Physiological impairments and exacerbation risk in COPD patients with less symptom and no frequent exacerbation history

Introduction: Current Global initiative for COPD(GOLD) advocates ABCD classification for treatment strategy. Although FEV1 was removed in 2017 GOLD report, it9s not fully understood whether the removal of physiological evaluation would affect the predictivity of future exacerbations. This study focused on COPD patients without frequent exacerbation history(group A and B) to test the hypothesis that impaired FEV1 or respiratory oscillometry index would be associated with a higher risk of exacerbation independent of ABCD classification. Methods: This retrospective analysis of a prospective cohort study included stable patients with COPD who underwent spirometry, respiratory oscillometry and chest CT, completed mMRC dyspnea scale and COPD assessment test and were followed up for 5 years to monitor exacerbations. Results: Of total 134 male patients enrolled, 119(88.8%) were classified into group A and B. In univariable Cox proportional hazard model, hazard ratios of FEV1 and resonant frequency(Fres) for exacerbation risk in group A and B patients were the highest among physiological indices. In multivariable Cox proportional hazard model, lower FEV1 and higher Fres were associated with shorter time to first exacerbation in patients with group A and B independent of ABCD classification(A vs B), age, BMI, smoking status, emphysema and airway disease. Conclusions: Adding FEV1 or Fres to ABCD tool could help identifying patients with higher risk of exacerbation. Physiological evaluation including spirometry or respiratory oscillometry and ABCD classification tool should be used together to estimate exacerbations risk for preventive intervention in patients with COPD.