Chest
Volume 128, Issue 3, September 2005, Pages 1201-1208
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Clinical Investigations
Prognostic Value of the Hematocrit in Patients With Severe COPD Receiving Long-term Oxygen Therapy

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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 Pao2 < 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 Paco2 (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 ≥ 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.

Section snippets

Organization of the ANTADIR Observatory

The ANTADIR is a French national nonprofit associative network of 23 regional associations founded in 1981 to ensure health-care support and technical follow-up to disabled patients requiring domiciliary oxygen support, mechanical ventilation, or continuous positive airway pressure. Since its foundation, ANTADIR has maintained a comprehensive demographic database or “observatory,”14 providing a unique national register allowing epidemiologic surveys in large cohorts of patients with various

Hematocrit

Anemia can be defined by a hematocrit < 39% in men and < 36% in women.17 According to this definition, the prevalence of anemia in the cohort studied was 12.6% in men and 8.2% in women (but 18.5% of the women had a hematocrit < 39%). The prevalence of a hematocrit value ≥ 55% was 8.4% (men, 8.9%; women, 5.9%). Hematocrit was significantly higher in men than in women (t = 5.6, p < 0.001), and was negatively correlated with age (r = −0.245, p < 0.001) and positively correlated with Paco2 (r =

Discussion

This study shows that in a large population of COPD patients treated with LTOT, the prevalence of a low hematocrit at the time the prescription of oxygen is far from negligible (12.6% of the men and 18.5% of the women meeting the World Health Organization definition of anemia [hematocrit < 39%]17). In this particular population, the study also points to a strong association between hematocrit and long-term survival in this population.

These findings seem to contrast with commonly held views.

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    Fédération Antadir, 66 Bd St-Michel, 75006 Paris, France.

    Dr. Chambellan was supported by a grant from the Association Regionale de l’Insuffisance Respiratoire des Pays de la Loire.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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