Anemia as a clinical marker of stable chronic obstructive pulmonary disease in the Korean obstructive lung disease cohort

Background: Anemia is a major co-morbidity in chronic obstructive pulmonary disease (COPD). However, the mechanism of development for anemia and the impact of anemia on the prognosis of COPD remain poorly understood. Therefore, this study attempted to evaluate the prognostic role of anemia on the clinical course of COPD and investigate the factors linked with the serum hemoglobin level in COPD. Methods: We analyzed 407 COPD patients enrolled in the Korean obstructive lung disease (KOLD) cohort at 16 hospitals in Korea recruited over 9 years. Multivariate Cox regression analysis was performed to find independent predictors of survival and multivariate logistic regression analyses were done to find independent factors. Results: Anemic COPD were older with lower body mass index (BMI) (P < 0.001), lower serum cholesterol level (P=0.001), lower serum albumin level (P < 0.001), and shorter 6-minute walking distance (P=0.046) compared to non-anemic COPD. A multivariate Cox regression analysis revealed that age (P=0.002), BMI (P=0.001), post-bronchodilator forced expiratory volume in 1 second (FEV1) (P=0.007), 6-minute walk distance (P=0.008), anemia (P=0.025) were significant predictors for all-cause mortality. In multivariate regression analysis, older age (P < 0.001), female gender (P=0.001), lower BMI (P=0.016), and lower serum albumin level (P < 0.001) were independent factors associated with lower serum hemoglobin level. Conclusions: Our data showed that anemia was an independent risk factor for mortality in COPD, and aging, lower serum albumin level, and lower BMI were independent factors associated with lower serum hemoglobin level.