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Abstract
Previous studies sought to identify survival or outcome predictors in patients with COPD and chronic respiratory failure, but their findings are inconsistent. We identified mortality-associated factors in a prospective study in 21 centers in 7 countries. Follow-up data were available in 221 patients on home mechanical ventilation and/or long-term oxygen therapy. Measurements: diagnosis, co-morbidities, medication, oxygen therapy, mechanical ventilation, pulmonary function, arterial blood gases, exercise performance were recorded. Health status was assessed using the COPD-specific SGRQ and the respiratory-failure-specific MRF26 questionnaires. Date and cause of death were recorded in those who died.
Overall mortality was 19.5%. The commonest causes of death were related to the underlying respiratory diseases. At baseline, patients who subsequently died were older than survivors (p = 0.03), had a lower forced vital capacity (p = 0.03), a higher use of oxygen at rest (p = 0.003) and a worse health status (SGRQ and MRF26, both p = 0.02). Longitudinal analyses over a follow-up period of 3 years showed higher median survival times in patients with use of oxygen at rest less than 1.75 l/min and with a better health status. In contrast, an increase from baseline levels of 1 liter in O2 flow at rest, 1 unit in SGRQ or MRF26, or 1 year increase in age resulted in an increase of mortality of 68%, 2.4%, 1.3%, and 6%, respectively. In conclusion, the need for oxygen at rest, and health status assessment seems to be the strongest predictors of mortality in COPD patients with chronic respiratory failure.
Acknowledgments
The authors are grateful to Dr. Richard Zuwallack and Dr. Jean Bourbeau for helpful suggestions in the study design. The authors also are grateful to Dr. Francesco Giuseppe Salerno for revising the paper and helping in the submission process.
Funding
Grant Support: This work is from the Quality of Life Evaluation and Survival Study (QuESS) Group. QuESS group meetings and database management (Dr. Antoniu) were made possible thanks to a grant from Boehringer Ingelheim International GmbH (n. 927811/001/2001). Dr. Antoniu was also supported by a research fellowship awarded by the European Respiratory Society in 2001.
Declaration of Interest Statement
None of the authors had involvement in any organization with direct financial interest in the subject of the manuscript.
Mauro Carone, conceived and designed the project and wrote the paper; Sabina Antoniu, partly analyzed and interpreted the data, partly wrote the paper and revised it;
Paola Baiardi, performed statistical managing and analyzed the data, and partly wrote the paper; Vincenzo S. Digilio, partly interpreted the data, wrote the paper and revised it; Paul Wyatt Jones, conceived, designed and supervised the project, partly wrote the paper and revised it; Giorgio Bertolotti, conceived and designed the project, partly wrote the paper and revised it.
Figures 1-4
Survival curves of patients with chronic respiratory failure stratified for age; Oxygen flow at rest, SGRQ total score, and MRF26 total score. “More impaired” and “less impaired” subgroups were identified according to cut-off points of the ROC analysis. “More impaired” patients (dashed lines) presented a higher mortality than “less impaired” patients (continuous lines) for all the showed parameters. P-values were calculated using the Log-Rank test.