Visit-to-visit variability of blood pressure and cardiovascular disease and all-cause mortality: a systematic review and meta-analysis.

Visit-to-visit variability of blood pressure (BP) has been associated with cardiovascular disease (CVD) and mortality in some but not all studies. We conducted a systematic review and meta-analysis to examine the association between visit-to-visit variability of BP and CVD and all-cause mortality. Medical databases were searched through June 4, 2014, for studies meeting the following eligibility criteria: adult participants; BP measurements at ≥3 visits; follow-up for CVD, coronary heart disease, stroke, or mortality outcomes; events confirmed via database, death certificate, or event ascertainment committee; and adjustment for confounders. Data were extracted by 2 reviewers and pooled using a random-effects model. Overall, 8870 abstracts were identified of which 37 studies, representing 41 separate cohorts, met inclusion criteria. Across studies, visit-to-visit variability of systolic BP and diastolic BP showed significant associations with outcomes in 181 of 312 (58.0%) and 61 of 188 (32.4%) analyses, respectively. Few studies provided sufficient data for pooling risk estimates. For each 5 mm Hg higher SD of systolic BP, the pooled hazard ratio for stroke across 7 cohorts was 1.17 (95% confidence interval [CI], 1.07-1.28), for coronary heart disease across 4 cohorts was 1.27 (95% CI, 1.07-1.51), for CVD across 5 cohorts was 1.12 (95% CI, 0.98-1.28), for CVD mortality across 5 cohorts was 1.22 (95% CI, 1.09-1.35), and for all-cause mortality across 4 cohorts was 1.20 (95% CI, 1.05-1.36). In summary, modest associations between visit-to-visit variability of BP and CVD and all-cause mortality are present in published studies. However, these findings are limited by the small amount of data available for meta-analysis.