Abstract: Objective To compare the association between intradialytic hypotension (IDH) using different definitions and all- cause mortality in maintenance hemodialysis (MHD) patients. Methods Data from 407 patients were retrospectively analyzed. The K-M curves based on the 9 different definitions were established, and the cutoff value for the incidence of IDH with maximum difference in the K-M curve was used to distinguish frequent IDH from non-frequent IDH. Cox proportional hazard regression model was conducted to compare the correlation between frequent IDH and all-cause mortality. C-index, Akaike Information Criterion(AIC), Net Reclassification Index (NRI) and Integrated Discrimination Improvement (IDI) were used to evaluate efficiency and quality of the model. Finally, the dose-response effect between the frequency of IDH and allcause mortality was explored by strict cubic spline regression. Results A total of 198,883 dialysis data were collected during the 56-month follow-up period, and 35 patients (8.6%) died with an average death rate of 2.6 per 100 person-years. The proportion of never having IDH using an IDH definition ranged from 0% to 46.4%, and the average incidence of IDH ranged from 0.7% to 46.0%. After adjusting for confounding variables, frequent IDH that defined by the British Kidney Association (UKKA) guidelines was significantly associated with all-cause mortality (HR=6.762, 95% CI:3.272～13.977, P＜0.001). The C-index, AIC, NRI and IDI of the model were 0.749, 380.957, 0.381 and 0.093 respectively; there was a significant non-linear relationship between the frequency of IDH and the risk of all- cause mortality (Wald χ2=3.875, P=0.049). Conclusion
IDH is common, and its incidence varies using different definitions. Redefinition of IDH may reduce the variation. Using the UKKA guidelines, the risk of all-cause mortality increased with the frequency of IDH. Frequent IDH was significantly associated with all-cause mortality, which is closely related to clinical practice to reveal the association between IDH and all-cause mortality.

Key words: Intradialytic Hypotension, Hemodialysis, All-cause Mortality