The Blood Pressure Lowering Treatment Trialists' Collaboration meta-analysis - pharmacological blood pressure lowering for prevention of cardiovascular disease

The Blood Pressure Lowering Treatment Trialists' Collaboration undertook a meta-analysis of individual participant-level data from 48 randomised trials of pharmacological blood pressure lowering

• trials involved medications versus placebo or other classes of blood pressure-lowering medications, or between more versus less intensive treatment regimens, which had at least 1000 persons-years of follow-up in each group
• the data was pooled to investigate the stratified effects of blood pressure-lowering treatment in participants with and without prevalent cardiovascular disease (ie, any reports of stroke, myocardial infarction, or ischaemic heart disease before randomisation), overall and across seven systolic blood pressure categories (ranging from <120 to >= 170 mm Hg)
• primary outcome was a major cardiovascular event (defined as a composite of fatal and non-fatal stroke, fatal or non-fatal myocardial infarction or ischaemic heart disease, or heart failure causing death or requiring admission to hospital), analysed as per intention to treat
  
  
• data for 344716 participants from 48 randomised clinical trials were available for this analysis
  
  
• pre-randomisation mean systolic/diastolic blood pressures were:
  • 146/84 mm Hg in participants with previous cardiovascular disease (n=157728)
  • 157/89 mm Hg in participants without previous cardiovascular disease (n=186988)
    
    
• was substantial spread in participants' blood pressure at baseline, with 31239 (19.8%) of participants with previous cardiovascular disease and 14928 (8.0%) of individuals without previous cardiovascular disease having a systolic blood pressure of less than 130 mm Hg
  

Study Results:

• relative effects of blood pressure-lowering treatment were proportional to the intensity of systolic blood pressure reduction
• after a median 4.15 years' follow-up, 42324 participants (12.3%) had at least one major cardiovascular event
  • if without previous cardiovascular disease at baseline
    • incidence rate for developing a major cardiovascular event per 1000 person-years was 31.9 (95% CI 31.3-32.5) in the comparator group and 25.9 (25.4-26.4) in the intervention group
  • if previous cardiovascular disease at baseline
    • incidence rate for developing a major cardiovascular event per 1000 person-years rates were 39.7 (95% CI 39.0-40.5) and 36.0 (95% CI 35.3-36.7), in the comparator and intervention groups, respectively
• hazard ratios (HR) associated with a reduction of systolic blood pressure by 5 mm Hg for a major cardiovascular event
  • in participants without previous cardiovascular disease was 0.91, 95% CI 0.89-0.94
  • in partipants with previous cardiovascular disease was 0.89, 95% CI 0.86-0.92
    
    
• a 5 mm Hg reduction of systolic blood pressure reduced the risk of major cardiovascular events (defined as a composite of fatal and non-fatal stroke, fatal or non-fatal myocardial infarction or ischaemic heart disease, or heart failure causing death or requiring admission to hospital) by about 10%, irrespective of previous diagnoses of cardiovascular disease, and even at normal or high-normal blood pressure values over the median 4.15 year period. The reduction of risk of the individual components of the primary end-point by a 5mm Hg reduction in systolic blood pressure were:
  • risk for stroke was reduced by 13%
  • risk for heart failure was reduced by 13%
  • risk for ischaemic heart disease was reduced by 8%
  • risk for death from cardiovascular disease was reduced by 5%
    
    
• findings suggest that a fixed degree of pharmacological blood pressure lowering is similarly effective for primary and secondary prevention of major cardiovascular disease, even at blood pressure levels currently not considered for treatment
  • relative risk reductions were proportional to the intensity of blood pressure-lowering
  • neither the presence of cardiovascular disease or the level of blood pressure at study entry modified the effect of treatment
  • the study authors suggest that "On the basis of this study, the decision to prescribe blood pressure medication should not be based simply on a
    previous diagnosis of cardiovascular disease or an individual's current blood pressure. Rather, blood pressure medication should be viewed as an effective tool for preventing cardiovascular disease when an individual's cardiovascular risk is elevated.."

Reference:

• 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: an individual participant-level data meta-analysis. Lancet 2021; 397: 1625-36.