http://orcid.org/0000-0003-4848-6807
Forbes et al.Citation1 evaluated self-reported medication adherence scales in their review and concluded that combining various methods for evaluating patient medication adherence may be appropriate. It was reported that no scale could be considered as a gold standard when measuring patient medication adherenceCitation2. Several self-reported scales, namely the Shea scaleCitation3, Brief Medication Questionnaire (BMQ)Citation4, Adherence to Refills and Medications Scale (ARMS)Citation5, and the 4- and 8-item Morisky’s Medication Adherence Scale (MMAS) were evaluated in the reviewCitation2,Citation3,Citation6,Citation7. The authors accurately pointed out the limitations of these scales, such as inaccuracy, over-estimation of adherence, complexity of scale, and the cost associated with the license agreement of MMAS.
We developed a new scale, known as the General Medication Adherence Scale (GMAS). It was conceived and designed as a collaborative project of academicians from developing countries such as Pakistan and MalaysiaCitation8,Citation9. The GMAS was validated in a Pakistani population and was translated into English, followed by its validation. The need to design GMAS rose from the same set of limitations and weaknesses of the self-reported scales as identified by Forbes et al.Citation1.
Notwithstanding ease of administration of the Shea Scale compared with MMAS and BMQ, it did not measure patient behavior resulted non-adherence. The MMAS was useful in measuring polypharmacy related non-adherence; however, MMAS and BMQ were too complexCitation4. These scales had limitations, i.e. a yes/no response that did not differentiate between highly adherent and partially adherent patients for a given scenario, and designated varying adherence levels based on cumulative score obtained after answering all questions. Additionally, MMAS had a cost of licensureCitation10.
Cost-related non-adherence in patients has been reported as a determinant to adhering pharmacotherapy, especially in developing countries where patients mostly pay out-of-pocket medical costsCitation11–13. Hence, the findings of Forbes et al.Citation1 reiterate our apprehensions. Besides, the MMAS, BMQ, Shea Scale, as well as ARMS are not even suitable for patients for whom out-of-pocket medical expenditures is a barrier to adherence, let alone being a gold standardCitation2,Citation14.
The GMAS was designed keeping these shortcomings in mind. It includes 11 multiple choice questions with four possible answers, i.e. always, mostly, sometimes, and never. It measured adherence across three domains, namely patient behaviour, comorbidity and pill burden, and out-of-pocket expenditure. It demonstrated a better internal consistency (0.84) for the Urdu version that focused on low literacy patients as well as for the English version that targeted literate patients. The internal consistency was better than the former scales, and a high response rate (91%) was achieved. Moreover, GMAS was sensitive (>74%) while screening patients with low adherence due to polypharmacy and out-of-pocket expenditure. Besides, it demonstrated high sensitivity (>75%) while screening patients with partial-to-no adherence based on their educational level. These results were better than those reported by the Shea Scale, and equally effective as those demonstrated by ARMS for patients with low literacyCitation3,Citation5. Further results relating to clinical outcomes are awaitedCitation15.
Extensive reviews such as the one by Forbes et al.Citation1 are helpful to appraise the strengths and limitations of available adherence measuring tools. They create a niche to encourage further research towards devising ways to overcome existing inadequacies and addressing shortcomings that are a barrier to applicability of such scales in developing countries.
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Declaration of funding
The authors declare that no funding was sought for the publication of this work.
Declaration of financial/other relationships
AAN and MAH declare that they have no financial/other relationship with any commercial entity regarding this publication. CMRO peer reviewers on this manuscript have no relevant financial or other relationships to disclose.
Acknowledgements
None.
References
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