Abstract: 【Abstract】Purpose The roles of chronic kidney disease (CKD) and chronic obstructive pulmonary disease (COPD) on hemoglobin level are mutually contradicted. The aim of this study was to analyze the hemoglobin level in hospitalized patients with the both conditions and the detrimental effect of abnormal hemoglobin levels. Methods Clinical data were recruited from electronic medical records in the 12 hospitals. CKD was diagnosed by the creatinine estimated glomerular filtration rate. The mean hemoglobin level during hospitalization was used for the investigation. Results CKD occurred in 12.7% of hospitalized COPD patients. The incidences of anemia and polycythemia were 39.5% and 2.9%, respectively. With the progression of CKD, the incidence of anemia increased, while the incidence of polycythemia decreased. Univariate regression showed that CKD and both types of abnormal hemoglobin levels were associated with in-hospital mortality. After adjusted by elderly and the Charlson comorbidity score, anemia increased the risk of in- hospital mortality in patients without CKD (odds ratio 1.460, 95% CI 1.278～1.667,P＜0.001). However, anemia was not related to the mortality in CKD patients. Polycythemia was associated with the mortality in patients without CKD, early CKD and advanced CKD (odds ratios were 2.191, 2.034 and 3.687, respectively; 95% CIs were 1.654～2.902, 1.169～3.541,P=0.012 and 1.432～9.490,P＜0.007, respectively). Conclusion CKD aggravated anemia in hospitalized COPD patients. Anemia was a risk factor for in-hospital mortality in patients without CKD. Polycythemia was associated with the mortality in all COPD patients.

Key words: chronic kidney disease, chronic obstructive pulmonary disease, anemia, polycythemia, epidemiology, in-hospital death