Background and method: To determine which SBP measure best predicts cardiovascular events (CVEs) independently, a systematic review was conducted for cohorts with all patients diagnosed with hypertension, 1+ years follow-up, and coronary artery disease and stroke outcomes. Lead investigators provided ad hoc analyses for each cohort. Meta-analyses gave hazard ratios from clinic SBP (CSBP), daytime SBP (DSBP), and night-time SBP (NSBP). Coefficients of variation of SBP measured dispersion. Nine cohorts (n = 13,844) were from Europe, Brazil, and Japan. For sleep-wake SBP classification, seven cohorts used patient-specific information.
Results: Overall, NSBP's dispersion exceeded DSBP's dispersion by 22.6% with nonoverlapping confidence limits. Within all nine cohorts, dispersion for NSBP exceeded that for CSBP and DSBP. For each comparison, P = 0.004 that this occurred by chance. Considered individually, increases in NSBP, DSBP, and CSBP each predicted CVEs: hazard ratios (95% confidence intervals) = 1.25 (1.22-1.29), 1.20 (1.15-1.26), and 1.11 (1.06-1.16), respectively. However, after simultaneous adjustment for all three SBPs, hazard ratios were 1.26 (1.20-1.31), 1.01 (0.94-1.08), and 1.00 (0.95-1.05), respectively. Cohorts with baseline antihypertensive treatment and cohorts with patient-specific information for night-day BP classification gave similar results. Within most cohorts, simultaneously adjusted hazard ratios were greater for NSBP than for DSBP and CSBP: P = 0.023 and 0.012, respectively, that this occurred by chance.
Conclusion: In hypertensive patients, NSBP had greater dispersion than DSBP and CSBP in all cohorts. On simultaneous adjustment, compared with DSBP and CSBP, increased NSBP independently predicted higher CVEs in most cohorts, and, overall, NSBP independently predicted CVEs, whereas CSBP and DSBP lost their predictive ability entirely.