Fig. 1

AE-COPD confirmed by increases in BCSS total score and serum CRP levels. AE-COPD events were identified by physician diagnosis (after exclusion of pneumonia by chest radiograph) plus the clinical decision to prescribe oral steroids or antibiotics. Although these decisions were blinded to biomarker results, the diagnosis of AE-COPD was retrospectively confirmed by highly significant increases in (a) BCSS total scores and (b) serum CRP levels. Open circles represent individual subjects; mean ± SEM of the grouped data are shown by the single red circles. The Wilcoxon matched-pairs signed rank test was used to determine significant differences between visits