Abstract
BACKGROUND: Recent guidelines recommended a systolic blood pressure (SBP) target of < 130 mmHg for patients with or without diabetes but without providing a lower bound. Our study aimed to explore whether additional clinical benefits remain at achieved blood pressure (BP) levels below the recommended target. METHODS: We performed a secondary analysis of the Systolic Blood Pressure Intervention Trial (SPRINT) among the non-diabetic population and the Action to Control Cardiovascular Risk in Diabetes BP (ACCORD-BP) trial among diabetic subjects. We used the propensity score method to match patients from the intensive BP group to those from the standard group in each trial. Individuals with different achieved BP levels from the intensive BP group were used as "reference." For each stratum, the trial-specific primary outcome (i.e., composite outcome of myocardial infarction (MI), acute coronary syndrome not resulting in MI, stroke, acute decompensated heart failure (HF), or cardiovascular death for SPRINT; non-fatal MI, non-fatal stroke, or cardiovascular death for ACCORD-BP) was compared by Cox regression. RESULTS: A non-linear association was observed between the mean achieved BP and incidence of composite cardiovascular events, regardless of treatment allocation. The significant treatment benefit for primary outcome remained at SBP 110-120 mmHg (hazard ratio, 0.59 [95% CI, 0.46, 0.76] for SPRINT; 0.67 [0.52, 0.88] for ACCORD-BP) and SBP 120-130 mmHg for SPRINT (0.47 [0.34, 0.63]) but not for ACCORD-BP (0.93 [0.70, 1.23]). The results were similar for the secondary outcomes including all-cause mortality, cardiovascular mortality, MI, stroke, and HF. Intensive BP treatment benefits existed among patients maintaining a diastolic BP of 60-70 mmHg but were less distinct. CONCLUSIONS: The treatment benefit persists at as low as SBP 110-120 mmHg irrespective of diabetes status. Achieved very low BP levels appeared to increase cardiovascular events and all-cause mortality.