Anemia in chronic obstructive pulmonary disease: a readmission prognosis factor

Objective: The prevalence of comorbid anemia in patients with COPD ranges from 7.5% to 34%. The aim of this study is to determine if anemia is a risk factor for readmission in COPD patients. Methods: This study analyzed the hospital data of 289,077 adults with acute exacerbations of COPD admitted to the hospital at any public center in Spain, in 2006 and 2007. We calculated the prevalence of anemia and compared readmissions between COPD patients with and without anemia. Multiple regression analyses were carried out with the aim of determining the risk of readmission attributable to anemia, after the correction of possible confounding variables. Results: Of the patients with COPD, 9.8% (n=26,899) had a diagnosis of anemia. Anemic patients were older, more likely to be female and had a greater comorbidity burden than non-anemic individuals. Multiple regression modeling revealed that multiple independent factors were associated with an increased risk of readmission in persons with COPD. Anemia was one of the greatest risks: anemic patients had a 25% higher risk of readmission than non-anemic patients (odds ratio [OR], 1.25; 95% confidence interval [CI] 1.21-1.29). Conclusion: Utilizing an administrative database the authors found that anemia correlates independently with readmission in COPD patients. Limitations: This is a retrospective cohort study and thus subject to multiple forms of bias. Although spirometric evidence of COPD was not available, our case identification methods have been previously validated and found to be accurate in recognizing COPD.