Gender, low K t/ V , and mortality in J apanese hemodialysis patients: Opportunities for improvement through modifiable practices

Abstract

Guidelines have recommended single pool K t/ 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 J apan than many other countries, though survival is longer in J apan. We examined trends in low K t/ V , dialysis practices associated with low K t/ V , and associations between K t/ V and mortality overall and by gender in Japanese dialysis patients. We analyzed 5784 HD patients from J apan 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 K t/ V . Logistic models also were used to estimate the proportion of low K t/ V cases attributable to various treatment practices. Multivariable C ox regression was used to estimate the associations of low K t/ V , blood flow rate ( BFR ), and treatment time ( TT ), with all‐cause mortality. From 1999 to 2009, the prevalence of low K t/ 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 K t/ V . Fifteen percent of low K t/ V cases were attributable to BFR <200 and 13% to TT <240, compared to only 3% for DFR <500. Lower K t/ V was associated with elevated mortality, more so among women (hazard ratio [ HR ] = 1.13 per 0.1 lower K t/ V , 95% CI : 1.07–1.20) than among men ( HR = 1.06 per 0.1 lower K t/ V , 95% CI : 1.00–1.12). The relatively large proportion of low K t/ V cases in J apanese 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 K t/ V with elevated mortality suggest that modification of these practices may further improve survival for J apanese HD patients.