Anemia of Chronic Disease in Chronic Obstructive Pulmonary Disease: A Case-Control Study of Cardiopulmonary Exercise Responses

Background: Anemia may be present in patients with chronic obstructive pulmonary disease (COPD) and further impair their functional capacity. Objectives: This study investigated the prevalence of anemia of chronic disease (ACD) in COPD patients and its impact on dyspnea and exercise capacity, utilizing cardiopulmonary exercise testing (CPET). Methods: ACD prevalence was assessed in 283 consecutive patients with stable COPD (263 males, 60 females; age 60.31 +/- 5.34 years; percent forced expiratory volume in 1 s 46.94 +/- 6.12). ACD diagnosis was based on a combination of clinical and laboratory parameters [hemoglobin (Hb) < 13 g/dl for males, < 12 g/dl for females; ferritin > 30 ng/ml; total iron-binding capacity < 250 mu g/dl, and transferrin saturation rate between 15 and 50%]. Twenty-seven patients who were identified with ACD (cases) and 27 matched nonanemic patients (controls) completed maximal CPET, and data were compared between the groups. Results: ACD was diagnosed in 29 patients, which represents a prevalence of 10.24%; the severity ;of anemia was generally mild (mean Hb: 12.19 +/- 0.66 g/dl). Patients with ACD had a higher Medical Research Council dyspnea score compared to controls (2.78 +/- 0.44 vs. 2.07 +/- 0.55; p < 0.001) and lower peak O-2 uptake (VO2) (59.54 +/- 17.17 vs. 71.26 +/- 11.85% predicted; p < 0.05), peak work rate (54.94 +/- 21.42 vs. 68.72 +/- 20.81% predicted; p < 0.05) and peak VO2/heart rate (69.07 +/- 17.26 vs. 82.04 +/- 18.22% predicted; p ! 0.05). There was also a trend for a lower anaerobic threshold (48.48 +/- 15.16 vs. 55.42 +/- 9.99% predicted; p = 0.062). No exercise parameter indicative of respiratory limitation differed between the groups. Conclusions: ACD occurs in approximately 10% of stable COPD patients and has a negative impact on dyspnea and circulatory efficiency during exercise. Copyright (C) 2011 S. Karger AG, Basel