P1253ASSOCIATION OF PREDIALYSIS PULSE PRESSURE (PP) AND ITS INTRADIALYTIC VARIATIONS IN 5 YEAR MULTICENTER COHORT STUDY
Authors: Shilo Valeriy , Drachev Ivan 
Published: June 2020

Abstract

Background and Aims
Elevated PP, as a surrogate marker of elastic properties the arteries vessel wall, is important characteristics of the cardiovascular system and may be associated with poor survival both in the general eldery population with arterial hypertension and in patients on maintenance hemodialysis (HD). It has been shown, that increase predialysis PP in HD patients was associated with a higher risk of hospitalization or death, but the relationship between PP changes during HD was not well investigated in large prospective cohort studies. The aim of the study was to assess the effect of elevated predialisis PP and its intradialytic PP variations on survival in the Kaplan-Meir curves and in the Cox regression models.

Method
The retrospective cohort included patients who underwent maintenance HD in the large chain of B. Braun Avitum free standing HD units in Russia from 2011 to 2016 years (n = 3704). The mean age of the patients was 54,8±13,7 years, 45% were women and 55% men. All patients were on B. Braun Dialog+ Evolution dialysis machines with Adimea option for on-line KT/V measurement and synthetic alpha-polysulphone Xevonta series dialyzers (surface area 1,8, 2,0 and 2,3 sq. m.) The delivered dialysis dose, according to the Daugirdas 2nd generation formula was 1,6 ± 0.23 (spKt/V). Statistical analysis in a Kaplan-Meier curves and proportional Cox regression model were performed. The study used averaged BP data measured over the entire observation period and PP calculation. Patients were divided into subgroups according PP calculation &lt;35, 35-55, 55-75 and more than 75 mm Hg. Variations in intradialytic PP (ΔPP) were divided into groups according to PP average change during HD procedure: -25 and lower decrease, -25 - -10, -10 - 0, 0 - 10, and 10 - 25 increase, mm Hg.

Results
From total cohort of 3704 patients, 207 (5,6%) has highly elevated PP (&gt; 75 mmHg) and another 1549 (41,8%) has slightly elevated PP (55-75 mm hg). During the study, 393 deaths occurred. The Kaplan-Meyer survival curves clearly demonstrate that the worst survival rate occurs in the subgroup of patients with the markedly elevated predialysis PP (n=207, 35 deaths; HR = 1,7 CI = 1,3 – 2,6; p &lt;0,001; Pic. 1). Then we analyze association of intradialytic PP changes and mortality in total cohort (n=3704) and the subgroups with elevated PP (n=1756). Both marked PP drop down and PP increase during HD worsen survival: the most poor demonstrate patients with highest decrease in PP (-25 mm Hg and more) and then with highest increase in PP (+10-25 mm hg) within HD procedure (Pic. 2).
In unadjusted Cox model predialytic PP and survival remain significant (p=0,01), but not PP changes (p=0,3). After multivariable adjustments in the Cox regression model with main demographic factors (age, treatment duration) and key laboratory indices (spKT/V, urea, creatinine, hemoglobin, albumin, Ca, PO4, PTH) there were no association between both predialysis PP and PP changes and mortality (p=0,9 and 0,1, respectively). Among the independent risk factors in our model, highest hazard ratio affecting survival has for ultrafiltration (UF) speed both for predialytic PP and PP variations (tabl. 1 and table 2).

Conclusion
In our study PP and its intradialytic variations show statistical significant association with mortality in single factor survival analysis and in unadjusted Cox regression model, but were not independent factor in adjusted multivariate HR model. UF speed has the highest impact on mortality in our model. We can hypothesize, that patients with elevated PP are vulnerable for high UF rate and prone for intradialytic hypotension and higher mortality on maintenance HD.