Hemodialysis timing, survival, and cardiovascular outcomes in the Hemodialysis (HEMO) Study

Background: The timing of medical therapies has been shown to influence the outcomes and side effects of treatments for disease. This report examines the extent to which hemodialysis treatment time of day was associated with cardiovascular mortality and morbidity and all-cause mortality in a secondary analysis of the Hemodialysis Study. Methods: Dialysis start time defined dialysis shift: morning beginning between 0400 and 0930 hours (n = 822); midday, between 0930 and 1530 hours (n = 851); and evening, between 1530 and 2200 hours (n = 172). Outcome measures included all-cause mortality, cardiac death, composite end point of all-cause mortality or first cardiac hospitalization, and composite end point of first cardiac hospitalization or cardiac death. Results: Morning hemodialysis was associated with a lower likelihood of cardiovascular events compared with the evening shift in all-cause mortality or first cardiac hospitalization (evening versus morning, relative risk [RR], 1.29; 95% confidence interval [CI], 1.01 to 1.65; P = 0.043), as well as first cardiac hospitalization or cardiac death (evening versus morning, RR, 1.44; 95% CI, 1.11 to 1.89; P = 0.007). No differences were noted in the other 2 outcomes, and there was no statistically significant difference between the morning and midday shifts. Although crude mortality rates were greater in the midday compared with morning (RR, 1.21; 95% CI, 1.05 to 1.39; P = 0.008), this association was attenuated after adjustment (RR, 1.04; 95% CI, 0.89 to 1.22; P = 0.64). Conclusion: Making extensive adjustment for patient characteristics, this report does not support the association of lower all-cause mortality with morning hemodialysis or a particular benefit for older patients.