Comparison of Peak Expiratory Flow(PEF) and COPD Assessment Test (CAT) to Assess COPD Exacerbation Requiring Hospitalization: A Prospective Observational Study

Background: Acute exacerbation of chronic obstructive pulmonary disease (COPD) resulting in hospitalization is significantly associated with the increased morbidity and mortality, but there is a lack of an effective method to assess it. This study aimed to compare the ability of peak expiratory flow (PEF) and COPD assessment test (CAT) to assess COPD exacerbations requiring hospitalization.

Methods: A cohort of 110 patients with moderate to severe COPD was studied over a period of 12 months, and their daily morning PEFs and CAT scores were recorded throughout the study.

Results: After 12 months of follow-up, 72 patients experienced 156 COPD exacerbations, 74 (47%) that resulted in hospitalization and 82 (53%) that did not result in hospitalization. Change in CAT score from baseline to exacerbation was significantly related to change in PEF and Spearman's rho =0.375 (95% CI, 0.227 to 0.506; p < .001). Change in PEF and CAT score from baseline to hospitalized exacerbation was significantly larger than that from baseline to non-hospitalized exacerbation (p < .05). Multivariable analysis indicated that ΔPEF (OR 1.11, 95% CI 1.06-1.16, p < .001) and ΔCAT (OR 1.64 95% CI 1.18-2.27, p = .003) were independently associated with risk of hospitalized exacerbation. ROC analysis indicated that the optimal cutoff value of ΔPEF for identifying hospitalized exacerbation was 49 L/min (27% from baseline), with a sensitivity and specificity of 82.7% and 76.7% (area under the curve [AUC] = 0.872 (95% CI 0.80-0.944, p < .05). The optimal cutoff value of ΔCAT score for identifying hospitalized exacerbation was 10.5 (63% from baseline), with a sensitivity and specificity of 67.3% and 77.4% [AUC]=0.763 (95% CI 0.67-0.857, p < .05). The AUC of ΔPEF and ΔCAT combined for the identification of hospitalized exacerbation was 0.900 (95% CI 0.841-0.959, p < .05), which was larger than that of ΔCAT or ΔPEF.

Conclusions: ΔPEF and ΔCAT were independently associated with risk of hospitalized exacerbation. Compared with CAT, PEF was superior to identify hospitalized exacerbation. Identification via PEF and CAT combined is more effective than using PEF or CAT alone. These results help to assess the severity of COPD exacerbation and provide valuable information for clinical decision-making.