Purpose Anaemia is increasingly being linked to chronic obstructive pulmonary disease (COPD) as comorbidity with erythropoietin resistance secondary to chronic inflammation is hypothesised to have some role. This study purported to evaluate the occurrence of anaemia in COPD and its association with inflammatory markers, erythropoietin levels, severity and exacerbations of COPD.

Methods Two hundred patients with COPD (90% men, mean age 62.4±8.33 years) were enrolled and subjected to detailed clinical and laboratory evaluation, including complete blood count, erythropoietin levels, C-reactive protein (CRP), pulmonary function test, blood gas analysis and chest X-ray. Severity of COPD was defined on the basis of forced expiratory volume in 1 s according to GOLD guidelines.

Results Anaemia was diagnosed in 14% of patients (n=28, predominantly normocytic normochromic type (92.8%)) and polycythmia in 5% of patients (n=10). The prevalence of anaemia increased with increasing severity of COPD (stage 2: 8%, stage 3: 14.4% and stage 4: 17.2%; p=0.46). Serum erythropoietin was significantly higher in more advanced COPD, with mean levels being 30.2±6.5, 31.78±8.09 and 39.33±7.68 mIU/mL in stage 2, 3 and 4 respectively. Moreover erythropoietin levels inversely correlated with mean haemoglobin levels(r=−0.25), indicating erythropoietin resistance. CRP reactivity increased with increasing stage of disease in patients with anaemia (p=0.026). On follow-up, significant inverse correlation was observed between haemoglobin and COPD exacerbations (p<0.001).

Conclusions Anaemia is a significant comorbidity of COPD with a negative prognostic impact on lung health. It can be ascribed to a state of systemic inflammation resulting in blunting of erythropoietin response with increasing severity of disease, leading to greater morbidity and hospitalisation.