Published ahead of print on June 5, 2008, doi:10.1164/rccm.200709-1383OC Am. J. Respir. Crit. Care Med., Volume 178, Number 5, September 2008, 491-499 A more recent version of this article appeared on September 1, 2008
Submitted on September 18, 2007 Longitudinal Change in the BODE Index Predicts Mortality in Severe EmphysemaFernando J Martinez1*,1 Division of Pulmonary and Critical Care Medicine, University of Michigan Medical Center, Ann Arbor, MI, United States, 2 Department of Biostatistics and Medical Informatics, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA, 3 Division of Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, USA, 4 Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, MI, USA, 5 Division of Pulmonary and Critical Care Medicine, University of Michigan Medical Center, Ann Arbor, MI, United States; Pulmonary Section, Ann Arbor VAMC, Ann Arbor, MI, USA, 6 Pulmonary and Critical Care Medicine, Temple University, Philadelphia, PA, USA, 7 Division of Pulmonary Medicine, Brigham and Women's Hospital, Boston, MA, USA, 8 Division of Pulmonary and Critical Care Medicine, National Jewish Medical and Research Center, Denver, CO, USA, 9 Department of Medicine, University of California, San Diego, CA, USA, 10 Division of Pulmonary and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, USA, 11 Division of Lung Diseases, National Heart, Lung and Blood Institute, Bethesda, MD, USA, 12 Division of Pulmonary Medicine, Cedars Sinai Medical Center, Los Angeles, CA, USA, 13 Section of Thoracic Surgery, Beth Israel Deaconess Medical Center, Boston, MA, USA, 14 Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA, 15 Pulmonary, Critical Care and Sleep Medicine Division, St. Elizabeth's Medical Center, Boston, MA, USA * To whom correspondence should be addressed. E-mail: fmartine{at}med.umich.edu.
Background: The predictive value of longitudinal change in BODE has received limited attention. We hypothesized that decrease in a modified BODE (mBODE) would predict survival in National Emphysema Treatment Trial (NETT) patients. Methods: Clinical data were recorded using standardized instruments. mBODE was calculated and patient-specific mBODE trajectories during 6, 12 and 24 months of follow-up were estimated using separate regressions for each patient. Patients were classified as having decreasing, stable, increasing or missing mBODE based on their absolute change from baseline. The predictive ability of mBODE change on survival was assessed using multivariate Cox regression models. The index of concordance was used to directly compare the predictive ability of mBODE and its separate components. Results: The entire cohort (610 treated medically and 608 treated surgically) was characterized by severe airflow obstruction, moderate breathlessness and increased mBODE at baseline. A wide distribution of change in mBODE was seen at follow-up. An increase in mBODE > 1 point was associated with increased mortality in surgically and medically treated patients. Surgically treated patients were less likely to experience death or an increase > 1 in mBODE. Indices of concordance showed that mBODE change predicted survival better than its separate components. Conclusion: mBODE demonstrates short and intermediate term responsiveness to intervention in severe COPD. Increase in mBODE > 1 point from baseline to 6, 12 and 24 months of follow-up was predictive of subsequent mortality. Change in mBODE may prove a good surrogate measure of survival in therapeutic trials in severe COPD. Clinical trial registration available at: www.clinicaltrials.gov, identifier code = NCT00000606 Key words: COPD, survival, multidimensional index
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