Association of hemodialysis treatment time and dose with mortality and the role of race and sex.

BackgroundThe association of survival with characteristics of thrice-weekly hemodialysis (HD) treatment, including dose or duration of treatment, has not been completely elucidated, especially in different race and sex categories.Study designWe examined associations of time-averaged and quarterly varying (time-dependent) delivered HD dose and treatment time and 5-year (July 2001-June 2006) survival.Setting & participants88,153 thrice-weekly-treated HD patients from DaVita dialysis clinics.PredictorsHD treatment dose (single-pool Kt/V) and treatment time.Outcomes & other measurements5-Year mortality.ResultsThrice-weekly treatment time < 3 hours (but > or = 2.5 hours) per HD session compared with > or = 3.5 hours (but < 5 hours) was associated with increased death risk independent of Kt/V dose. The greatest survival gain of higher HD dose was associated with a Kt/V approaching the 1.6-1.8 range, beyond which survival gain was minimal, nonexistent, or even tended to reverse in African American men and those with 4-5 hours of HD treatment. In non-Hispanic white women, Kt/V > 1.8 continued to show survival advantage trends, especially in time-dependent models.LimitationsOur results may incorporate uncontrolled confounding. Achieved Kt/V may have different associations than targeted Kt/V.ConclusionsHD treatment dose and time appear to have different associations with survival in different sex or race groups. Randomized controlled trials may be warranted to examine these associations across different racial and demographic groups.