title: Longer treatment time and slower ultrafiltration in hemodialysis: associations with reduced mortality in the DOPPS.
abstract: Longer treatment time (TT) and slower ultrafiltration rate (UFR) are considered advantageous for hemodialysis (HD) patients. The study included 22,000 HD patients from seven countries in the Dialysis Outcomes and Practice Patterns Study (DOPPS). Logistic regression was used to study predictors of TT > 240 min and UFR > 10 ml/h/kg bodyweight. Cox regression was used for survival analyses. Statistical adjustments were made for patient demographics, comorbidities, dose of dialysis (Kt/V), and body size. Europe and Japan had significantly longer (P < 0.0001) average TT than the US (232 and 244 min vs 211 in DOPPS I; 235 and 240 min vs 221 in DOPPS II). Kt/V increased concomitantly with TT in all three regions with the largest absolute difference observed in Japan. TT > 240 min was independently associated with significantly lower relative risk (RR) of mortality (RR = 0.81; P = 0.0005). Every 30 min longer on HD was associated with a 7% lower RR of mortality (RR = 0.93; P < 0.0001). The RR reduction with longer TT was greatest in Japan. A synergistic interaction occurred between Kt/V and TT (P = 0.007) toward mortality reduction. UFR > 10 ml/h/kg was associated with higher odds of intradialytic hypotension (odds ratio = 1.30; P = 0.045) and a higher risk of mortality (RR = 1.09; P = 0.02). Longer TT and higher Kt/V were independently as well as synergistically associated with lower mortality. Rapid UFR during HD was also associated with higher mortality risk. These results warrant a randomized clinical trial of longer dialysis sessions in thrice-weekly HD.
authors.affiliation: Division of Nephrology and Kidney Epidemiology and Cost Center, University of Michigan, Ann Arbor, Michigan 48103-4262, USA. rsaran@umich.edu
authors.forename: R
authors.initials: R
authors.lastname: Saran
authors.forename: J L
authors.initials: JL
authors.lastname: Bragg-Gresham
authors.forename: N W
authors.initials: NW
authors.lastname: Levin
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Twardowski
authors.forename: V
authors.initials: V
authors.lastname: Wizemann
authors.forename: A
authors.initials: A
authors.lastname: Saito
authors.forename: N
authors.initials: N
authors.lastname: Kimata
authors.forename: B W
authors.initials: BW
authors.lastname: Gillespie
authors.forename: C
authors.initials: C
authors.lastname: Combe
authors.forename: J
authors.initials: J
authors.lastname: Bommer
authors.forename: T
authors.initials: T
authors.lastname: Akiba
authors.forename: D L
authors.initials: DL
authors.lastname: Mapes
authors.forename: E W
authors.initials: EW
authors.lastname: Young
authors.forename: F K
authors.initials: FK
authors.lastname: Port
mesh_terms: D000328:Adult; D016208:Databases, Factual; D006801:Humans; D006435:Renal Dialysis / Q000379:methods* / Q000401:mortality; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D014462:Ultrafiltration / Q000379:methods*