Association Between Blood Pressure Variability and Cerebral Small-Vessel Disease: A Systematic Review and Meta-Analysis.

Background Research links blood pressure variability (BPV) with stroke; however, the association with cerebral small-vessel disease (CSVD) remains unclear. As BPV and mean blood pressure are interrelated, it remains uncertain whether BPV adds additional information to understanding cerebrovascular morphological characteristics. Methods and Results A systematic review was performed from inception until March 3, 2019. Eligibility criteria included population, adults without stroke (<4 weeks); exposure, BPV quantified by any metric over any duration; comparison, (1) low versus high or mean BPV and (2) people with versus without CSVD; and outcomes, (1) CSVD as subcortical infarct, lacunae, white matter hyperintensities, cerebral microbleeds, or enlarged perivascular spaces; and (2) standardized mean difference in BPV. A total of 27 articles were meta-analyzed, comprising 12 309 unique brain scans. A total of 31 odds ratios (ORs) were pooled, indicating that higher systolic BPV was associated with higher odds for CSVD (OR, 1.27; 95% CI, 1.14-1.42; I=85%) independent of mean systolic pressure. Likewise, higher diastolic BPV was associated with higher odds for CSVD (OR, 1.30; 95% CI, 1.14-1.48; I=53%) independent of mean diastolic pressure. There was no evidence of a pairwise interaction between systolic/diastolic and BPV/mean ORs (=0.47), nor a difference between BPV versus mean pressure ORs (=0.58). Fifty-four standardized mean differences were pooled and provided similar results for pairwise interaction (=0.38) and difference between standardized mean differences (=0.70). Conclusions On the basis of the available studies, BPV was associated with CSVD independent of mean blood pressure. However, more high-quality longitudinal data are required to elucidate whether BPV contributes unique variance to CSVD morphological characteristics.