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 HbA1c 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 HbA1c, 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.