Characteristics of month-by-month blood pressure variability in patients on hemodialysis

Introduction: Poor prognosis in hemodialysis patients is due to the increased prevalence of cardiovascular diseases among them. We previously reported that higher visit-by-visit blood pressure variability is associated with increased cardiovascular mortality in hemodialysis patients. This present study aimed to investigate the characteristics of month-by-month blood pressure variability in these patients. Methods: A total of 324 maintenance hemodialysis patients, who could be followed up for 60 months, were recruited. We used standard deviation (SD), coefficient of variation (CV), and variation independent of the mean (VIM) in pre- and post-dialysis systolic blood pressure (pre- and post-SD, pre- and post-CV and pre- and post-VIM) as an index of month-by-month blood pressure variability (MMBPV). We investigated (1) the reproducibility of month-by-month blood pressure variability, (2) relationship between these values and background factors, and (3) association between these values and mortality. Results: MMBPV (pre- and post-SD, pre- and post-CV and pre- and post-VIM) showed significant reproducibility [intraclass correlation, 0.483 (P <0.001), 0.553 (P <0.001), 0.450 (P <0.001), 0.518 (P <0.001), 0.456 (P <0.001) and 0.522 (P <0.001), respectively]. High pre-VIM was associated with high interdialytic weight gain and poor nutritional status. High post-VIM was associated with glucose intolerance, high interdialytic weight gain, and poor nutritional status and associated with high rate of cardiovascular deaths independent of other factors (hazard ratio: 1.104, 95% confidence interval: 1.011-1.207, P = 0.028). Conclusion: These data suggested that pre- and post-VIM in hemodialysis patients is reproducible and associated with various background factors, and especially post-VIM is independently correlated with cardiovascular mortality. Further studies are necessary to confirm the mechanism of increased post-VIM and clarify whether reducing post-VIM can improve the prognosis of hemodialysis patients.