The A14-scale: development and evaluation of a questionnaire for assessment of adherence and individual barriers

Objective To develop a questionnaire (“A14”) for the description of adherence and individual barriers as basis for adherence-enhancing interventions in the clinical and pharmaceutical setting, and to compare it to the validated German MMAS (Morisky Medication Adherence Scale). Method Fourteen questions with a 5-item likert-scale from “never” (4) to “very often” (0) were given to 150 medical inpatients. According to their score, patients were classified into non-adherent (score <50) or adherent (score 50–56). On the dichotomous MMAS, “yes” is scored 0 and “no” 1 point, a total score of 4 indicating adherence. Patients with complete scales were compared with the remaining patients regarding socio-demographic factors. Descriptive statistics, Cronbach’s Alpha, Spearman correlation, and κ were computed. Results Eighty-three participants completed both scales. Patients with missing values differed significantly regarding age, education, and adherence according to MMAS. Cronbach’s Alpha for A14 was 0.861. MMAS and A14 median total scores were 4 and 52, respectively. About 39.5% of patients were non-adherent as per MMAS compared to 40% as per A14; κ was 0.262 (P = 0.016). The total scores correlated with a Rho-value of 0.43 (P < 0.001). Conclusion The A14-scale showed good internal consistency and a significant correlation with the MMAS suggesting that it merits further investigation.