PS-BPC04-1: CHARACTERISTICS OF MONTH-BY-MONTH BLOOD PRESSURE VARIABILITY IN HEMODIALYSIS PATIENTS

Abstract

Objectives: It is well known that blood pressure (BP) exhibits BP variation in patients with hemodialysis (HD). We have previously reported that high visit-to-visit blood pressure variability is independently correlated with cardiovascular mortality in maintenance HD patients. However, the characteristics of long-term BP variability remains to be elucidated in these patients. The present study, therefore aimed to investigate the characteristics of month-by-month blood pressure variability, as an indicator of long-term blood pressure variability, and the relationship between month-by-month blood pressure variability and cardiovascular mortality in these patients. Design and method: A total of 324 maintenance HD patients, who could be followed for 60 months, were recruited. We used variation independent of the mean (VIM), which was estimated using systolic BP (SBP) in pre-dialysis and post-dialysis at the beginning of the month in 12 consecutive months (pre-VIM-SBP and post-VIM-SBP), as an index of month-by-month BP variability. We also estimated the average of 12 values of differences between the highest and lowest SBP values during a dialysis session (average Δ SBP) and the difference between SBP in January and February and SBP in July and August (seasonal variability of SBP). We investigated (1) the reproducibility of these values, (2) the relationship between these values and background factors, and (3) the association between these values and mortality. Results: (1) Pre-VIM-SBP and post-VIM-SBP showed significant reproducibility (intraclass correlation, 0.456 (P < 0.001) and 0.522 (P < 0.001), respectively]. Seasonal variability of pre-SBP and Δ SBP was observed both at beginning / after 12 months [5.0 (-5.0–19.0) / 5.3 ± 18.3, 7.2 ± 16.7 / 5.0 ± 12.8, respectively]. (2) Higher pre-VIM-SBP was associated with higher interdialytic weight gain and poor nutritional status. Higher post-VIM-SBP was associated with glucose intolerance, higher interdialytic weight gain and poor nutritional status. Higher Δ SBP was associated with glucose intolerance and higher interdialytic weight gain. (3) Higher post-VIM-SBP was associated with a higher rate of cardiovascular deaths independent of other factors (hazard ratio: 1.104, 95% confidence interval: 1.011–1.207, P = 0.028). Conclusions: Month-by-month blood pressure variability in HD patients is reproducible and associated with various background factors. Month-by-month blood pressure variability in post-dialysis SBP is independently correlated with cardiovascular mortality. Further studies are necessary to confirm the mechanism of increased month-by-month blood pressure variability and to clarify whether reducing month-by-month blood pressure variability will improve the prognosis for HD patients.