[OP.LB.02.08] THE EFFECT OF BLOOD PRESSURE LOWERING ON MORTALITY AND CARDIOVASCULAR DISEASE IS MODIFIED BY BASELINE SYSTOLIC BLOOD PRESSURE: SYSTEMATIC REVIEW & META-ANALYSIS.

OBJECTIVE: To assess the effect of blood pressure lowering treatment on the risk of death and cardiovascular disease at different blood pressure levels.

DESIGN AND METHOD: We used data from a previous systematic review and meta-analysis of blood pressure lowering treatment, adding the results from the recently published HOPE-3 trial. The previous review standardised risk ratio and study weights according to blood pressure lowering, which has previously been associated with deranged results. We re-analysed data using non-standardised methods and explored reasons for heterogeneity when present.

RESULTS: We included 60 trials, including 295 002 patients, in our meta-analyses. The relative risk reduction with blood pressure lowering was attenuated at lower baseline systolic blood pressure (p < 0.001 for mortality, major cardiovascular events, stroke and heart failure). Antihypertensive treatment reduced the risk of death only if baseline systolic blood pressure was >150 mmHg (RR 0.87, 95 % CI 0.80-0.95 if SBP 150-159 mmHg, compared to RR 1.01, 0.96-1.07 if SBP 140-149 mmHg). For major cardiovascular events a beneficial effect was seen across blood pressure strata, but the benefit was significantly smaller at lower blood pressure levels (RR 0.92, 0.87-0.98 if SBP 130-139 mmHg, compared to 0.75, 0.67-0.84 if SBP > 160 mmHg). We observed significant heterogeneity in the 130-139 and 140-149 mmHg blood pressure strata in the major cardiovascular event analysis (I2 59 %, p = 0.001 respectively I2 65 %, p = 0.005). The heterogeneity disappeared when analyses were restricted to trials without previous cardiovascular disease. In trials with a baseline systolic blood pressure <140 mmHg, treatment reduced the risk of major cardiovascular events only in patients with pre-existing disease (RR 0.84, 0.80-0.89), whereas treatment effect was neutral in primary preventive trials (RR 0.98, 0.94-1.02, p < 0.001 for interaction).

CONCLUSIONS: The effect of blood pressure lowering on mortality and cardiovascular disease is modified by baseline systolic blood pressure and pre-existing cardiovascular disease. If cardiovascular disease is present, blood pressure lowering is beneficial across all blood pressure levels. Without cardiovascular disease, however, there is no benefit with treatment < 140 mmHg.