Significant parameters in CBC profiles for expecting outcomes of COPD

Background: Since complete blood count (CBC) can be easily and repeatedly measured at the usual clinical setting, the various CBC biomarkers including eosinophil count, neutrophil-lymphocyte ratio, platelet-lymphocyte ratio, and eosinophil-basophil ratio have been studied for COPD. Recently, the roles of eosinophil-platelet interactions were emphasized from in vitro or animal model studies. Here, we extensively evaluated the impacts of CBC profiles including eosinophil-platelet interaction on clinical outcomes of stable COPD in Korean cohorts. Methods: The COPD patients enrolled in Korean COPD Subtype Study (KOCOSS) or Seoul National University Airway Registry between 2011 and 2018 were analyzed. Based on the CBC profiles at the time of enrollment, their association with the rate of acute exacerbation (AE) within one year and the annual decline rate of forced expiratory volume in 1 second (FEV1) were evaluated by using negative binomial regression model and linear mixed-effects model. Results: Among 2,221 COPD patients, 1,202 patients were analyzed. Multivariate analysis showed that baseline FEV1 is the most significant factor for both AE rate and FEV1 decline rate. High EBR is associated with high moderate-to-severe AE rates, and both EBR and NLR were related to severe AE rates in addition to FEV1 and the history of AE events. The patients with low eosinophil counts tended faster FEV1 decline, however, platelet counts or eosinophil-platelet interaction terms were not significant factors for outcomes. Conclusion: EBR and NLR are independent prognostic markers for the moderate-to-severe AE and FEV1 decline rate of stable COPD, while eosinophil-platelet interaction had a limited role in predicting clinical outcomes.