Background: Hypertension is a major risk factor for cardiovascular morbidity and mortality. Optimum adherence to medication is still a perplexing matter for hypertensive patients in Nigeria and serum markers use as predictor for medication adherence has not been conclusive.
Aim: To define the level of antihypertensive medication adherence, its possible correlation with serum uric acid (SUA) levels and other predictors of antihypertensive medication adherence among Nigerian patients.
Methods: Patients were recruited from the University Teaching Hospital Cardiology Clinic. Blood was drawn for SUA levels. Validated 8-item MMAS-8 was administered to hypertensives to measure adherence, and correlations analysed between SUA levels and the MMAS-8 score, with SPSS-23. SUA is defined as elevated in men with concentrations of =430µmols/l, normal range 200-430µmols/l, and =360µmol/l in women, normal range140-360µmol/l. Linear regression analysis of the predictors of antihypertensive medication adherence was done. A statistical p value of <0.05 was considered significant.
Results: The total number and mean age of the cases were 271 and 60.8±12.3years respectively. MMAS-8 revealed that about half of the hypertensives (131 cases, 48.3%) had low adherence (MMAS-8 score 4), 81 cases (29.5%) had medium adherence (MMAS-8 score 2) while 59 cases (22.1%) showed high adherence (MMAS-8 score 0). Bivariate Correlation between SUA levels in hypertensives and antihypertensive medication adherence was of moderate degree and significant (r=0.396, p<0.001) suggesting that SUA levels increased with increasing non-adherence to antihypertensive medications. This correlation remained significant after adjusting for singular confounding variables like age (r=0.371 fair relationship, p=<0.001), DM (r=0.382 fair relationship, p<0.001); blood pressure (BP) duration and class r=0.356, 0.306, fair relationship p<0.001 respectively). The correlation between SUA levels and adherence to antihypertensive medications was weakened (r=0.209, p<0.001) after adjusting for combined confounding variables. Linear regression revealed that SUA levels is a predictor of antihypertensive medication adherence.
Conclusion: Antihypertensive medication adherence was unsatisfactory, elevated SUA levels correlated with low antihypertensive adherence, and this correlation was influenced by several singular and combined confounding variables in our patient population. Hence SUA levels can be a predictor and a marker of antihypertensive medication adherence.