The Mentakab hypertension study project. Part V--Drug compliance in hypertensive patients

Poor compliance with drug treatment is a barrier to effective management of hypertension. Drug compliance behaviour of 168 patients were studied, their drug compliance was measured by the pill-counting method. The prevalence of non-compliance with medication was 26%. Thirteen variables were examined for their association with compliance; these were age, sex, duration of hypertension since diagnosis, adequacy of blood pressure control, complexity of drug regimen and side-effect of drug, history of previous admission for hypertension related reason, patient's knowledge of hypertensive complications, patient's belief that drug was 'panas' or 'san', previous use of traditional treatment for hypertension, patient's fatalistic attitude, their social support and satisfaction with the health services. None of these variables were significantly related to compliance (p greater than 0.05) except adequacy of blood pressure control. The performance of patient self-report was compared with pill-count as a measure of drug compliance; it was poorly predictive of non-compliance (sensitivity = 71%, specificity = 50%). An inverse relationship was found between non-compliance with medication and patient subsequent drop-out rate. Patients who were compliant were more likely to remain on treatment and vice versa. As a measure of drug compliance, detection of drop-out compared well with pill-count (sensitivity 97%, specificity 66%, positive predictive value 89%, negative predictive value 88%).