Determinants of target organ damage in black hypertensive patients attending primary health care services in Cape Town: The Hi-Hi study

BACKGROUND In South Africa (SA) cardiovascular disease (CVD) is the second leading cause of death, with hypertension (HTN) being the predominant contributor to morbidity and mortality associated with this disease. We examined the prevalence and determinants of target organ damage (TOD) among urban black hypertensive South Africans attending primary health-care (PHC) services in Cape Town. METHODS Patients on HTN treatment, 35-65 years of age, participated in this cross-sectional study. Data relating to sociodemographic factors, medical history, lifestyle patterns, and HTN care regimens were obtained. Blood and urine samples were analyzed and electrocardiographs (ECGs) were recorded. Sokolow-Lyon and Minnesota Code (MC) criteria were used for identifying left ventricular hypertrophy (LVH). Reduced creatinine clearance (Cockroft-Gault), microalbuminuria, proteinuria, and elevated serum creatinine levels were used for identifying renal impairment by any criteria (RIC). Ischemic ECG patterns were classified in terms of MC criteria. Hypertension (HTN) is a common risk factor for cardiovascular diseases (CVDs) in adult black South Africans. More than 6 million South Africans have HTN,1,2 with rates of prevalence being 22 and 25% among urban black African men and women, respectively. Besides being a key risk factor for ischemic heart disease and stroke, undiagnosed and/or poorly controlled HTN also contributes to renal disease, left ventricular hypertrophy (LVH), other target organ damage (TOD), and premature death. In South Africa (SA) CVD is the second in the list of leading causes of death, after HIV/AIDS. Chronic diseases, which include CVD, account for 36 and 40% of deaths among men and women, respectively.(3) The high rates of undiagnosed and Multivariate logistic regression analyses were carried out to identify variables independently associated with TOD. RESULTS The study sample comprised 403 participants. RIC was identified in 26%, LVH in 35%, and ischemic ECG patterns in 49% of the participants. Uncontrolled HTN and an absence of diabetes were associated with LVH as per Sokolow-Lyon criteria. Older age, the presence of diabetes, and the use of beta-blockers were associated with RIC. Ischemic ECG patterns were associated with uncontrolled HTN, older age, male gender, the consumption of less alcohol, and higher levels of low-density lipoprotein cholesterol (LDL-C). CONCLUSIONS TOD is common in this group of black hypertensive patients attending PHC sites. Uncontrolled HTN and older age were most often associated with TOD. Reducing the burden of TOD will require improving the quality of HTN care in PHC settings.