Initial Session Duration and Mortality Among Incident Hemodialysis Patients

Background: The association of dialysis session duration with mortality in patients undergoing maintenance hemodialysis is unclear. We compared mortality rates of patients treated in dialysis facilities that used initial session durations of either ≥ 4 versus 3 hours for all incident patients.

Study Design: Retrospective cohort study.

Settings & Participants: Patients with end-stage renal disease beginning maintenance hemodialysis therapy in January 2006 to December 2010 and followed up through December 2012, including 39,172 patients in 852 facilities who initiated treatment for ≥ 4 hours and 47,721 patients in 631 facilities who initiated treatment for 3 hours.

Predictor: Initial session duration of ≥ 4 hours versus 3 hours.

Outcome: 2- and 1-year mortality rates.

Results: Total numbers of deaths observed within 2 years after initiating dialysis therapy were 8,945 in the ≥ 4-hour group and 15,624 in the 3-hour group. The corresponding numbers of deaths observed within 1 year were 5,492 and 10,372, respectively. The 2-year adjusted HR in the ≥ 4-hour versus 3-hour group was 0.79 (95% CI, 0.73-0.86). The corresponding 1-year adjusted HR was 0.77 (95% CI, 0.70-0.84). Results were robust when analyses were restricted to specific subgroups of patients classified by age, sex, race, and select clinical characteristics.

Limitations: We did not observe hemodialysis duration in sessions subsequent to initiation. We only included patients treated in facilities with uniform session length (at initiation) for all their patients. Furthermore, we lacked information for dialysis dosage and patients' baseline residual kidney function.

Conclusions: Patients in facilities routinely initiating hemodialysis therapy for ≥ 4 hours may have substantially lower mortality as compared with patients in facilities initiating for only 3 hours of treatment.