Feature Article

COPD Comorbidities Can Identify Mortality Risk

Using data from a cohort of 1,664 patients with COPD, researchers identified 12 comorbidities that increase mortality risk in this population and constructed a new index for predicting this risk.

Twelve comorbidities have a negative impact on mortality in patients with COPD, researchers reported in the July 15 American Journal of Respiratory and Critical Care Medicine. They also described their construction and testing of a new index for predicting COPD mortality by assigning points to comorbidities.

Miguel Divo, MD, of Brigham and Women’s Hospital, Boston, and colleagues investigated a cohort of 1,664 patients with COPD enrolled in an ongoing study from five centers in the US and Spain. The patients were followed for a median of 51 months, during which they received examinations at least every year. Comorbidities were recorded through direct questioning and confirmed via medication lists and medical records. Cause-specific mortality was ascertained by each site investigator.

Core of Diseases
The patients had a total of 79 comorbidities, 15 of which differed in prevalence between survivors and nonsurvivors. Of those comorbidities, 12 predicted mortality: lung cancer, pancreatic cancer, esophageal cancer, breast cancer, pulmonary fibrosis, atrial fibrillation/flutter, congestive heart failure, coronary artery disease, gastric/duodenal ulcers, liver cirrhosis, diabetes with neuropathy, and anxiety.

These comorbidities are easily identifiable and “could form the core of diseases that could be screened by healthcare providers caring for these patients, because for some of them there are effective interventions that may help decrease the risk of death,” the researchers suggested.

They expressed the prevalence and mortality risk of COPD comorbidities through a graphic chart called the “cormorbidome.” The chart represents each comorbidity as an orbital bubble, with a diameter proportional to its prevalence and its distance from the chart’s center inversely proportional to its mortality hazard.

The COTE Index
Divo and colleagues also used their data to create the COTE (COPD Specific Comorbidity Test) index, which assigns points ranging from 1 to 6 (indicating the highest hazard ratios [HRs]) to each comorbidity. Six points were assigned to lung, esophageal, pancreatic, and breast cancer and anxiety; 2 points were assigned to liver cirrhosis, atrial fibrillation/flutter, diabetes with neuropathy, and pulmonary fibrosis; and 1 point was assigned to congestive heart failure, gastric/duodenal ulcers, and coronary artery disease.

In testing the COTE, the investigators found that for each 1-point increase, patients’ HR for death increased by 1.14. COTE increases were associated with higher risk of death both from COPD-related and non–COPD related causes, with HRs of 1.13 and 1.18, respectively. In addition, COTE added to the predictive value of the validated BODE (BMI, airflow obstruction [FEV1], dyspnea, and exercise capacity) index.

“A combination of BODE and the COTE index provides healthcare workers and researchers with simple tools to better stratify patients and provides a platform for comparative effectiveness research,” the investigators concluded.

—Jack Baney

Suggested Reading
Divo M, Cote C, de Torres JP, et al; the BODE Collaborative Group. Comorbidities and risk of mortality in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 2012;186(2):155-161.

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