The Associations Between Dialysis Treatment Time, Mortality, and Hospitalizations in a Large Hemodialysis Cohort

The relationship between hemodialysis treatment time, hospitalization rates, and mortality remains an area of controversy because of difficulties in separating the clinical effects of treatment time from urea clearance and ultrafiltration (UF) volume.

Data were obtained from a retrospective cohort of 146,127 maintenance in-center hemodialysis patients, aged 18 to 89 years, who dialyzed at Fresenius Kidney Care (FKC) clinics between January 1, 2022 and July 1, 2023 with 1-year follow-up after a 30-day run-in period. The patients were stratified into 6 treatment-time groups based on their mean delivered treatment time during the exposure period (180-194, 195-209, 210-224, 225-239, 240-254, and 255-269 minutes). The primary outcome was all-cause mortality; secondary outcomes included all-cause hospitalization rates and hospital length of stay.

Mean dialysis vintage was > 4 years, and few patients likely had residual kidney function. Compared with individuals in the 180-194 minutes group, patients in the 240-254 minutes group had a 27% lower mortality (hazard ratio: 0.73 [0.69-0.76]), whereas patients in the 210-224 minutes and 225-239 minutes groups both had a 19% lower mortality (hazard ratio: 0.81 [0.77-0.85]) and 195-209 minutes group had 15%. These benefits were observed in patient subgroups across a wide range of mean UF volumes as well as with a spKt/V > 1.4, but not for patients with spKt/V < 1.4. In secondary analyses, similar associations were observed between longer treatment times (up to 240-254 minutes) and reduced hospitalization rates and shorter hospital stays.

Longer dialysis treatment times are associated with better survival, fewer hospitalizations, and shorter hospital stays. Although the potential for selection bias cannot be excluded, these survival benefits were realized even when accounting for UF volume and spKt/V > 1.4.