title: Accuracy of the Medication Adherence Report Scale (MARS-5) as a quantitative measure of adherence to inhalation medication in patients with COPD.
abstract: BACKGROUND
  Self-report is considered most suitable to measure medication adherence in routine clinical practice. However, accuracy of self-report as a quantitative measure of adherence is not well documented.
  
  
  OBJECTIVE
  To assess the accuracy of a self-report measure of adherence (Medication Adherence Report Scale [MARS-5]) for identifying nonadherent users of inhalation medication among patients with chronic obstructive pulmonary disease (COPD), compared with medication refill adherence (MRA) as reference.
  
  
  METHODS
  We used baseline data from the Pharmaceutical Care for Patients with COPD (PHARMACOP)-trial (n = 734). Patients with incomplete MARS-5 and/or incomplete pharmacy refill records were excluded (n = 121). Internal consistency of MARS-5 (Crohnbach α) and Spearman rank correlation (ρ) with MRA were calculated. Different thresholds for nonadherence were used to calculate sensitivity, specificity, and positive predictive value (PPV), compared with dichotomized MRA (MRA ≥80% = adherent). A receiver operating characteristic (ROC) curve was plotted to determine the goodness of test.
  
  
  RESULTS
  613 patients were included in the analysis. The mean adherence score by MARS-5 (range = 5-25) was 23.5 (SD = 2.6); mean adherence by MRA was 83.4% (SD = 23.8%). Internal consistency of MARS-5 was high (α = 0.77). Continuous MARS-5 scores correlated poorly with continuous MRA scores (ρ = 0.10; P = 0.011). When lowering the nonadherence threshold stepwise from 25 to 20, MARS-5 did not reach sufficient sensitivity (53% to 13%), specificity (57% to 94%), and PPV (42% to 57%) to detect nonadherers compared with dichotomized MRA. ROC curve plotting resulted in an area under the curve value of 0.56 (95% CI = 0.521-0.616; P = 0.005).
  
  
  CONCLUSIONS
  Self-reported adherence measured by MARS-5 is inaccurate in identifying nonadherence to inhalation medication in patients with COPD.
authors: Pharmaceutical Care Unit, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium.
authors: Eline
authors: E
authors: Tommelein
authors: Els
authors: E
authors: Mehuys
authors: Inge
authors: I
authors: Van Tongelen
authors: Guy
authors: G
authors: Brusselle
authors: Koen
authors: K
authors: Boussery
mesh_terms: D000280:Administration, Inhalation; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy*; D057566:Self Report; D011795:Surveys and Questionnaires; D016903:Drug Monitoring
keywords: COPD; MARS; MRA; adherence; inhalation medication