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

BACKGROUND: 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.

METHODS: 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.

RESULTS: A total of 494 patients 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 3 months, 19.6% of the initial cohort had oxygen discontinued. In those subjects with oxygen continued at 3 months, COPD was the most common diagnosis (63.6%), of which 76.1% had pulmonary function tests (PFTs), with 85.7% showing obstruction on spirometry.

CONCLUSIONS: 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 3 months 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.