Influence of baseline systolic blood pressure on the relationship between intensive blood pressure control and cardiovascular outcomes in the Systolic Blood Pressure Intervention Trial (SPRINT).

Objective: To determine whether the effects of intensive (< 120 mmHg) compared with standard (< 140 mmHg) systolic blood pressure (SBP) treatments are different among those with different baseline SBP.

Methods: De-identified SPRINT database was used for this post hoc analysis. SPRINT participants were categorized by baseline SBP status, defined as high-SBP (≥ 140 mmHg) group versus the low-SBP (< 140 mmHg) group. The primary outcome was a composite of myocardial infarction, acute coronary syndrome not resulting in myocardial infarction, stroke, acute decompensated heart failure, or death from cardiovascular causes. Treatment-related adverse events including hypotension, syncope, and bradycardia were also evaluated. Cox regression was used to calculate hazard ratios for study outcomes with intensive compared with standard SBP treatment between these two groups.

Results: Among 9361 participants randomized (age 67.9 ± 9.4 years; 35.5% female), 4964 and 4397 had baseline low SBP (< 140 mmHg) and high SBP (≥ 140 mmHg), respectively. After a median follow-up of 3.26 years, the hazard ratio for the primary outcome was 0.65 (95% CI 0.50, 0.83) and 0.84 (95% CI 0.66, 1.06) among those in the low-SBP group and high-SBP group, respectively (P value for interaction 0.15). For treatment-related adverse events, the hazard ratio with intensive SBP treatment was 2.03 (95% CI 1.44, 2.85) for the low-SBP group and 1.80 (95% CI 1.32, 2.47) for the high-SBP group (P value for interaction 0.28).

Conclusions: Hypertensive patients with low baseline SBP may benefit from intensive SBP lowering, whereas benefits were inconclusive among those with high baseline SBP.