title: Association of hematocrit value with cardiovascular morbidity and mortality in incident hemodialysis patients.
abstract: BACKGROUND
  Associations between hematocrit values and clinical outcome have been studied with conflicting results in cardiac patients, end-stage renal disease (ESRD) patients, and ESRD patients with cardiac disease. We studied dialysis patients to determine the relationship between hematocrit value and cardiac risk under current Dialysis Outcomes Quality Initiative (DOQI) practices. METHODS; Medicare data were used to study 50,579 incident hemodialysis patients selected from January 1, 1998, to December 31, 1999, who received hemodialysis for 9 months after the onset of ESRD. Patients were divided into groups on the basis of the hematocrit value: < or =30%, >30% to < or =33%, >33% to < or =36%, >36% to < or =39%, and >39%. For hospitalization, the follow-up extended to 21/2 years; for mortality, 3 years.
  
  
  RESULTS
  Compared to patients with hematocrit values of >33% to < or =36%, patients with values of >36% to < or =39% and those with values of >39% had risk ratios for hospitalization due to cardiac disease of 0.92 (95% CI 0.88 to 0.97) and 0.79 (95% CI 0.72 to 0.87), respectively, and risk ratios for death due to cardiac disease of 0.92 (95% CI 0.87 to 0.98) and 0.83 (95% CI 0.74 to 0.93), respectively, in the follow-up period.
  
  
  CONCLUSIONS
  The significant associations we report do not establish a causal relationship between higher hematocrit values and lower risks of cardiac morbidity and mortality. A randomized clinical trial in low-risk patients is needed to establish causality.
authors.affiliation: Nephrology Analytical Services, Minneapolis Medical Research Foundation, Minneapolis, Minnesota 55404, USA.
authors.forename: Suying
authors.initials: S
authors.lastname: Li
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Collins
mesh_terms: D000368:Aged; D002318:Cardiovascular Diseases / Q000401:mortality*; D005260:Female; D006400:Hematocrit; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000401:mortality* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009017:Morbidity; D006435:Renal Dialysis; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors