Home oxygen therapy reduces risk of hospitalisation in patients with chronic obstructive pulmonary disease: a population-based retrospective cohort study, 2005-2012

Objective: This study evaluated the effect of home oxygen therapy (HOT) on hospital admissions in chronic obstructive pulmonary disease (COPD) patients. Design and setting: Using nationwide health insurance claims from 2002-2012, we conducted a longitudinal population-based retrospective cohort study. Participants: Individuals who were aged 40 years or above and newly diagnosed with COPD in 2005. Outcome measures: The primary outcome was total number of hospitalisations during the study period. Participants were matched using HOT propensity scores and were stratified by respiratory impairment (grade 1: FEV₁ ≤25% or PaO₂ ≤55 mm Hg; grade 2: FEV₁ ≤30% or PaO₂ 56-60 mm Hg; grade 3: FEV₁ ≤40% or PaO₂ 61-65 mm Hg; 'no grade': FEV₁ or PaO₂ unknown), then a negative binomial regression analysis was performed for each group. Results: Of the 36 761 COPD patients included in our study, 1330 (3.6%) received HOT. In a multivariate analysis of grade 1 patients performed before propensity score matching, the adjusted relative risk of hospitalisation for patients who did not receive HOT was 1.27 (95% CI 1.01 to 1.60). In a multivariate analysis of grade 1 patients performed after matching, the adjusted relative risk for patients who did not receive HOT was 1.65 (95% CI 1.25 to 2.18). In grade 2 or grade 3 patients, no statistical difference in hospital admission risk was detected. In the 'no grade' group of patients, HOT was associated with an increased risk of hospitalisation. Conclusions: HOT reduces the risk of hospital admission in COPD patients with severe hypoxaemia. However, apart from these patients, HOT use is not associated with hospital admissions.