Daily duration of long-term oxygen therapy and risk of hospitalization in oxygen-dependent COPD patients

Introduction: Long-term oxygen therapy (LTOT) improves survival and may reduce hospital admissions in patients with chronic obstructive pulmonary disease (COPD) and severe hypoxemia, but the impact of daily duration of LTOT on hospitalization rate is unknown. We aimed to estimate the association between the daily duration of LTOT (24 vs 15 h/d) and hospital admissions in patients with LTOT due to COPD. Materials and methods: A population-based, cohort study included patients who started LTOT due to COPD between October 1, 2005 and June 30, 2009 in the Swedish national register for respiratory failure (Swedevox). Time to first hospitalization from all causes and from respiratory or nonrespiratory disease, using the National Patient Registry, was analyzed using Fine-Gray regression, adjusting for potential confounders. Results: A total of 2,249 patients with COPD (59% women) were included. LTOT 24 h/d was prescribed to 539 (24%) and LTOT 15-16 h/d to 1,231 (55%) patients. During a median follow-up of 1.1 years (interquartile range, 0.6-2.1 years), 1,702 (76%) patients were hospitalized. No patient was lost to follow-up. The adjusted rate of all-cause hospitalization was similar between LTOT 24 and 15 16 h/d (subdistribution hazard ratio [SHR] 0.96; [95% CI] 0.84-1.08), as was cause-specific hospitalizations analyzed for respiratory disease (SHR: 1.00; 95% CI: 0.86-1.17) and nonrespiratory disease (SHR: 0.92; 95% CI: 0.75.-1.14). Conclusion: LTOT prescribed for 24 h/d was not associated with decreased hospitalization rates compared with LTOT for 15-16 h/d in patients with oxygen-dependent COPD. The results should be validated in a randomized controlled trial.