Body weight and comorbidity predict mortality in COPD patients treated with oxygen therapy

The aim of this study was to investigate the association between clinical variables and all-cause and respiratory mortality in patients with chronic obstructive pulmonary disease (COPD) undergoing long-term oxygen therapy (LTOT). The authors retrospectively studied a historic cohort of 128 patients with COPD (126 males, mean age +/- SD 68.9 +/- 9.7 yrs, body mass index (BMI) 25.1 +/- 4.5 kg(.)m(-2), and forced expiratory volume in one second 25.4 +/- 8.8% predicted), who were being treated with long-term oxygen therapy in a tertiary teaching hospital between 1992 and 1999. Comorbidity, assessed with the Charlson Index, was present in 38% of the patients. Vital status and cause of death were assessed through the population death registry. A total of 78 patients (61%) had died by the end of follow-up. Three-year survival was 55%. Death was due to respiratory causes in 77% of cases. On Cox analysis, BMI < 25 kg(.)m(-2), comorbid conditions, age >= 70 yrs and cor pulmonale were associated with all-cause mortality. The BMI and comorbidity were the only significant predictive factors when the analysis was restricted to respiratory mortality. In conclusion, body mass index < 25 kg(.)m(-2) and comorbidity were predictors of all-cause and respiratory mortality in a cohort of chronic obstructive pulmonary disease patients treated with long-term oxygen therapy. These factors should be taken into account when considering the management and prognosis of these patients.