Barriers to achieving better drug adherence in patients with uncontrolled hypertension in primary care clinics

Abstract

Background:Poor drug adherence is one of the leading causes of uncontrolled hypertension. Little is known about the barriers to attaining good drug adherence among Chinese patients in primary care setting. Methods:Cross-sectional questionnaire survey of patients with uncontrolled hypertension was performed in five primary care clinics in Hong Kong in 2016. Patients who were given the anti-hypertensive drugs prescription, with office systolic blood pressure (SBP) > 140 mmHg &/or diastolic BP > 90 mmHg in recent 2 clinic visits were all invited. Structured questionnaire was designed to collect personal and clinical parameters. Drug adherence was assessed by validated 8-item Morisky’s Medication Adherence Scale (MMAS-8). Health literacy was assessed by Chinese Health Literacy Scale for Chronic Care (CHLSCC). Prescriptions, medical history and biochemical results were collected from electronic record system. Multi-variate logistic regression using low drug adherence as dependent variable was performed. Results:Two hundred and ninety one (291) participants were successfully recruited. The male to female ratio was 0.65. The mean age was 67.0 (S.D. 9.9). More than 80% of them reported good to moderate drug adherence while 13.7% of them had low drug adherence. More than half of them had inadequate health literacy. The mean number of years since hypertension diagnosed was 9.65 (S.D. 8.73). Almost 40% of them had hypertension less than 5 years. The most popular prescription was once-daily regimen, with 2 or more anti-hypertensive drugs. Calcium channel blocker was most commonly prescribed. In terms of the logistic regression model predicting low drug adherence, only diagnosis of HT less than 5 years was statistically significant (adjusted OR = 2.32, 95% C.I. 1.12-4.80, p = 0.02). There was no statistical significance in sex, older age, educational level, health literacy, occupation, number of types of antihypertensive drugs and daily frequency of drugs. Conclusion:In primary care setting, patients with uncontrolled hypertension reported satisfactory drug adherence. They would have lower drug adherence if their hypertension were diagnosed less than 5 years.