Assessing adherence to medications: Is there a differencbetween a subjective method and an objective method, between using them concurrently?

Abstract

Background: Patients’ adherence to medication can be assessed by several subjective or objective methods. The Global Initiative for Asthma (GINA) harecommended the use of both measures simultaneously. Objective: To assess patients’ adherence to medication using a subjective or an objective methoseparately, and via using a combination of both methods. As well as identifying the degree of agreement between the two methods. Methods: Participantwho met the study inclusion criteria completed the Adherence to Asthma Medication Questionnaire (AAMQ). A retrospective audit was conducted in ordeto extract pharmacy refill records for the previous twelve months. The patients’ pharmacy refill records were expressed using the Medication PossessioRatio (MPR). Data were analyzed using the Statistical Package for Social Science. The degree of agreement was determined by Cohen’s kappa coefficien(κ). Results: In terms of the difference in the ability of each method to identify non-adherent patients, a higher percentage of non-adherent patientwere identified using the self-reported AAMQ (61.4%) compared to the pharmacy refill records (34.3%). When both methods, in combination, were useto assess adherence, the percentage of non-adherent patients was 80.0%, which is higher than each method when used separately. Twenty percent othe patients were considered adherent on both assessment methods, while 15.7% were considered non-adherent via both methods. Consequentlthe AAMQ and pharmacy refill records agreed on 35.7% of the patients. The degree of agreement analysis showed a low correlation between the twmethods. Conclusion: The combination strategy resulted in a higher percentage of non-adherent patients, compared to using a subjective (the AAMQ) oan objective (the pharmacy refill records) method. The GINA guideline proposition may be supported by the present study’s findings.