Baseline characteristics of patients starting long-term oxygen therapy for chronic obstrucitve pulmonary disease, 1992–2008.

Data presented as mean ± SD unless otherwise specified.
Definition of abbreviations: FEV1 = forced expiratory volume in one second; FVC = forced vital capacity; PaCO2 air = arterial blood gas tension of carbon dioxide while breathing ambient air; PaCO2 oxygen = arterial blood gas tension of carbon dioxide while breathing oxygen; PaO2 air = arterial blood gas tension of oxygen while breathing ambient air; PaO2 oxygen = arterial blood gas tension of oxygen while breathing oxygen.
*Hospitalizations and in-hospital days within 5 years prior to starting LTOT, presented as median (first quartile – third quartile).