Predictors of 2-Year Mortality in Patients Receiving Long-Term Oxygen Therapy: A Prospective Observational Study

Background: Patients receiving long-term oxygen therapy are in a state of progressive respiratory dysfunction and have high mortality. However, the predictors of mortality in these patients have not yet been established. Objectives: This prospective observational study aimed to identify the predictors of two-year mortality in patients receiving long-term oxygen therapy. Design, Setting/Subjects: This two-year prospective observational study included 96 patients who received long-term oxygen therapy in the outpatient department of the National Hospital Organization Nishiniigata Chuo Hospital in Japan. Measurements: The updated Charlson Comorbidity Index, body mass index, handgrip strength, modified British Medical Research Council scale (mMRC), Barthel Index (BI), and Montreal Cognitive Assessment (MoCA) were collected in 2019 as a baseline. Outcome was defined as mortality due to chronic respiratory disease during the two-year follow-up period, and predictors were estimated using age- and sex-adjusted Cox proportional hazards model. Results: The 83 patients that were followed up, 30 (36%) died. The Cox proportional hazards model estimated handgrip strength (adjusted hazard ratio [HR]: 0.89; 95% confidence interval [CI]: 0.84-0.94; p < 0.01; Wald: 14.38.), mMRC (adjusted HR: 1.96; 95% CI: 1.36-2.83; p < 0.01; Wald: 13.16.), BI (adjusted HR: 0.95; 95% CI: 0.93-0.98; p < 0.01; Wald: 17.07.), and MoCA (adjusted HR: 2.17; 95% CI: 1.31-3.59; p < 0.01; Wald: 9.06) as predictors. Conclusions: This study indicated that handgrip strength, dyspnea, activities of daily living, and cognitive function were predictors of two-year mortality in patients receiving long-term oxygen therapy.