Short- and Medium-term Prognosis in Patients Hospitalized for COPD Exacerbation The CODEX Index

Background: No valid tools exist for evaluating the prognosis in the short and medium term after hospital discharge of patients with COPD. Our hypothesis was that a new index based on the CODEX (comorbidity, obstruction, dyspnea, and previous severe exacerbations) index can accurately predict mortality, hospital readmission, and their combination for the period from 3 months to 1 year after discharge in patients hospitalized for COPD. Methods: A multicenter study of patients hospitalized for COPD exacerbations was used to develop the CODEX index, and a different patient cohort was used for validation. Comorbidity was measured using the age-adjusted Charlson index, whereas dyspnea, obstruction, and severe exacerbations were calculated according to BODEX (BMI, airflow obstruction, dyspnea, and previous severe exacerbations) thresholds. Information about mortality and readmissions for COPD or other causes was collected at 3 and 12 months after hospital discharge. Results: Two sets of 606 and 377 patients were included in the development and validation cohorts, respectively. The CODEX index was associated with mortality at 3 months (P<.0001; hazard ratio [HR], 1.5; 95% CI, 1.2-1.8) and 1 year (P<.0001; HR, 1.3; 95% CI, 1.2-1.5), hospital readmissions in the same periods, and their combination (all P<.0001). All CODEX C statistics were superior to those of the BODEX, DOSE (dyspnea, airflow obstruction, smoking status, and exacerbation frequency), and updated ADO (age, dyspnea, and airflow obstruction) indexes. Conclusions: The CODEX index was a useful predictor of survival and readmission at both 3 months and 1 year after hospital discharge for a COPD exacerbation, with a prognostic capacity superior to other previously published indexes.