title: Prognostic value of the hematocrit in patients with severe COPD receiving long-term oxygen therapy.
abstract: BACKGROUND
  Although traditionally associated with polycythemia, COPD has a systemic inflammatory component that could interfere with erythropoiesis. This study describes the distribution and prognostic value of the hematocrit in patients with severe COPD receiving long-term oxygen therapy (LTOT).
  
  
  METHODS
  A total of 2,524 patients with COPD, FEV1/vital capacity (VC) < 70%, FEV1 < 80% of predicted, and Pa(O2) < 7.3 kPa in whom a hematocrit was available at entry was identified between 1980 and 1999 in the French Association Nationale pour le Traitement à Domicile de l'Insuffisance Respiratoire chronic respiratory insufficiency and home-care database (male/female ratio, 5/1; mean +/- SD age, 68 +/- 10 years for men, and 70 +/- 10 years for women). Correlations between hematocrit, demographic data, and pulmonary function data were examined. A multivariate Cox proportional hazard regression was performed to identify prognostic factors.
  
  
  RESULTS
  Mean hematocrit was 45.9 +/- 7.0% in men and 43.9 +/- 6.0% in women (< 39% in 12.6% of men, and < 36% in 8.2% of women) according to the World Health Organization definition of anemia. Hematocrit was negatively correlated with age (r = - 0.245) and FEV1/VC (r = - 0.068) and was positively correlated with Pa(CO2) (r = 0.161) and body mass index (r = 0.127). Multivariate analysis found hematocrit to be an independent predictor of survival, hospital admission rate, and cumulative duration of hospitalization. The 3-year survival was 24% (95% confidence interval, 16 to 33%) when the hematocrit was < 35%, and 70% (63 to 76%) when the hematocrit was > or = 55%.
  
  
  CONCLUSIONS
  A low hematocrit is not uncommon in LTOT/COPD patients. Hematocrit is negatively associated with mortality and morbidity. Whether the association is causative or not and whether or not corrective measures are warranted remain to be determined.
authors.affiliation: Service de Pneumologie, CHU de Nantes, Boulevard Jacques Monod, 44093 Nantes Cedex 1, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Chambellan
authors.forename: Edmond
authors.initials: E
authors.lastname: Chailleux
authors.forename: Thomas
authors.initials: T
authors.lastname: Similowski
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000150:complications / Q000175:diagnosis / Q000401:mortality*; D005260:Female; D006400:Hematocrit; D006801:Humans; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D011237:Predictive Value of Tests; D011379:Prognosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000401:mortality / Q000628:therapy*; D016019:Survival Analysis