Abstract
Comorbidities influence outcome in COPD, but, their role remains poorly described. We studied the impact on survival of COPD related comorbidities and developed a COPD specific comorbidity (COTE) index. We also compared COTE with the Charlson Comorbidity Index (CCI) and BODE.
Methods: We followed 1664 COPD subjects for over 4 years. Systematically, 80 possible comorbidities were recorded including conditions listed in CCI. In a randomly selected 2/3 of the cohort we calculated their prevalence. Using Cox proportional hazard, 6 of these comorbidities were independently associated with mortality. We then assigned points to the 6 comorbidities and constructed the COTE index based on likelihood ratios for death.
The COTE index was then validated in the rest (1/3) of the cohort. Finally, we compared the value of COTE,Charlson and BODE index to predict mortality in the whole population.
Results: 23 of 80 comorbidities differed in prevalence between survivors and non-survivors. The COTE index was superior to Charlson in mortality prediction: HR (95%CI) of [1.22 (1.17,1.27, p<0.001) vs 1.03 (0.99,1.07, p =0.126)] and complementary to BODE [1.32 (1.28,1.36, p < 0.001)].
Conclusion: Comorbidities are prevalent in COPD and a subset of them influences survival. The COTE is simpler and more accurate than the Charlson index to predict survival. The COTE also adds independent predictive power to the BODE index.
- © 2011 ERS