Study on Dialysis Session Length and Mortality in Maintenance Hemodialysis Patients: The Q-Cohort Study

OBJECTIVES: Hemodialysis (HD) time has been recognized as an important factor in dialysis adequacy. However, few studies have reported on associations between HD time and prognosis among maintenance HD patients. We present some findings from a prospective cohort study, the -Q-Cohort Study, which was set up to explore risk factors for mortality in Japanese HD patients. We hypothesized that HD ≥5 h was associated with a significant survival advantage compared with HD < 5 h. The present study examined association between HD time and mortality in Japanese HD patients. METHODS: The prospective multicenter Q-Cohort Study was conducted between December 2006 and December 2010, following 3,456 Japanese HD patients for 4 years. We examined the association between HD time and prognosis using Cox proportional hazards modeling. Propensity scores were calculated using logistic regression. RESULTS: During follow-up, 566 patients died from any cause. Patients with HD ≥5 h (n = 2,141) showed -significantly lower risk of all-cause death (hazards ratio = 0.82; 95% CI 0.68-0.99) than those with HD < 5 h (n = 1,315), after adjusting for confounding risk factors. This -association remained significant using a propensity score-based approach. After stratifying the analysis by patient age in 10-year increments, this finding remained -significant only in patients who were ≥80 years of age. CONCLUSION: Our results suggest that HD ≥5 h has a more favorable effect on mortality than HD < 5 h.