Antihypertensive treatment and blood pressure trends among South African adults: A repeated cross-sectional analysis of a population panel survey

BackgroundRecent findings suggest a decline in mean blood pressure and prevalence of uncontrolled hypertension in the South African adult population in the last decade, in contrast with the increase previously observed. This study aimed at quantifying the contribution of antihypertensive treatment to this decline.MethodsWe used data from the four waves of the National Income Dynamics Study between 2008 and 2015 and analysed changes in systolic (SBP) and diastolic blood pressure (DBP) and prevalence of uncontrolled hypertension among South African adults (15 years and above). We compared the observed changes with a counterfactual scenario in which the impact of antihypertensive treatment was estimated by censored regression and removed, with and without adjustment for BMI, waist circumference, alcohol use and smoking.ResultsDuring the study period, the prevalence of antihypertensive treatment rose from 13.1% to 17.6% among women and from 5.3% to 8.2% among men. Concurrently–despite worsening trends in major biobehavioural risk factors for elevated blood pressure–mean SBP decreased in both genders, DBP decreased among women and was stable among men. The odds of uncontrolled hypertension decreased by 4%/year among women and 1%/year among men. After removing the treatment effect, the downward trend in the odds of uncontrolled hypertension was reduced to 1%/year among women and completely offset among men. Among those 55 years and older, but not among younger subjects, treatment effects also explained most of the observed decreases in mean SBP and DBP.ConclusionsAmong South African adults, we infer that diffusion of antihypertensive treatment contributed substantially to the downward trend in the prevalence of uncontrolled hypertension observed between 2008 and 2015. The marked decrease in SBP and uncontrolled hypertension found among younger participants could not be explained by treatment nor by the changing distribution of the measured risk factors available in this study, and requires further investigation.

研究背景 近期研究表明，近十年来南非成年人群的平均血压与未控制高血压患病率均出现下降，与此前观测到的上升趋势形成鲜明反差。本研究旨在量化降压治疗对这一下降趋势的贡献。
研究方法 本研究采用2008至2015年间全国收入动态追踪研究（National Income Dynamics Study）的四轮调查数据，对南非15岁及以上成年人群的收缩压（systolic blood pressure, SBP）、舒张压（diastolic blood pressure, DBP）及未控制高血压患病率的变化展开分析。我们将观测到的变化与两类反事实情景进行对比：通过删失回归（censored regression）估算降压治疗的影响并予以移除，其中一组调整了体质指数（BMI，Body Mass Index）、腰围、饮酒与吸烟行为，另一组未进行上述调整。
研究结果 研究周期内，女性的降压治疗覆盖率从13.1%升至17.6%，男性则从5.3%升至8.2%。与此同时，尽管血压升高的主要生物行为风险因素呈现恶化趋势，但两性的平均收缩压均有所下降；女性平均舒张压出现下降，男性则维持稳定。女性未控制高血压的患病优势比每年降低4%，男性每年降低1%。在移除治疗影响后，女性未控制高血压患病优势比的下降趋势放缓至每年1%，而男性的下降趋势则完全被抵消。在55岁及以上人群（而非年轻群体）中，降压治疗的影响同样解释了平均收缩压与舒张压观测到的大部分降幅。
研究结论 我们推断，2008至2015年间，降压治疗的普及大幅推动了南非成年人群未控制高血压患病率的下降趋势。年轻参与者中观测到的收缩压与未控制高血压的显著下降，既无法通过降压治疗解释，也无法通过本研究纳入的可测量风险因素的分布变化来阐释，该现象有待进一步研究。