BACKGROUND AND PURPOSE:

• The Blood Pressure Lowering Treatment Trialists’ Collaborators (The Lancet, 2021) investigated whether the initial baseline systolic blood pressure impacts the effect of blood-pressure-lowering treatment on cardiovascular risk

METHODS:

• Meta-analysis of individual participant-level data
  • The Blood Pressure Lowering Treatment Trialists’ Collaboration
• Study inclusion criteria
  • RCTs that had at least 1000 persons-years of follow-up in each group
  • Studies that included data on pharmacological blood-pressure-lowering medications vs placebo or other classes of blood-pressure-lowering medications
  • Excluded: Trials only in setting of heart failure or short-term interventions in participants with acute myocardial infarction or other acute settings
• Exposures
  • Cardiovascular disease: Stroke | MI | Ischemic heart disease
    • Overall (all BP baselines)
    • Across seven systolic blood pressure categories (ranging from <120 to ≥170 mm Hg)
• Primary outcome
  • Major cardiovascular event analyzed as per intention to treat
  • Defined as a composite of: Fatal and non-fatal stroke | Fatal or non-fatal MI or ischaemic heart disease | Heart failure causing death or requiring admission to hospital

RESULTS:

• 48 trials | 344,716 participants
  • With previous CVD: 157,728 individuals
    • Pre-randomization blood pressure: 146/84 mm Hg
  • Without previous CVD: 186,988 individuals
    • Pre-randomization blood pressure: 157/89 mm Hg
• Systolic blood pressure of <130 mm Hg at baseline
  • With previous CVD: 19.8%
  • Without previous CVD: 8.0%
• Effects of blood-pressure-lowering treatment were proportional to the intensity of systolic blood pressure reduction
• Major CV events after median 4.15 years of follow-up: 12.3%
• Incidence rate for developing a major cardiovascular event per 1000 person-years
  • With previous cardiovascular disease at baseline
    • Comparator group: 39.7 (95% CI, 39.0 to 40.5)
    • Intervention group: 36.0 (95% CI, 35.3 to 36.7)
  • Without previous cardiovascular disease at baseline
    • Comparator group: 31.9 (95% CI, 31.3 to 32.5)
    • Intervention group: 25.9 (95% CI, 25.4 to 26.4)
• A reduction of systolic blood pressure by 5 mm Hg was associated with a reduced risk of a major CV event for participants both with and without previous CVD
  • With previous CVD: hazard ratio (HR) 0.89 (95% CI, 0.86 to 0.92)
  • Without previous CVD: HR 0.91 (95% CI, 0.89 to 0.94)
• In stratified analyses, there was no reliable evidence of heterogeneity of treatment effects on major cardiovascular events by
  • Baseline cardiovascular disease status
  • Systolic blood pressure categories

CONCLUSION:

• Reducing systolic blood pressure by 5 mm Hg reduced the risk of major cardiovascular events by about 10%, irrespective of initial systolic baseline
  • Results were not dependent on a history of cardiovascular disease
  • Same results were obtained among those with normal or high–normal blood pressure values
• Lowering blood pressure may be effective for primary and secondary prevention of major cardiovascular disease even at blood pressure levels not usually considered for treatment by current guidelines
• The authors conclude

…greater relative risk reductions are expected with larger blood pressure reductions, as is the case with multiple blood pressure lowering drugs

Thus, the feasibility of modest systolic blood pressure reductions of about 15 mm Hg across all blood pressure strata, as shown in another BPLTTC study together with the consistency of effects shown in the present study, questions the scientific validity of defining a common blood pressure target for all participants

Learn More – Primary Sources:

Pharmacological blood pressure lowering for primary and secondary prevention of cardiovascular disease across different levels of blood pressure: an individual participant-level data meta-analysis

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