Long-term oxygen therapy in COPD patients: population-based cohort study on mortality

Abstract

Nikolay Pavlov,1 Alan Gary Haynes,2,3 Armin Stucki,4 Peter Jüni,5 Sebastian Robert Ott1 1Department of Pulmonary Medicine, University Hospital (Inselspital), University of Bern, Bern, Switzerland; 2CTU Bern, University of Bern, Bern, Switzerland; 3Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland; 4Department of Internal Medicine, Spital Thun, Thun, Switzerland; 5Applied Health Research Centre, Li Ka Shing Knowledge Institute of St Michael’s Hospital, Department of Medicine, University of Toronto, Toronto, ON, Canada Purpose: Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide and is associated with a growing and substantial socioeconomic burden. Long-term oxygen therapy (LTOT), recommended by current treatment guidelines for COPD patients with severe chronic hypoxemia, has shown to reduce mortality in this population. The aim of our study was to assess the standardized mortality ratios of incident and prevalent LTOT users and to identify predictors of mortality. Patients and methods: We conducted a 2-year follow-up population-based cohort study comprising all COPD patients receiving LTOT in the canton of Bern, Switzerland. Comparing age- and sex-adjusted standardized mortality ratios, we examined associations between all-cause mortality and patient characteristics at baseline. To avoid immortal time bias, data for incident (receiving LTOT <6 months) and prevalent users were analyzed separately. Results: At baseline, 475 patients (20% incident users, n=93) were receiving LTOT because of COPD (48/100,000 inhabitants). Mortality of incident and prevalent LTOT users was 41% versus 27%, respectively, p<0.007, and standardized mortality ratios were 8.02 (95% CI: 5.64–11.41) versus 5.90 (95% CI: 4.79–7.25), respectively. Type 2 respiratory failure was associated with higher standardized mortality ratios among incident LTOT users (60.57, 95% CI: 11.82–310.45, p=0.038). Conclusion: Two-year mortality rate of COPD patients on incident LTOT was somewhat lower in our study than in older cohorts but remained high compared to the general population, especially in younger patients receiving LTOT <6 months. Type 2 respiratory failure was associated with mortality. Keywords: COPD, long-term oxygen therapy, mortality, type 2 respiratory failure

Keywords

• COPD
• long-term oxygen therapy
• mortality
• type 2 respiratory failure