Comparison of baseline characteristics of Medicare beneficiaries on Oxygen Therapy with Chronic Obstructive Pulmonary Disease (COPD) 1, 2001–2010.

1. A Chronic Obstructive Pulmonary Disease (COPD) diagnosis is defined as having International Classification of Diseases, ninth revision (ICD-9) codes 491.x [chronic bronchitis], 492.x [emphysema], or 496 [chronic airway obstruction].2. Sustained oxygen use is defined as ≥11 claims for oxygen therapy during the calendar year3. Socioeconomic status: based on whether the patient was eligible for state buy-in coverage provided by the Medicaid program for at least one month during the index year;4. Region: Geographic region was divided into 9 CMS regions;5. Elixhauser comorbidity components: chronic pulmonary disease, congestive heart failure, valvular disease, pulmonary circulation disorders, peripheral vascular disorders, hypertension, paralysis, other neurological disorders, diabetes-uncomplicated, diabetes-complicated, hypothyroidism, renal failure, liver disease, peptic ulcer disease excluding bleeding, AIDS (acquired immune deficiency syndrome), lymphoma, metastatic cancer, solid tumor without metastasis, rheumatoid arthritis/collagen vascular diseases, coagulopathy, obesity, weight loss, fluid and electrolyte disorders, blood loss anemia, deficiency anemia, alcohol abuse, drug abuse, psychoses, and depression[11].Comparison of baseline characteristics of Medicare beneficiaries on Oxygen Therapy with Chronic Obstructive Pulmonary Disease (COPD) 1, 2001–2010.