CAT-score is a predictor for mortality in COPD

Abstract

Background: CAT (COPD Assessment Test) is a validated 8-item questionnaire designed to evaluate symptoms in COPD patients. Our study aimed to evaluate COPD symptoms as a marker for mortality, measured in total CAT-score as well as individual symptom scores.
Methods: We included 285 patients with an established COPD diagnosis, admitted with COPD-exacerbation to several hospitals in Western Norway, using data from the Norwegian COPD Registry. All patients completed a CAT questionnaire before discharge, in addition, the patients performed a spirometry, arterial blood gas sampling, and had their BMI and co-morbidities evaluated. The patients were followed for up to 5 years. Mortality was evaluated using cox-regression, adjusting for sex, age, FEV1, BMI and blood gas analysis (hyperkapnia).
Results: 118 of 285 patients died within follow up. Median CAT score at discharge was 24 of maximum 40 points. Increasing CAT score was significantly associated with higher mortality, HR 1.02 (1.01-1.04, p<0.01) for one point increase, or 1.24 (1.05-1.37, p<0.01) for 8 point (one fifth) increase, adjusted values. For the individual symptoms, breathlessness at stair walking, HR 1.31 (1.06-1.63, p<0.01) or domestic activity limitations, HR 1.35 (1.11-1.65, p<0.01) for 1 point (one fifth) increase, were both significantly associated with higher mortality (adjusted values). Other factors significantly associated with mortality were age, male sex, FEV1<30% of predicted, three or more comorbidities and hypercapnia.
Conclusion: Increasing CAT score is associated with higher mortality, however, simply asking about breathlessness at stair walking or domestic activity limitations may give a better indication of mortality risk.