BACKGROUND: This is the third update of the review first published in 2017. Hypertension is a prominent preventable cause of premature morbidity and mortality. People with hypertension and established cardiovascular disease are at particularly high risk, so reducing blood pressure to below standard targets may be beneficial. This strategy could reduce cardiovascular mortality and morbidity but could also increase adverse events. The optimal blood pressure target in people with hypertension and established cardiovascular disease remains unknown.
OBJECTIVES: To determine if lower blood pressure targets (systolic/diastolic 135/85 mmHg or less) are associated with reduction in mortality and morbidity compared with standard blood pressure targets (140 mmHg to 160mmHg/90 mmHg to 100 mmHg or less) in the treatment of people with hypertension and a history of cardiovascular disease (myocardial infarction, angina, stroke, peripheral vascular occlusive disease).
SEARCH METHODS: For this updated review, we used standard, extensive Cochrane search methods. The latest search date was January 2022. We applied no language restrictions.
SELECTION CRITERIA: We included randomized controlled trials (RCTs) with more than 50 participants per group that provided at least six months' follow-up. Trial reports had to present data for at least one primary outcome (total mortality, serious adverse events, total cardiovascular events, cardiovascular mortality). Eligible interventions involved lower targets for systolic/diastolic blood pressure (135/85 mmHg or less) compared with standard targets for blood pressure (140 mmHg to 160 mmHg/90 mmHg to 100 mmHg or less). Participants were adults with documented hypertension and adults receiving treatment for hypertension with a cardiovascular history for myocardial infarction, stroke, chronic peripheral vascular occlusive disease, or angina pectoris.
DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. We used GRADE to assess the certainty of the evidence.
MAIN RESULTS: We included seven RCTs that involved 9595 participants. Mean follow-up was 3.7 years (range 1.0 to 4.7 years). Six of seven RCTs provided individual participant data. None of the included studies was blinded to participants or clinicians because of the need to titrate antihypertensive drugs to reach a specific blood pressure goal. However, an independent committee blinded to group allocation assessed clinical events in all trials. Hence, we assessed all trials at high risk of performance bias and low risk of detection bias. We also considered other issues, such as early termination of studies and subgroups of participants not predefined, to downgrade the certainty of the evidence. We found there is probably little to no difference in total mortality (risk ratio (RR) 1.05, 95% confidence interval (CI) 0.91 to 1.23; 7 studies, 9595 participants; moderate-certainty evidence) or cardiovascular mortality (RR 1.03, 95% CI 0.82 to 1.29; 6 studies, 9484 participants; moderate-certainty evidence). Similarly, we found there may be little to no differences in serious adverse events (RR 1.01, 95% CI 0.94 to 1.08; 7 studies, 9595 participants; low-certainty evidence) or total cardiovascular events (including myocardial infarction, stroke, sudden death, hospitalization, or death from congestive heart failure (CHF)) (RR 0.89, 95% CI 0.80 to 1.00; 7 studies, 9595 participants; low-certainty evidence). The evidence was very uncertain about withdrawals due to adverse effects. However, studies suggest more participants may withdraw due to adverse effects in the lower target group (RR 8.16, 95% CI 2.06 to 32.28; 3 studies, 801 participants; very low-certainty evidence). Systolic and diastolic blood pressure readings were lower in the lower target group (systolic: mean difference (MD) -8.77 mmHg, 95% CI -12.82 to -4.73; 7 studies, 8657 participants; diastolic: MD -4.50 mmHg, 95% CI -6.35 to -2.65; 6 studies, 8546 participants). More drugs were needed in the lower target group (MD 0.56, 95% CI 0.16 to 0.96; 5 studies, 7910 participants), but blood pressure targets at one year were achieved more frequently in the standard target group (RR 1.20, 95% CI 1.17 to 1.23; 7 studies, 8699 participants).
AUTHORS' CONCLUSIONS: We found there is probably little to no difference in total mortality and cardiovascular mortality between people with hypertension and cardiovascular disease treated to a lower compared to a standard blood pressure target. There may also be little to no difference in serious adverse events or total cardiovascular events. This suggests that no net health benefit is derived from a lower systolic blood pressure target. We found very limited evidence on withdrawals due to adverse effects, which led to high uncertainty. At present, evidence is insufficient to justify lower blood pressure targets (135/85 mmHg or less) in people with hypertension and established cardiovascular disease. Several trials are still ongoing, which may provide an important input to this topic in the near future.
Highly valuable, high-quality evidence synthesis about an important topic pertaining to a common clinical entity.