title: Gender, low Kt/V, and mortality in Japanese hemodialysis patients: opportunities for improvement through modifiable practices.
abstract: Guidelines have recommended single pool Kt/V > 1.2 as the minimum dose for chronic hemodialysis (HD) patients on thrice weekly HD. The Dialysis Outcomes and Practice Patterns Study (DOPPS) has shown that "low Kt/V" (<1.2) is more prevalent in Japan than many other countries, though survival is longer in Japan. We examined trends in low Kt/V, dialysis practices associated with low Kt/V, and associations between Kt/V and mortality overall and by gender in Japanese dialysis patients. We analyzed 5784 HD patients from Japan DOPPS (1999-2011), restricted to patients dialyzing for >1 year and receiving thrice weekly dialysis. Logistic regression models estimated the relationships of patient characteristics with Kt/V. Logistic models also were used to estimate the proportion of low Kt/V cases attributable to various treatment practices. Multivariable Cox regression was used to estimate the associations of low Kt/V, blood flow rate (BFR), and treatment time (TT), with all-cause mortality. From 1999 to 2009, the prevalence of low Kt/V declined in men (37-27%) and women (15-10%). BFR <200 mL/min, TT <240 minutes, and dialyzate flow rate (DFR) < 500 mL/min were common (35, 13, and 19% of patients, respectively) and strongly associated with low Kt/V. Fifteen percent of low Kt/V cases were attributable to BFR <200 and 13% to TT <240, compared to only 3% for DFR <500. Lower Kt/V was associated with elevated mortality, more so among women (hazard ratio [HR] = 1.13 per 0.1 lower Kt/V, 95% CI: 1.07-1.20) than among men (HR = 1.06 per 0.1 lower Kt/V, 95% CI: 1.00-1.12). The relatively large proportion of low Kt/V cases in Japanese facilities may potentially be reduced 30% by increasing BFR to 200 mL/min and TT to 4 hours thrice weekly in HD patients. Associations of low Kt/V with elevated mortality suggest that modification of these practices may further improve survival for Japanese HD patients.
authors.affiliation: Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Kimata
authors.forename: Angelo
authors.initials: A
authors.lastname: Karaboyas
authors.forename: Brian A
authors.initials: BA
authors.lastname: Bieber
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Pisoni
authors.forename: Hal
authors.initials: H
authors.lastname: Morgenstern
authors.forename: Brenda W
authors.initials: BW
authors.lastname: Gillespie
authors.forename: Akira
authors.initials: A
authors.lastname: Saito
authors.forename: Tadao
authors.initials: T
authors.lastname: Akizawa
authors.forename: Shunichi
authors.initials: S
authors.lastname: Fukuhara
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Robinson
authors.forename: Friedrich K
authors.initials: FK
authors.lastname: Port
authors.forename: Takashi
authors.initials: T
authors.lastname: Akiba
mesh_terms: D000368:Aged; D005260:Female; D015312:Hemodialysis Solutions / Q000008:administration & dosage* / Q000378:metabolism; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007676:Kidney Failure, Chronic / Q000628:therapy; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D006435:Renal Dialysis / Q000379:methods* / Q000401:mortality*; D012737:Sex Factors
chemical_list: D015312:Hemodialysis Solutions
keywords: Hemodialysis; Kt/V, mortality; adequacy; survival; treatment time