Boutou AK, Karrar S, Hopkinson NS, Polkey MI. Anemia and survival in chronic obstructive pulmonary disease: a dichotomous rather than a continuous predictor.
ACTA ACUST UNITED AC 2012;
85:126-31. [PMID:
22759351 DOI:
10.1159/000338792]
[Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 04/10/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND
Chronic obstructive pulmonary disease (COPD) is a disorder characterized by high mortality. Hemoglobin (Hb) concentration has a prognostic impact on COPD patients receiving long-term oxygen treatment, but its value as an independent predictor of survival among stable COPD outpatients has not been fully clarified by previous studies.
OBJECTIVES
To investigate the potential association between anemia and survival in a cohort of stable COPD outpatients.
METHODS
A cohort of stable COPD patients, who had had their first spirometry, blood count and serum chemistry profile done between October 1999 and November 2010 were retrospectively analyzed. Patients with heart failure, renal impairment, malignancy, recent hemorrhage and other causes of anemia were excluded. Variables that were found to be univariately associated with survival entered a multivariate stepwise Cox regression analysis model, to allow independent predictors of survival to be identified.
RESULTS
Of 294 patients (67.9 ± 9.8 years old, 64.6% male) 15.6% were anemic (Hb <13 g/dl). The median survival differed significantly between anemic [68.7 (18.1-91.5) months] and nonanemic [79.8 (57.5-98.4) months, p = 0.035] individuals. Independent predictors of mortality in the total population were anemia [hazard ratio (HR) 1.87, 95% confidence interval (CI) 1.06-3.29], age (HR 1.08, 95% CI 1.04-1.12) and forced expiratory volume in 1 s (FEV(1)) % predicted (HR 0.94, 95% CI 0.92-0.97); the Hb concentration was neither univariately nor multivariately associated with mortality.
CONCLUSION
This is the first study to indicate that anemia (but not the Hb value) is independently associated with survival in stable COPD outpatients. It would be better to treat this as a categorical variable in future scoring systems.
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