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. 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.