Conventional adherence assessment methods are low‐sensitivity diagnostic tests in people with type 2 diabetes: The TARGET study

Aims To evaluate the performance of conventional adherence assessment methods against objective chemical adherence testing (CAT) in people with type 2 diabetes. Methods In this prospective cohort study, 90 participants with type 2 diabetes attending primary care were assessed using CAT ( n = 49), medication possession ratio (MPR; n = 60) and Hill‐Bone Medication Adherence Scale (HBMAS; n = 58). Associations with HbA 1c and blood pressure (BP) were assessed, and within‐person diagnostic performance was evaluated in 21 participants with all three measures. Results Only CAT‐defined non‐adherence was associated with significantly higher HbA 1c , while CAT and MPR showed a significant association with diastolic BP. Within‐person analysis suggested poor sensitivity for both MPR (16.7%; 95% CI 4.7–44.8) and HBMAS (66.7%; 95% CI 39.1–86.2), although HBMAS demonstrated very low specificity (11.1%; 95% CI 2.0–43.5) compared with CAT. Conclusions Conventional adherence methods are low‐sensitivity diagnostic tests, and CAT offers improved diagnosis of non‐adherence in people with type 2 diabetes.