Intradialytic systolic blood pressure changes and risk of mortality

Abstract

Intro: Intradialytic blood pressure changes occur commonly among the hemodialysis (HD) population. Historically, large intradialytic systolic blood pressure (iSBP) decreases have been associated with higher mortality but recent observational studies have not shown this relationship. We sought to evaluate the association of iSBP changes and all-cause mortality. Methods: We examined the change(D) in iSBP (defined as pre-HD SBP minus nadir iSBP) and all-cause mortality (1, 2 and 5-years) in a cohort of incident HD patients (age>/1⁄418yrs) receiving care from a United States based large dialysis organization from January 2007 December 2011 during the 1st 91 days of dialysis (baseline quarter). Ranges of DiSPB and mortality hazard ratio’s (HR) were estimated using Cox regression models with adjustment for case-mix, comorbidities, and lab covariates. A restricted cubic splines model was used to evaluate the continuous relationship between DiSPB and mortality. Results: In a cohort of 112,003 incident HD patients, there were 29,244 observed deaths. Using a reference group of DiSBP 20-30 mmHg (spline median 28 mmHg), we observed that iSBP declines starting at 30 mmHg and greater were not associated with 1 and 2 year mortality. One year mortality HR’s were 0.86 (1.81-0.91), 1.79 (0.73-0.85), and 0.73 (0.66-0.82) for iSBP 31-40, 41-50, and >/1⁄451mmHg respectively. Conclusion: Small declines ( /1⁄421mmHg were observed to be associated with improved survival. Further studies are warranted to characterize these subpopulations and evaluate mechanisms for these associations.