Medication Adherence, Complementary Medicine Usage and Progression of Diabetic Chronic Kidney Disease in Thais

Non-adherence to medication is receiving more attention as a significant problem common to management of chronic diseases including diabetes and chronic kidney disease (CKD). This study was designed to assess the medication adherence and self-medication in a cohort of Thai patients with diabetic kidney disease, and its association with clinical outcomes.

Non-dialysis patients with diabetic CKD visiting outpatient's clinics of Siriraj Hospital, the largest tertiary care in Thailand, were asked for participation. Self-administered questionnaire was given to assess medication adherence (the 6-item-medication-taking-behavior measure in Thai), complementary medicine usage, and personal information. Clinical, pharmaceutical, and relevant laboratory data (at current and the last visit of around 12 months) were abstracted from the medical records.

Of the 220 participants eligible (54.1% male, mean age 71.3), 50.9%, 24.1%, and 25% were classified as high-, medium-, and low-medication adherence, respectively. Overall, 24.1% reported self-usage of at least one type of herbal or complementary medicines. The most commonly identified items were cordyceps, cod liver oil, Nan Fui Chao, and turmeric (6 each), with unidentified Thai herbal mixture in 11. On multivariate analysis, late-stage CKD (stage IV-V) was the only independent predictor for low adherence (odds ratio (OR), 5.54; 95% confidence interval (CI), 2.82-10.88). Low adherence was associated with higher blood pressure, lower estimated glomerular filtrate rate (eGFR), and more eGFR decline with greater risk of being rapid CKD progressor (annual eGFR drop >5 mL/min/1.73 m²) [OR, 1.15; 95% CI, 1.06-1.25].

Medication taking behavior was a frequently encountered problem in Thai diabetic CKD patients. Increased medication non-adherence was independently predicted by stages of increasing CKD severity, and it was associated with poorer hypertensive control and kidney outcome. Targeting interventions to improve medication adherence should be an important strategy to slow CKD progression among patients with diabetic CKD.