title: Validation of the Adherence Barriers Questionnaire - an instrument for identifying potential risk factors associated with medication-related non-adherence.
abstract: BACKGROUND
  Medication non-adherence is a major challenge in the real-life treatment of chronically ill patients. To meet this challenge, adherence interventions with a tailored approach towards patient-specific adherence barriers that are identified with a reliable and practicable questionnaire are needed. The aim of this investigation was to develop and validate such a questionnaire, the "Adherence Barriers Questionnaire (ABQ)".
  
  
  METHODS
  The German ABQ was developed and tested in 432 patients with atrial fibrillation in a multicentre observational cohort study. Evaluation of the questionnaire included an assessment of internal consistency as well as factor analysis. Criterion-related external validity was assessed by comparing the ABQ score with (1) the degree of self-reported adherence and (2) the time in therapeutic range which describes the anticoagulation quality achieved by patients treated with oral anticoagulation.
  
  
  RESULTS
  The final 14-item ABQ scale demonstrated high internal consistency (Cronbach's alpha = 0.820). Factor analysis identified a three-factor solution, representing intentional adherence barriers with 5 items (31.9% of the variance), medication-/health care system-related adherence barriers with 5 items (13.3% of the variance) and unintentional adherence barriers with 4 items (7.7% of the variance). The ABQ correlated significantly with self-reported non-adherence (Spearman's rho = 0.438, p < 0.001) as well as time in therapeutic range (Spearman's rho = - 0.161, p < 0.010). Patients with above-average ABQ scores (increased number and/or strength of existing adherence barriers) were significantly (p < 0.005, Pearson Chi-Square) more likely to have a poor anticoagulation quality (TTR < 60%) than patients with a lower ABQ score (44.6% versus 27.3%).
  
  
  CONCLUSIONS
  The ABQ is a practicable, reliable and valid instrument for identifying patient-specific barriers to medication-related adherence. Future research is required to examine the ability of the ABQ to identify patient perception/behaviour changes over time which may be important for the measurement of success of adherence interventions.
authors.affiliation: Institut für Pharmakoökonomie und Arzneimittellogistik (IPAM), Hochschule Wismar, Philipp-Müller-Straße 12, Wismar, 23966, Germany. sabrina.mueller@ipam-wismar.de.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Müller
authors.affiliation: Institut für Community Medicine, Universitätsmedizin Greifswald, Greifswald, Germany. thomas.kohlmann@uni-greifswald.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kohlmann
authors.affiliation: Institut für Pharmakoökonomie und Arzneimittellogistik (IPAM), Hochschule Wismar, Philipp-Müller-Straße 12, Wismar, 23966, Germany. thomas.wilke@ipam-wismar.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wilke
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy*; D002908:Chronic Disease / Q000188:drug therapy* / Q000523:psychology*; D015331:Cohort Studies; D005163:Factor Analysis, Statistical; D005260:Female; D005858:Germany; D006801:Humans; D008297:Male; D055118:Medication Adherence / Q000523:psychology*; D008875:Middle Aged; D064887:Observational Studies as Topic; D015203:Reproducibility of Results; D012307:Risk Factors; D057566:Self Report; D011795:Surveys and Questionnaires; D016903:Drug Monitoring
chemical_list: D000925:Anticoagulants