Health literacy, medication adherence and factors associated with blood pressure control in hypertensive patients in a primary care clinic / Shaun Paul Wayn

Background: Optimal blood pressure control is crucial to prevent cardiovascular diseases. Many factors are associated with blood pressure (BP) control. These include various sociodemographic and clinical factors, health literacy (HL), and medication adherence (MA). Poor HL and MA adversely affect BP control. However, local data is limited. This study aims to identify the predictors for blood pressure control by evaluating the association of HL, MA, and various sociodemographic and clinical factors on blood pressure control in patients with hypertension attending a primary care clinic.
Methodology: A cross-sectional study was conducted between September to December 2019 in KK Seksyen 19, Shah Alam. Convenient sampling was used to recruit 349 patients with hypertension who were ≥ 35 years old, diagnosed with hypertension for ≥ six months, and comprehend English or Malay language. Sociodemographic and clinical information was entered into a questionnaire. Health literacy was measured using the self-administered Health Literacy Survey Short-form 12-items (HLS-SF12). Medication adherence was measured using the self- administered 7-items New Medication Adherence Scale. Both tools were in English and Malay language. The HLS-SF12 and the New Medication Adherence Scale were validated in Malaysia with Cronbach alphas of 0.79 - 0.90 and 0.782, respectively.
Results: Participants’ mean age was 56.8 ± 9.6 years. The prevalence of BP control was n= 198 (56.7%) with a mean systolic and diastolic blood pressure of 135.2 ± 13.9 mmHg and 81.5 ± 9.4 mmHg, respectively. The mean HL score was 37.7 ± 4.79, ranging from 20 to 48. Most participants, n= 278 (79.6%) reported sufficient or excellent level of health literacy, and only n= 4 (1.1%) reported problematic health literacy. Univariate simple logistic regression analysis identified twelve factors which were significantly associated with blood pressure control (p< 0.25). HL (p = 0.94) was not associated with BP control. Multiple logistic regression identified four factors that were significant predictors for BP control: age, medication adherence, the number of prescribed medications and smoking. The odds of achieving BP target increased with increasing age [OR 1.05 (95% CI 1.03, 1.08), p < 0.001] and in patients with good medication adherence [OR 2.22 (95% CI 1.37-3.60), p = 0.001]. In contrast, the odds of BP control reduced with higher number of prescribed medications [OR= 0.75 (95% CI 0.65, 0.86), p < 0.001] and smoking [OR= 0.19 (95% CI 0.04, 0.96), p= 0.04].
Conclusions: Despite advances in our understanding and treatment options for hypertension, controlling blood pressure remains a challenge. It is important to identify factors influencing blood pressure control for better hypertension management and to reduce complications. In our study, health literacy was not associated with blood pressure control. Future research is recommended to further explore health literacy, and its relationship with blood pressure control to ascertain its potential importance in hypertension and other chronic diseases.