Role of Anemia in Home Oxygen Therapy in Chronic Obstructive Pulmonary Disease Patients

Abstract

Anemia is a known comorbidity found in chronic obstructive pulmonary disease (COPD) patients. Hypoxemia is common and basically due to ventilation/perfusion (V/Q) mismatch in COPD. Anemia, by decreasing arterial oxygen content, may be a contributing factor for decreased delivery of oxygen to tissues. The objective of this study is to determine if anemia is a factor in qualifying COPD patients for home oxygen therapy. The study was designed as a retrospective, cross-sectional, observational chart review. Patients who were referred for home oxygen therapy evaluation were selected from the computerized patient record system. Demographic data, oxygen saturation at rest and during exercise, pulmonary function test results, hemoglobin level, medications, reason for anemia, comorbid diseases, and smoking status were recorded. The χ tests, independent sample t tests, and logistic regression were used for statistical analysis. Only 356 of total 478 patient referrals had a diagnosis of COPD over a 2-year period. Although 39 of them were excluded, 317 patients were included in the study. The overall rate of anemia was 38% in all COPD patients. Anemia was found significantly more frequent in COPD patients on home oxygen therapy (46%) than those not on home oxygen therapy (18.5%) (P < 0.0001). Mean saturation of peripheral oxygen values were significantly lower in anemic COPD patients both at rest and during exercise (P < 0.0001). Also, in COPD patients, age, Global Initiative for Chronic Obstructive Lung Disease class, smoking status, hemoglobin level, hematocrit, percent of forced expiratory volume in first second, forced expiratory volume in first second/forced vital capacity, residual volume/total lung volume, percent of carbon monoxide diffusion capacity were significantly different between home oxygen therapy and those not on home oxygen therapy (P < 0.05). Multivariate logistic regression showed that anemia remained a strong predictor for long-term oxygen therapy use in COPD patients after adjusting for other significant parameters. Anemic COPD patients are more hypoxic especially during exercise than those who are not anemic. We conclude that anemia is a contributing factor in qualifying COPD patients for home oxygen therapy.

Comorbidities and Chronic Obstructive Pulmonary Disease: Prevalence, Influence on Outcomes, and Management

“…76 Additionally, anemia has been described as a risk factor for long-term oxygen use in patients with COPD. 77 One group of investigators noted a higher risk for dyspnea in COPD patients with concomitant anemia. Additionally, they found alterations in exercise testing measures in these individuals as well as a lower anaerobic threshold, demonstrating lower circulatory efficiency during exercise in COPD patients with anemia.…”

Anaemia in chronic obstructive pulmonary disease: an insight into its prevalence and pathophysiology

“…According to current World Health Organization (WHO), anaemia in the general population is defined by Hb levels <13 g/dl in male and <12 g/dl in female [25] and these thresholds have been used by several authors in order to identify anaemic COPD patients [5,8,11,15,26]. However, the use of a Hb <12 g/dl threshold to define anaemia in postmenopausal women is currently under debate [27], so the 13 g/dl threshold for both male and female has also been applied [2,4,7,19]. Controversy is even more evident regarding COPD patients admitted in the ICU, since there is as yet no accepted definition of abnormal Hb values in the critically ill [18].…”

“…Boutou [8] [2,4,[7][8][9]14,21], several have applied the ICD 9/10 codes [13,[22][23][24] or identified COPD patients from existing databases without describing the diagnostic criteria in detail [19]. Thus, it is possible that in these studies, patients with respiratory symptoms of airflow obstruction without fulfilling spirometric criteria for COPD were misclassified, creating more variation regarding anaemia prevalence.…”

<p>Management of the COPD Patient with Comorbidities: An Experts Recommendation Document</p>

“…245 In addition, the presence of anemia in COPD is associated with a lower exercise tolerance, 243 greater dyspnea, 246 higher C-reactive protein values, 241 and greater use of healthcare resources. 243 It is also a risk factor for home oxygen therapy in these patients, 250 ( Supplementary Table 5B). Anemia is a modifiable condition and correction of anemia in chronic diseases other than the COPD has been associated with improved health.…”