Prognostic value of the hematocrit in patients with severe COPD receiving long-term oxygen therapy.
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.
Chambellan
Arnaud
A
Service de Pneumologie, CHU de Nantes, Boulevard Jacques Monod, 44093 Nantes Cedex 1, France.
Chailleux
Edmond
E
Similowski
Thomas
T
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