Blood pressure-lowering treatment strategies based on cardiovascular risk versus blood pressure: A meta-analysis of individual participant data

Abstract

Background: Clinical practice guidelines have traditionally recommended blood pressure treatment based primarily on blood pressure thresholds. In contrast, using predicted cardiovascular risk has been advocated as a more effective strategy to guide treatment decisions for cardiovascular disease (CVD) prevention. We aimed to compare outcomes from a blood pressure-lowering treatment strategy based on predicted cardiovascular risk with one based on systolic blood pressure (SBP) level.

Methods and findings: We used individual participant data from the Blood Pressure Lowering Treatment Trialists' Collaboration (BPLTTC) from 1995 to 2013. Trials randomly assigned participants to either blood pressure-lowering drugs versus placebo or more intensive versus less intensive blood pressure-lowering regimens. We estimated 5-y risk of CVD events using a multivariable Weibull model previously developed in this dataset. We compared the two strategies at specific SBP thresholds and across the spectrum of risk and blood pressure levels studied in BPLTTC trials. The primary outcome was number of CVD events avoided per persons treated. We included data from 11 trials (47,872 participants). During a median of 4.0 y of follow-up, 3,566 participants (7.5%) experienced a major cardiovascular event. Areas under the curve comparing the two treatment strategies throughout the range of possible thresholds for CVD risk and SBP demonstrated that, on average, a greater number of CVD events would be avoided for a given number of persons treated with the CVD risk strategy compared with the SBP strategy (area under the curve 0.71 [95% confidence interval (CI) 0.70-0.72] for the CVD risk strategy versus 0.54 [95% CI 0.53-0.55] for the SBP strategy). Compared with treating everyone with SBP ≥ 150 mmHg, a CVD risk strategy would require treatment of 29% (95% CI 26%-31%) fewer persons to prevent the same number of events or would prevent 16% (95% CI 14%-18%) more events for the same number of persons treated. Compared with treating everyone with SBP ≥ 140 mmHg, a CVD risk strategy would require treatment of 3.8% (95% CI 12.5% fewer to 7.2% more) fewer persons to prevent the same number of events or would prevent 3.1% (95% CI 1.5%-5.0%) more events for the same number of persons treated, although the former estimate was not statistically significant. In subgroup analyses, the CVD risk strategy did not appear to be more beneficial than the SBP strategy in patients with diabetes mellitus or established CVD.

Conclusions: A blood pressure-lowering treatment strategy based on predicted cardiovascular risk is more effective than one based on blood pressure levels alone across a range of thresholds. These results support using cardiovascular risk assessment to guide blood pressure treatment decision-making in moderate- to high-risk individuals, particularly for primary prevention.

Fig 1. Effects of CVD risk and SBP treatment strategies on absolute number of cardiovascular events prevented over 5 y.

Expected cardiovascular events avoided over 5 y of treatment as a function of number of persons and proportion of sample treated using a CVD risk strategy (in green) and an SBP strategy (in red). Numbers associated with each curve represent the specific CVD risk level (percentage 5-y CVD risk) or SBP (mmHg) at the treatment threshold. Areas under the curve are expressed as the ratio of the obtained area to the maximum possible area (maximum number of cardiovascular events avoided multiplied by the maximum number of participants treated) with bias-corrected 95% bootstrap CIs from 10,000 repetitions in parentheses. Larger areas represent more events avoided per persons treated. CI, confidence interval, CVD, cardiovascular disease; SBP, systolic blood pressure.

Fig 2. Numbers needed to treat for 5 y to avoid 1 cardiovascular event according to CVD risk and SBP treatment strategies.

Numbers needed to treat for 5 y to avoid 1 cardiovascular event as a function of number of persons and proportion of sample treated using a CVD risk strategy (in green) and an SBP strategy (in red). Numbers associated with each curve represent the specific CVD risk level (percentage 5-y CVD risk) or SBP (mmHg) at the treatment threshold. CVD, cardiovascular disease; SBP, systolic blood pressure.

Fig 3. Performance of CVD risk and SBP treatment strategies in subgroups defined at baseline.

Estimates represent differences in areas under the curve between CVD risk and SBP treatment strategies for the number of cardiovascular events avoided per persons treated in each subgroup, defined at baseline. Bias-corrected 95% bootstrap CIs from 10,000 repetitions in parentheses. Heterogeneity for the dataset determined for meta-analyses of two complementary strata at a time was assessed using I² and corresponding 95% CIs. BP, blood pressure; CI, confidence interval, CVD, cardiovascular disease; SBP, systolic blood pressure.

Fig 4. Achieved SBP reduction according to CVD risk and SBP treatment strategies.

Achieved SBP reduction as a function of number of persons and proportion of sample treated using a CVD risk strategy (in green) and an SBP strategy (in red). Numbers associated with each curve represent the specific CVD risk level (percentage 5-y CVD risk) or SBP (mmHg) at the treatment threshold. CVD, cardiovascular disease; SBP, systolic blood pressure.

Fig 5. Relative risk reductions by blood pressure-lowering treatment, according to CVD risk and SBP treatment strategies.

Hazard ratios of major cardiovascular events by blood pressure-lowering treatment, as a function of number of persons and proportion of sample treated using a CVD risk strategy (in green) and an SBP strategy (in red). Numbers associated with each curve represent the specific CVD risk level (percentage 5-y CVD risk) or SBP (mmHg) at the treatment threshold. Hazard ratios determined from persons above each treatment threshold. CVD, cardiovascular disease; SBP, systolic blood pressure.