It is not clear whether controlling blood pressure (BP) through antihypertensive treatment can eliminate the attributable risk of cardiovascular disease (CVD). We aimed to evaluate the residual risk of CVD in treated individuals with hypertension.
We used the data from the Isfahan Cohort Study, a population-based prospective study of Iranian adults aged 35 years or older at baseline. Of a total 6504, 5432 participants free of a CVD history at baseline with at least one follow-up were included. Participants were stratified to five different BP categories based on baseline BP (cutoffs of systolic/diastolic BP at 120/80 and 140/90 mmHg) and treatment status (yes/no). Cox proportional hazard regression was used to predict the hazard ratio (HR) for CVD events and its corresponding 95% confidence interval (CI).
During a median 10.9 years and 49,439 person-years of follow-up, a total of 706 incident CVD events were recorded comprising 563 cases of coronary heart disease (CHD) and 143 stroke. Successfully treated individuals were at higher risk of CVD (HR 1.93, 95% CI 1.28–2.90) and CVD mortality (HR 2.64, 95% CI 1.29–5.40) than the group with optimal BP in a multivariable model. Further adjusting for treatment duration and BP attenuated but did not eliminate the CVD (HR 1.65, 95% CI 1.08–2.52) and CVD mortality (HR 2.17, 95% CI 1.03–4.57) risk. A stronger association was found for CHD (HR 2.58, 95% CI 1.66–4.02) but not for stroke (HR 0.46, 95% CI 0.14–1.56). Both men (HR 2.45, 95% CI 1.27–4.74) and women (HR 1.62, 95% CI 0.95–2.77) with controlled BP had a higher risk of cardiovascular events, although not significant in women. In untreated individuals, the risk of CVD started at 120/80 mmHg (HR 1.38, 95% CI 1.09–1.75) and escalated in individuals with values from 130/85 mmHg to less than 140/90 mmHg (HR 1.94, 95% CI 1.29–2.92).
A substantial residual risk of CHD remains despite treatment which could not be explained by usual confounders and BP itself. Hence, despite undeniable benefits of lowering BP, treatment may not totally counterbalance the risk of CVD at the population level.
1Isfahan Cardiovascular Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
2Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore
3Department of Public Health and Epidemiology, Institute of Applied Health Research, University of Birmingham, Birmingham, United Kingdom
4Cardiac Rehabilitation Research Center, Cardiovascular Research Institute, Isfahan University of Medical Sciences, Isfahan, Iran
5Alzheimer's Disease Center, Rush University Medical Center, Chicago, CHICAGO, IL, USA
6School of Population and Public Health, University of British Columbia, Vancouver, Canada