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

Abstract

Background: The 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 design: We 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 & participants: 88,153 thrice-weekly-treated HD patients from DaVita dialysis clinics.

Predictors: HD treatment dose (single-pool Kt/V) and treatment time.

Outcomes & other measurements: 5-Year mortality.

Results: Thrice-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.

Limitations: Our results may incorporate uncontrolled confounding. Achieved Kt/V may have different associations than targeted Kt/V.

Conclusions: HD 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.

Figure 1

Secular trends of the quarterly averaged Kt/V and HD treatment over the 5 years of the cohort. Footnote: Standard deviation (SD) are not includes to provide better visualization of the fine trends over time. In the first (q01) vs. last (q20) calendar quarter, Kt/V and HD treatment times (mean±SD) were 1.54±0.33 and 201±61 min vs. 1.55±0.36 and 213±59 min, respectively.

Figure 2

Five-year crude mortality of 88,153 HD patients across four groups of HD treatment times and 4 strata of Kt/V (7/2001–6/2006). Footnote: Crude rate calculations are based on patient numbers in each group.

Figure 3

Death hazard ratios of HD treatment measures in 88,153 HD patients over 5 years (7/2001–6/2006). Left panel: Death hazard ratios of time-averaged Kt/V (single-pool). Right panel: Death hazard ratios of HD treatment time. Footnote: Underlying bars indicate number of HD patients in each group. Note that the survival analyses include interaction terms for sex and race.

Figure 4

Death hazard ratios of time-averaged Kt/V (single-pool) across 4 mutually exclusive groups of HD time in 88,153 HD patients (7/2001–6/2006) Footnote: Note that the survival analyses include interaction terms for sex and race.

Figure 5

Death hazard ratios of time-averaged Kt/V (single-pool) groups across 4 mutually exclusive sex and race categories in 88,153 HD patients (7/2001–6/2006)

Figure 6

Cubic splines (solid lines) and 95% confidence levels (dashed line) of the case-mix adjusted death hazard ratios of time-dependent quarterly varying Kt/V (single-pool) across 4 mutually exclusive sex and race categories in 38,919 HD patients (7/2001–6/2004). Footnote: Note that that the case-mix adjustments include all demographic variables in the time-averaged analyses, plus comorbid states, smoking status and use of catheter.

Figure 7

Death hazard ratios of the 4 HD treatment time groups across 4 mutually exclusive sex and race categories in 88,153 HD patients (7/2001–6/2006)