title: Effect of prolonged weekly hemodialysis on survival of maintenance hemodialysis patients: a meta-analysis of studies.
abstract: OBJECTIVE
  Use of prolonged nocturnal or daytime hemodialysis (PHD, more than 12 h per week) is associated with improvement of some clinical parameters relative to conventional hemodialysis (CHD, 4 h sessions, thrice weekly), but the effect on survival is unclear. The purpose of this meta-analysis is to determine whether PHD improves survival of patients undergoing maintenance HD.
  
  
  METHODS
  Systematic review of observational studies by meta-analysis.
  
  
  METHODS
  Electronic searches in MEDLINE (PubMed, 1966-2012), EMBASE (1974-2012), www.clinicaltrials.gov, and the Cochrane Controlled Clinical Trials Register Database.
  
  
  METHODS
  All prospective or retrospective studies were considered eligible if they were cohort studies or observational studies that compared CHD with PHD (more than 12 h of HD per week due to more HD sessions or increased duration of HD sessions) and the final outcome was all-cause death or mortality.
  
  
  RESULTS
  Thirteen studies with a total of 85,722 participants (10,285 PHD patients, 75,437 CHD patients) met the inclusion criteria. Summary estimates indicated that PHD was associated with decreased risk of mortality (OR = 0.72, 95% CI 0.64-0.81, p < 0.00001). Analysis of residual confounders of pooled results from six retrospective studies indicated that PHD patients were less likely to have low hemoglobin (11.7 vs. 11.2 g/dl, p < 0.01), younger (51.2 vs. 58.8 years, p < 0.01), less likely to have diabetes (27.1 vs. 40.8%, p < 0.01), and less likely to use a catheter (18.4 vs. 27.1%, p < 0.01), so these may have affected the outcome measure in these studies.
  
  
  CONCLUSIONS
  PHD is associated with improved survival relative to CHD, although residual confounders have affected this relationship in observational studies. Large, multicenter randomized, controlled trials are needed to confirm our results.
authors.affiliation: Division of Nephrology, Shanghai Pudong Hospital, Fudan University, Shanghai, PR China.
authors.forename: Hui Min
authors.initials: HM
authors.lastname: Jin
authors.forename: Li Li
authors.initials: LL
authors.lastname: Guo
authors.forename: Xiao Li
authors.initials: XL
authors.lastname: Zhan
authors.forename: Yu
authors.initials: Y
authors.lastname: Pan
mesh_terms: D006801:Humans; D006435:Renal Dialysis / Q000401:mortality*; D013997:Time Factors