Prognostic Significance of the Morning Blood Pressure Surge in Clinical Practice: A Systematic Review

BACKGROUND An exaggerated morning blood pressure surge (MBPS) may be associated with stroke and other cardiovascular events, but the threshold at which an MBPS becomes pathological is unclear. This study aimed to systematically review the existing literature and establish the most appropriate definition of pathological MBPS. METHODS A MEDLINE search strategy was adapted for a range of literature databases to identify all prospective studies relating an exaggerated MBPS to cardiovascular endpoints. Hazard ratios (HRs) were extracted and synthesized using random-effects meta-analysis. RESULTS The search strategy identified 2,964 unique articles, of which 17 were eligible for the study. Seven different definitions of MBPS were identified; the most common was a prewaking surge (mean blood pressure for 2 hours after wake-up minus mean blood pressure for 2 hours before wake-up; n = 6 studies). Summary meta-analysis gave no clear evidence that prewaking MBPS (defined by a predetermined threshold: >25-55 mm Hg) was associated with all cardiovascular events (n = 2 studies; HR = 0.94, 95% confidence interval (CI) = 0.39-2.28) or stroke (n = 2 studies; HR = 1.26, 95% CI = 0.92-1.71). However, using a continuous scale, which has more power to detect an association, there was evidence that a 10 mm Hg increase in MBPS was related to an increased risk of stroke (n = 3 studies; HR = 1.11, 95% CI = 1.03-1.20). CONCLUSIONS These findings suggest that when measured and analyzed as a continuous variable, increasing levels of MBPS may be associated with increased risk of stroke. Large, protocol-driven individual patient data analyses are needed to accurately define this relationship further.