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

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. This prospective observational study aimed to identify the predictors of two-year mortality in patients receiving long-term oxygen therapy. 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. 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. 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;  < 0.01; Wald: 14.38.), mMRC (adjusted HR: 1.96; 95% CI: 1.36-2.83;  < 0.01; Wald: 13.16.), BI (adjusted HR: 0.95; 95% CI: 0.93-0.98;  < 0.01; Wald: 17.07.), and MoCA (adjusted HR: 2.17; 95% CI: 1.31-3.59;  < 0.01; Wald: 9.06) as predictors. 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.