The COPD Assessment Test (CAT) is useful for determining severity of chronic obstructive pulmonary disease (COPD) exacerbations and for measuring recovery after exacerbations and pulmonary rehab, according to two new studies.
In the first study, U.K. researchers assessed whether the CAT, an eight-item questionnaire about COPD symptoms and health status, could reliably score the severity of COPD exacerbations. The study involved 161 patients who completed the CAT between April 2010 and June 2011 while stable, during an exacerbation and during recovery. Patients were also required to complete daily diary cards noting their daily peak expiratory flow rate, the hours they spent outside the home, and increases in respiratory symptoms. To be included in the study, patients had to have a post-bronchodilator FEV1 of 80% of predicted or less and an FEV1/FVC ratio less than 0.7. Patients who had a history of other significant respiratory disease and those who could not complete daily records of their symptoms were excluded. The study was published early online Jan. 26 by the American Journal of Respiratory and Critical Care Medicine.
During the period assessed, patients had a total of 152 exacerbations, in which CAT scores increased from an average of 19.4±6.8 at baseline to 24.1±7.3 during the exacerbation (P<0.001). Patients who had frequent exacerbations had significantly higher CAT scores at baseline than those who did not (19.5±6.6 vs. 16.8±8.0; P=0.025). Increases in CAT score at exacerbation were significantly associated with FEV1 decreases (P=0.032), and median exacerbation recovery time was significantly related to the time elapsed until the CAT score returned to baseline (P=0.012).
The authors concluded that the CAT provided a reliable way to score COPD exacerbation severity and that patients who have frequent exacerbations are likely to have higher CAT scores at baseline. Because the CAT can be completed easily and quickly, they said, it could be used as part of COPD care bundles. This would potentially help patients get quick treatment for exacerbations, improving recovery and decreasing hospitalizations. They called for additional evaluation of the CAT to determine how it can best be integrated into clinical practice.
The second study looked at whether the CAT could determine changes in patients' health during recovery from a COPD exacerbation and after pulmonary rehabilitation. Two cohorts were separately examined, the first involving 67 patients who had received a clinician's diagnosis of an exacerbation between February and April 2009 and the second involving 64 patients with stable COPD beginning pulmonary rehabilitation from July to December 2009. Researchers assessed how well the CAT detected changes in health status during days 1 to 14 of an exacerbation (cohort 1) and during days 1 to 42 of pulmonary rehabilitation (cohort 2) by examining correlations between the CAT and various outcome measures. The study was published early online Jan. 26 by Chest.
The mean improvement in CAT score over 14 days in cohort 1 was −1.4±5.3 (P=0.03). Patients and clinicians defined patients as responding or not responding to treatment, and under both definitions, those in the responding group had a larger change in CAT score (patients' definitions, −2.8±4.6 vs. −0.0±5.6 [P=0.03]; clinicians' definitions, −2.6±4.4 vs. −0.2±5.9 [P=0.08]). In cohort 2, the mean improvement in CAT score for patients undergoing pulmonary rehabilitation was -2.2±5.3 (P=0.002). In comparisons with other measures of COPD health status, a strong correlation was seen between change in CAT score and change in score on the Chronic Respiratory Questionnaire-Self-Administered Standardized form (CRQ-SAS). Correlations were less strong, however, between change in CAT score and the St. George's Respiratory Questionnaire (SGRQ) in cohort 1 and between change in CAT score and 6-minute walk distance in cohort 2.
The authors concluded that the CAT can be used to detect changes in health status after a COPD exacerbation and after pulmonary rehabilitation and is comparable to other, more complicated measures. They noted that the CAT was able to distinguish between patients who did and did not respond to therapy after an exacerbation, indicating that those whose CAT score does not change or worsens at 14 days may need different or additional treatment. In addition, they wrote, the CAT's performance in cohort 2 indicates that it could be used routinely to assess progress after pulmonary rehabilitation instead of other measures that are more time-consuming and more complex.