Despite the importance of accurate assessments in people taking medication, an overview of research on measurement properties of medication adherence assessments in adults at risk with metabolic syndrome (MS) is lacking. The purpose of this study was to present a systematic review (SR) of available published studies that evaluated measurement properties of generic self-reported instruments assessing medication adherence in adults at risk with MS.Design and method:
We searched PubMed, EMBASE, PsycINFO, and CINAHL in January, 2015. The methodological quality of studies reporting on each questionnaire was assessed using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist: reliability, validity, responsiveness, and interpretability.Results:
Of 44 relevant studies reviewed, this SR identified 32 studies using Classical Test Theory and 14 self-reported medication adherence instruments (e.g., ASK, Hill-Bone scale, MMAS, SEAMS). More than half of the studies included patients with hypertension (59.4%), then diabetes (37.5%), dyslipidemia (15.6%), and increased BMI (3.1%). Among the measurement properties, internal consistency (87.5%), hypothesis testing (81.3%), and structural validity (75.0%) were frequently assessed items, whereas there was only one study that evaluated responsiveness, and none evaluated measurement error. The Morisky Medication Adherence Scale (MMAS) (43.8%) and Hill-Bone scale (15.6%) were the most frequently used instruments and were found to be well validated with strong evidence for internal consistency, reliability, structural validity, hypothesis testing, and criterion validity.Conclusions:
MMAS-8 and Hill-Bone scale seem to be well-validated instruments to assess medication adherence in adults at risk with MS including hypertension. The findings may assist with selection of the appropriate instruments to assess medication adherence in this population. However, further studies might be needed for concept definition to better understand dimensions in each medication adherence instrument (i.e., knowledge, motivation, behaviors, and barriers). *This research was support by National Research Foundation of Korea funded by the Ministry of Education (2013R1A1A2059806).