Abstract
BACKGROUND: Supplemental oxygen therapy is commonly prescribed in clinical practice for patients with fibrosing interstitial lung disease (ILD) to reduce breathlessness and increase physical capacity. Only a few studies have evaluated the incidence of oxygen therapy use, with evidence lacking in its use among fibrosing ILD subtypes including patients with idiopathic pulmonary fibrosis (IPF) and non-IPF ILD. This study aimed to estimate incidence of oxygen therapy and factors associated with oxygen therapy initiation. METHODS: This non-interventional study used US administrative claims and electronic health record data from 01 October 2015 to 30 June 2022. Patients aged ≥ 18 years with newly diagnosed fibrosing ILD (≥ 2 fibrosing ILD diagnoses in any position on different dates of service within 365 days) were included; the index date was the first date with ILD diagnosis. Patients were followed until the earlier of health plan disenrollment, death, or end of study period. Oxygen therapy use was evaluated among patients without evidence of oxygen therapy before the index date, stratified by the underlying fibrosing disease (i.e., IPF vs. non-IPF ILD). Factors associated with oxygen therapy use were evaluated using Cox proportional hazards regression. RESULTS: A total of 114,921 patients (IPF n = 5,555; non-IPF ILD n = 109,366) newly diagnosed with fibrosing ILD were included in the study. The mean (standard deviation) age of patients with ILD was 66.9 (14.2) years, and 47.2% were male. Patients were followed for a mean of 24 months after ILD diagnosis, during which 38% of fibrosing ILD patients initiated oxygen therapy; a higher proportion of patients with IPF initiated oxygen therapy compared to those with non-IPF ILD (68% and 36%, respectively). Factors associated with oxygen therapy initiation included IPF, higher Charlson comorbidity scores, and comorbidities that impair respiratory capacity. CONCLUSIONS: The study findings demonstrate a substantial proportion of patients with fibrosing ILD initiated oxygen therapy following initial ILD diagnosis, with higher rates of oxygen therapy initiation observed among patients with IPF compared with non-IPF ILD. Respiratory comorbidities were key factors associated with increased initiation of oxygen therapy.