Background: - In South Africa over 60000 deaths and 1.4 million DALYs were attributable to hypertension in 2019. Effective pharmacologic treatments for hypertension exist, and strong evidence support their efficacy in controlled situations such as those realised in clinical trials. Less is known, however, on their effectiveness in real-world situations with heterogeneous populations, less standardized treatment protocols and suboptimal adherence. Methdos: - We used harmonised data on over 100000 individuals 25 years and older from 9 nationally representative surveys conducted in South Africa between 1998 and 2017. We estimated the population prevalence of antihypertensive treatment and compared the observed distributions of blood pressure with a counterfactual scenario in which the impact of treatment was estimated by censored regression and removed. For each year, we calculated sex- and age-specific treatment effects by averaging the differences between the two distributions. Results: - Between 1998 and 2017 the prevalence of antihypertensive treatment rose from 9.6% to 22.8% among women and from 4.8% to 11.5% among men. The average reduction in systolic blood pressure among the treated (ATT) increased from 18.2 mmHg to 22.5 mmHg among women and from 15.2 mmHg to 20.8 mmHg among men. In both sexes, treatment effects increased with age, peaking at 46.7 mmHg among females and at 35 mmHg among males. Treatment effects at population level tripled during the study period, from 1.7 mmHg in 1998 to 5.3 mmHg in 2017. Similar patterns, with lower magnitude, were observed for the effects of treatment on diastolic blood pressure. Conclusions: - In the South African population, antihypertensive treatment is effective in reducing blood pressure by clinically significant amounts, resulting in a shift of the population distribution of public health relevance. Despite the still inadequate level of control achieved, it is encouraging to observe the increasing trends in the ATT, suggesting improvement in treatment protocol and adherence.
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