aged; D000959:Antihypertensive Agents / Q000008:administration & dosage*; D004812:Epidemiologic Methods; D005194:Family Practice; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*; D011320:Primary Health Care; D012646:Self Administration / Q000706:statistics & numerical data; D012650:Self Disclosure; D016896:Treatment Outcome
chemical_list: D000959:Antihypertensive Agents