A Retrospective Observational Study of Domiciliary Oxygen Usage in a Subset of Veterans.

Abstract

Long-term oxygen therapy (LTOT) delivered continuously is known to decrease mortality in patients with COPD and who are hypoxemic; however, supportive data for LTOT use in patients without COPD is lacking. In addition, many patients may be prescribed LTOT without a definitive etiology for hypoxemia. First, we investigated the diagnoses for which oxygen was prescribed to a sample of veterans and whether each diagnosis was supported by confirmatory testing. Second, we looked at the proportion of subjects who were prescribed non-continuous therapy. We retrospectively studied subjects prescribed domiciliary oxygen at the Veterans Administration Western New York Healthcare System. The subjects who met inclusion criteria were identified by using a computerized patient record system; data were collected on subject characteristics, oxygen prescription information, diagnosis for hypoxia, and diagnostic workup. Descriptive data were presented as mean ± SD and median (range). Statistical analysis was performed by using the chi-square test and an unpaired t test. A total of 494 subjects were included: 96.8% men, mean ± SD ages 74.2 ± 10.8 y. Most of the subjects were prescribed oxygen as out-patients (68.5%). A total of 335 (67.8%) were prescribed oxygen for continuous therapy, 72 (14.1%) for nocturnal therapy, 50 (10.1%) for exertion, and 30 (6.1%) for both exertion and nocturnal use. At 3months, 19.6% of the initial cohort had oxygen discontinued. In those subjects with oxygen continued at 3months, COPD was the most common diagnosis (63.6%), of which 76.1% had pulmonary function tests (PFTs), with 85.7% showing obstruction on spirometry. Results of our study showed a 99.4% adherence to Medicare criteria for domiciliary oxygen prescription. Also, 30.3% of the subjects were prescribed LTOT for exertional or nocturnal desaturation or both. Repeated testing at 3months identified subjects who no longer required oxygen. COPD was the most common etiology for domiciliary oxygen. A small proportion of the subjects (6.9%) were prescribed oxygen without underlying etiology for hypoxia. Exertional and/or nocturnal oxygen prescription was common, and further research to elucidate its utility is clearly warranted.