Red cell distribution width as a cardiovascular risk predictor in adults with hypertension in sub-Saharan Africa

Red cell distribution width (RDW) quantifies the degree of variation in erythrocyte size, is identified as a potential marker of adverse cardiovascular events, and may be a surrogate marker for assessing cardiovascular disease (CVD) risk in low-resource settings. We evaluated RDW as a predictor of CVD risk compared to the World Health Organization (WHO) CVD risk score among adults with hypertension attending primary healthcare centers (PHCs) in Ghana and Nigeria. Adults with hypertension attending selected PHCs in Ghana and Nigeria participated in a cross-sectional study. Each participant underwent blood pressure (BP) measurement and laboratory evaluation (RDW, total cholesterol, and fasting blood sugar) following standard methods. We recruited 319 adults aged 40-74 years from the study sites. The mean (standard deviation) RDW was 13.96 (1.1%). The median CVD risk score was 8.11% [interquartile range (IQR) 4.00 to 11.00]. For participants with hemoglobin (Hb) levels ≥ 12 g/dL, RDW showed positive correlations with age (r = 0.136; p = 0.042); systolic BP (r = 0.183; p = 0.006), diastolic BP (r = 0.206, p = 0.002) and WHO CVD risk scores (r = 0.166, p = 0.013). Multiple linear regression showed an independent association between RDW and WHO CVD risk scores with an upward gradient, and was most significant at 3rd quartiles. Using receiver operating characteristic curve, the C-statistic was 0.673 (95% confidence interval: 0.618 to 0.724), p = 0.031. With a cut-off of >14, the RDW demonstrated a sensitivity of 81.82% and specificity of 55.84%. This study shows that at Hb levels ≥ 12 g/dL, RDW modestly predicted CVD risk in adults with hypertension in sub-Saharan Africa.