The CANT score: Predicting mortality in exacerbations of chronic obstructive pulmonary disease

Abstract

Introduction: Biomarkers of cardiac dysfunction are often high in exacerbations of COPD and are associated with mortality. They have the potential to improve the assessment of prognosis for patients with COPD exacerbations. Aims: To derive and validate an exacerbation severity score that includes clinical indicators, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and troponin T. Methods: The derivation (n=247) and validation (n=176) cohorts included consecutive patients hospitalised for an exacerbation of COPD over different years. Logistic regression was used to identify predictors of 30-day mortality in the derivation cohort including CURB65 (confusion, urea >7mmol/L, respiratory rate ≥30/min, hypotension, age ≥65 years), BAP65 (urea >9mmol/L, confusion, tachycardia, age >65 years), acidaemia (pH 220pmol/L) and troponin T (>0.03μg/L). The area under the receiver operating curve (AUC) analysis was used to compare the new composite score with CURB65 and BAP65 alone. Results: 30-day mortality in the derivation and validation cohorts was 9% and 6%, respectively. CURB65, BAP65, acidaemia, high NT-proBNP, and high troponin T predicted mortality in the derivation cohort. The derived CANT score included one point for each of: high CURB-65 score (>2), acidaemia, high NT-proBNP, and high troponin T. The CANT score was better than either CURB65 or BAP65 in predicting mortality in both the derivation cohort (AUC 0.855, 0.723 and 0.635, respectively) and the validation cohort (AUC 0.824, 0.693 and 0.723, respectively). Conclusion: Assessing the prognosis of COPD exacerbations can be improved by including cardiac biomarkers.