title: A prospective multicentre study of the role of anaemia as a risk factor in haemodialysis patients: the MAR Study.
abstract: BACKGROUND
  Retrospective studies have shown hospitalization and mortality rates during haemodialysis (HD) to be associated with anaemia.
  
  
  METHODS
  The prospective, multicentre Morbidity-and-mortality Anaemia Renal (MAR) study was designed to establish the burden of anaemia by controlling for other risk factors. Charlson index was used for comorbid adjustment. Finally, 1428 patients from 119 centres (60% men, aged 64.4 years, time on HD 15.3 months, Charlson comorbidity index 6.5 +/- 2.3) completed follow-up. They had hypertension (75.8%), diabetes mellitus (25.9%), heart failure (13.9%) and coronary disease (16.7%). Of the total patients, 94.8% were receiving erythropoietin (111.6 +/- 70.6 U/kg/week) and 76.7% i.v. iron, and haemoglobin (Hb) at inclusion was 11.7 +/- 1.5 g/dl.
  
  
  RESULTS
  Hospitalization rate was 1.1 admissions/patient/year. Yearly mortality was 12% [35% cardiovascular (CV)]. The relative risk and confidence interval (CI) for hospitalization and death were 0.86 (0.81-0.91) and 0.82 (0.73-0.91), respectively, per 1 g/dl increase in initial Hb after adjustment for comorbidity, vintage, aetiology, access type, albumin and Kt/V. The probability of remaining free from hospitalization (CI) was 0.34 (0.27-0.41) for initial Hb <10 g/dl, 0.47 (0.41-0.53) for Hb 10-11 g/dl, 0.54 (0.49-0.59) for Hb 11-12 g/dl, and 0.63 (0.59-0.67) for Hb >12 g/dl. Same analysis for patient survival was 0.77 (0.71-0.83) for Hb <10 g/dl vs 0.82 (0.77-0.87) for Hb 10-11 vs 0.89 (0.86-0.92) for Hb 11-12 vs 0.92 (0.90-0.94) for Hb > 12 g/dl, P < 0.001. The Cox regression model for hospitalization-free survival included the risk factors initial Hb (relative risk 0.86 per 1 g/dl increase, P < 0.001) Charlson, albumin and prior CV event.
  
  
  CONCLUSIONS
  Hb level predicted 1-year-survival and hospitalization. This effect persisted after adjustment for comorbidity and other prognostic factors.
authors.affiliation: Jefe Servicio de Nefrología, Fundación Hospital Alcorcón, Avda Villaviciosa 1, 28922 Alcorcón (Madrid), Spain. jmportoles@fhalcorcon.es
authors.forename: José
authors.initials: J
authors.lastname: Portolés
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: López-Gómez
authors.forename: Pedro
authors.initials: P
authors.lastname: Aljama
mesh_terms: D000368:Aged; D000740:Anemia / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006454:Hemoglobins / Q000378:metabolism; D006760:Hospitalization / Q000639:trends; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000453:epidemiology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D006435:Renal Dialysis / Q000009:adverse effects*; D012307:Risk Factors; D013030:Spain / Q000453:epidemiology; D015996:Survival Rate / Q000639:trends
chemical_list: D006454:Hemoglobins