Aims: This study aimed to establish the psychometric properties of a questionnaire measure of patients' adherence to medications to elicit patients' report of medication use in a variety of clinical samples. The reliability and validity were assessed in patients with hypertension. Additional analyses were performed on other patient groups.Methods: Using a cross‐sectional study design, a 10‐item version of the Medication Adherence Report Scale (©Professor Rob Horne) was piloted in two samples of patients receiving treatment for hypertension (n = 50 + 178), asthma (n = 100) or diabetes (n = 100) at hospital outpatient or community clinics in London and the south‐east of England. Following principal components analysis, five items were retained to form MARS‐5 (©Professor Rob Horne). Evaluation comprised internal reliability, test‐retest reliability, criterion‐related validity (relationship with blood pressure control) and construct validity (relationship with patients' beliefs about medicines).Results: The MARS‐5 demonstrated acceptable reliability (internal and test‐retest) and validity (criterion‐related and construct validity) in these patient groups. Internal reliability (Cronbach's α) ranged from 0.67 to 0.89 across all patient groups; test‐retest reliability (Pearson's r) was 0.97 in hypertension. Criterion‐related validity was established with more adherent hypertension patients showing better blood‐pressure control (χ² = 4.24, df = 1, P < .05). Construct validity with beliefs about medicines was demonstrated with higher adherence associated with stronger beliefs in treatment necessity and lower treatment concerns.Conclusions: The MARS‐5 performed well on several psychometric indicators in this study. It shows promise as an effective self‐report tool for measuring patients' reports of their medication use across a range of health conditions.

Pharmaceutical prescriptions are core to the treatment of most chronic illnesses, yet only half are taken as prescribed. Despite the high costs of nonadherence to individuals and society, effective adherence-promoting interventions are elusive. This is partly due to the sheer complicity of the issue. There are numerous determinants of adherence, both internal to the patient (intrinsic) and external (extrinsic, e.g., environmental or health system-related factors). Also, the relative importance of these determinants varies between individuals and even within the same individual over time and across treatments, presenting a challenge for intervention design. One complication is that interventions can target several levels: (1) patient (e.g., enhancing motivation and/or ability to adhere), (2) patient-provider interactions (e.g., improving communication and the prescribing process), and (3) the healthcare system (e.g., providing the opportunity to access medication through regulatory approval and co-payment schemes). Here, we focus on level 1: the patient. Although environmental factors are important, the effect of an intervention designed to change them will depend on how they impact on the individual. We describe the Perceptions and Practicalities Approach (PAPA), a pragmatic framework positing that adherence/nonadherence is essentially a produce of individual motivation and ability. Adherence interventions, targeted at any level, will therefore be more effective if tailored to address the perceptions and practicalities underpinning individual motivation and ability. We discuss how PAPA can be operationalized, including the application of theoretical models of illness and treatment representation (Necessity-Concerns Framework and Leventhal’s Common-Sense Model) to address salient adherence-related perceptions.