Association between high blood pressure and long term cardiovascular events in young adults: systematic review and meta-analysis

Abstract

Objective: To evaluate and quantify the future risk of cardiovascular events in young adults with high blood pressure.

Design: Systematic review and meta-analysis.

Data sources: Medline, Embase, and Web of Science were searched from inception to 6 March 2020. Relative risks were pooled using a random effects model and expressed with 95% confidence intervals. Absolute risk difference was calculated. Dose-response relations between blood pressure and individual outcomes were assessed by a restricted cubic spline model.

Eligibility criteria for selecting studies: Studies were selected that investigated the adverse outcomes of adults aged 18-45 with raised blood pressure. The primary study outcome was a composite of total cardiovascular events. Coronary heart disease, stroke, and all cause mortality were examined as secondary outcomes.

Results: Seventeen observational cohorts consisting of approximately 4.5 million young adults were included in the analysis. The average follow-up was 14.7 years. Young adults with normal blood pressure had increased risk of cardiovascular events compared with those with optimal blood pressure (relative risk 1.19, 95% confidence interval 1.08 to 1.31; risk difference 0.37, 95% confidence interval 0.16 to 0.61 per 1000 person years). A graded, progressive association was found between blood pressure categories and increased risk of cardiovascular events (high normal blood pressure: relative risk 1.35, 95% confidence interval 1.22 to 1.49; risk difference 0.69, 95% confidence interval 0.43 to 0.97 per 1000 person years; grade 1 hypertension: 1.92, 1.68 to 2.19; 1.81, 1.34 to 2.34; grade 2 hypertension: 3.15, 2.31 to 4.29; 4.24, 2.58 to 6.48). Similar results were observed for coronary heart disease and stroke. Generally, the population attributable fraction for cardiovascular events associated with raised blood pressure was 23.8% (95% confidence interval 17.9% to 28.8%). The number needed to treat for one year to prevent one cardiovascular event was estimated at 2672 (95% confidence interval 1639 to 6250) for participants with normal blood pressure, 1450 (1031 to 2326) for those with high normal blood pressure, 552 (427 to 746) for those with grade 1 hypertension, and 236 (154 to 388) for those with grade 2 hypertension.

Conclusions: Young adults with raised blood pressure might have a slightly increased risk of cardiovascular events in later life. Because the evidence for blood pressure lowering is limited, active interventions should be cautious and warrant further investigation.

Fig 1

Flowchart of selection of studies included in meta-analysis

Fig 2

Forest plot of relative risks of cardiovascular events across blood pressure categories compared with optimal blood pressure. RR=relative risk

Fig 3

Forest plot of relative risks of coronary heart disease across blood pressure categories compared with optimal blood pressure. RR=relative risk

Fig 4

Forest plot of relative risks of stroke across blood pressure categories compared with optimal blood pressure. RR=relative risk

Fig 5

Forest plot of relative risks of all cause mortality across blood pressure categories compared with optimal blood pressure. RR=relative risk

Fig 6

Population attributable fraction and number needed to treat for one year for different study outcomes across blood pressure categories. NNT=number needed to treat

Fig 7

Nonlinear dose-response analysis of systolic blood pressure (top panel) and diastolic blood pressure (bottom panel) and risk of cardiovascular events, coronary heart disease, stroke, and all cause mortality. Shaded areas indicate 95% confidence intervals for corresponding coloured lines