Greater Haemodialysis Exposure ('quotidian Haemodialysis') Has Different Mortality Associations by Patient Age Group

Background. Worldwide, most people requiring kidney replacement therapy receive haemodialysis (HD) three times per week. Greater HD time and/or frequency may improve survival, but implementation requires understanding potential benefits across the range of patients. Methods. Using data from the Australia and New Zealand Dialysis and Transplant Registry, we assessed whether quotidian HD (defined as >3 sessions/week and/or >5 h/session) was associated with reduced mortality in adult patients. The primary outcome of all-cause mortality was analysed by a time-varying Cox proportional hazards model with quotidian HD as the exposure of interest. Results. Of 24 138 people who received HD between 2011 and 2019, 2632 (10.9%) received quotidian HD at some stage. These patients were younger, more likely male and more likely to receive HD at home. Overall, quotidian versus standard HD was associated with a decreased risk for all-cause mortality {crude hazard ratio [HR] 0.50 [95% confidence interval (CI) 0.45-0.56]}, but an interaction between quotidian HD and age was identified (P = .005). Stratified by age groups and splitting follow-up time where proportional hazards were violated, the corresponding HR compared with standard HD was 2.43 (95% CI 1.56-3.79) for people >75 years of age in the first year of quotidian HD, 1.52 (95% CI 0.89-2.58) for 1-3 years and 0.95 (95% CI 0.51-1.78) for >= 3 years. There was no significant survival advantage in younger people. Conclusions. Although quotidian HD conferred survival benefit in crude analyses, people >= 75 years of age had greater mortality with quotidian HD than standard HD. The mortality benefit in younger people was attenuated when adjusted for known confounders. [GRAPHICS]