Patients receiving longterm oxygen therapy (LTOT) frequently experience severe breathlessness and impaired exercise performance, both factors that are linked with worse outcomes in interstitial lung disease (ILD) and COPD, according to Filip Björklund and colleagues.
Although methods exist for evaluating these factors and managing their effect on patients, no study has evaluated the predictive ability of breathlessness or exercise performance for mortality in patients with LTOT. “Identifying these predictors is critical,” the study authors wrote, “as it could help clinicians identify vulnerable patients in need of optimized management, such as identification and treatment of comorbidities, pulmonary rehabilitation, and intensified follow-up.”
Breathlessness Initially Associated With Mortality
For a study published in Respiratory Medicine, Björklund and colleagues sought to evaluate exercise performance and breathlessness at the initiation of LTOT as predictors of short-term and overall mortality. The researchers conducted a longitudinal, population-based study of patients who started LTOT between 2015 and 2018. The Dyspnea Exertion Scale was used to measure breathlessness and the 30s-Sit-To-Stand (30s-STS) test was used to assess exercise performance. Associations between exercise performance, breathlessness, and mortality were analyzed via Kaplan-Meier curves and crude and multivariable (Figure); Cox regression was used to assess the correlations between 3-month and overall mortality. For patients with COPD and ILD, subgroup analyses were performed, respectively.
A total of 441 patients (57.6% female, aged 75.4±8.3) were analyzed, of whom 32% died during a median follow-up of 260 days (interquartile range, 75-460). In the crude model, the study team observed that both breathlessness and exercise performance were independently linked with overall mortality, but only exercise performance remained independently linked with overall mortality when short-term mortality was analyzed, when models were adjusted for other predictors, or when breathlessness and exercise capacity were evaluated concurrently. The multivariable model including exercise performance, but not breathlessness, offered a relatively high predictive capacity for overall mortality (C-statistic, 0.756; 95% CI, 0.702-0.810).
Exercise performance and breathlessness at the initiation of LTOT as predictors of short-term and overall mortality.
The researchers conducted a longitudinal, population-based study of patients who started LTOT between 2015 and 2018. The Dyspnea Exertion Scale was used to measure breathlessness and the 30s-Sit-To-Stand (30s-STS) test was used to assess exercise performance. Associations between exercise performance, breathlessness, and mortality
were analyzed via Kaplan-Meier curves and crude and multivariable (Figure); Cox regression was used to assess the correlations between 3-month and overall mortality. For patients with COPD and ILD, subgroup analyses were performed, respectively.
A total of 441 patients (57.6% female, aged 75.4±8.3) were analyzed, of whom 32% died during a median follow-up of 260 days (interquartile range, 75-460). In the crude model, the
study team observed that both breathlessness and exercise performance were independently linked with overall mortality, but only exercise performance remained independently linked with overall mortality when short-term mortality was analyzed, when models were adjusted for other predictors, or when breathlessness and exercise capacity were evaluated concurrently. The multivariable model including exercise performance, but not breathlessness, offered a relatively high predictive capacity for overall mortality (C-statistic, 0.756; 95% CI, 0.702-0.810).
