CAT score useful for predicting COPD exacerbations

Sep 3 2014

By Laura Cowen, medwireNews Reporter

The likelihood and imminence of a chronic obstructive pulmonary disease (COPD) exacerbation in high-risk patients could be predicted using the COPD assessment test (CAT) score, study findings indicate.

Using this test “may allow better informed decisions in the clinical management of COPD patients and improve health resource allocation”, write Dimitar Sajkov (Flinders Medical Centre, Adelaide, Australia) and colleagues in Respiratory Medicine.

A total of 495 patients (mean age 69 years, 88% men) from 19 clinics in Australia, China, Korea and Taiwan completed the CAT as part of the study. The patients, who all had a history of exacerbations in the preceding year, had a mean CAT score of 14.8; 27.1% had a score of 0–9, 47.7% had a score of 10–19, 21.0% had a score of 20–29 and 4.2% had a score of 30–40.

During the 6-month study period, 68% of patients experienced at least one COPD exacerbation of any severity and 46% had a moderate-to-severe exacerbation.

The incidence of exacerbations increased with increasing CAT score category, from 52% in patients with a score of 0–9 at baseline to 71%, 80% and 100% in those with scores of 10–19, 20–29 and 30–40, respectively.

An unadjusted area under the receiver operating characteristic curve (AUC) of 0.83 indicated that the categorised CAT score accurately predicted time to first exacerbation. Indeed, the median time to exacerbation was just 5 weeks for patients with a score of 30–40 compared with more than 24 weeks for those with a score of 0–9.

The categorised CAT score also had a modest predictive value for any exacerbation and moderate-to-severe exacerbations, with respective unadjusted AUCs of 0.64 and 0.63.

However, Sajkov and team point out that a “similar level of predictive ability for COPD exacerbation (AUC 0.62–0.69) was reported in other studies where the prediction models consisted of a combination of risk factors, which may not be practical to use in clinical practice.”

They therefore say that their findings “support the use of the CAT as a convenient and reliable alternative to these models to achieve the same level of prediction for exacerbations.”

Furthermore, higher CAT scores were significantly associated with an increased risk of exacerbations after adjustment for potential confounders such as age, gender, body mass index, smoking status and clinical history. Specifically, patients in the highest CAT score category had a 1.50-fold increased risk of any exacerbation and a 2.01-fold increased risk of a moderate-to-severe exacerbation compared with those in the lowest category.

The researchers also found that that the uncategorised CAT score provided predications of a similar magnitude and that predictions did not change significantly when tested in subgroups of patients with cardiovascular comorbidity.

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