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Study Summary

The BPLTTC study examined the impact of antihypertensive therapy on individuals with normal baseline systolic blood pressure (SBP) and without a prior history of cardiovascular disease (CVD), using a one-stage individual participant data meta-analysis of 348,854 participants from 48 randomized controlled trials comparing various antihypertensive regimens. Participants averaged 65 years of age and were followed for a median of 4 years. The primary outcome was major cardiovascular events (MACE), including fatal or non-fatal stroke; fatal or non-fatal myocardial infarction; ischemic heart disease; or heart failure death or hospitalization. In the combined analysis, each 5 mmHg reduction in SBP reduced the risk of MACE by 10%; stroke, 13%; heart failure, 14%; ischemic heart disease, 7%; and cardiovascular death, 5%. In stratified analysis (see accompanying Hurst's Central Illustration), each reduction in SBP by 5 mmHg reduced the risk of MACE comparably between the primary prevention group (HR 0.91, 95% CI: 0.89, 0.94) and the secondary prevention group (HR 0.89, 95% CI: 0.86, 0.92). Risk of MACE was reduced with antihypertensive therapy regardless of baseline SBP, including for individuals with baseline SBP <120 mmHg.

Commentary

Study Strengths: This is the largest study of its kind. The analysis benefitted from the use of individual participant data, rather than the use of aggregate, published data. This approach allows for standardization across studies (e.g., inclusion and exclusion criteria, definition of variables, handling of missing values, and statistical analyses), as well as for investigation of subgroups.

Study Limitations: Further analysis is needed to understand the absolute differences in the treatment effect, which is the most relevant scale for shared decision-making. Additionally, data is needed on the prevalence and severity of side effects observed in the treatment groups, particularly among individuals with lower baseline SBP.

Next Steps/Clinical Perspectives: Current guidelines use SBP and preexisting CVD as thresholds for initiating antihypertensive therapies. This trial calls this approach into question. The BPLTTC found that neither baseline SBP nor preexisting CVD modified the effect of antihypertensive therapy on incidence of MACE. The investigators conclude that antihypertensive therapy should be considered as a risk modifier. Likewise, treatment should not be given or withheld simply on the basis of blood pressure or prior diagnosis of CVD.

The results do not imply that everyone should be on antihypertensive therapies. All participants had an indication for enrollment. Furthermore, even though the relative effects were similar across groups, those with low baseline risk would see lesser reductions in absolute risk. Indeed, in these low-risk groups, the side effects of medication may outweigh any benefit.

Additional analysis of this cohort is needed to understand the relative benefits of different antihypertensive medications on subgroups, including women, the elderly, and those with elevated diastolic blood pressure, as well as the confounding effects of individual lifestyle. Further prospective randomized trials are needed to investigate the efficacy and safety of antihypertensive medications in individuals with normal blood pressure and no prior history of CVD.

Trial References

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Rahimi K on behalf of the Blood Pressure Lowering Treatment Trialists’ Collaboration. Pharmacological blood pressure-lowering for primary and secondary prevention of cardiovascular disease across different levels of blood pressure. [Presentation at European Society of Cardiology Congress 2020, 31 August 2020]
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Reitsma  JB. Hotline session: Individual patient data meta-analysis from the Blood Pressure Lowering Treatment Trialists’ Collaboration. [Presentation at European Society of Cardiology Congress 2020, 31 August 2020]

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