Relationship Between Blood Eosinophils and Systemic Corticosteroid Therapy in COPD Exacerbation

To assess the relationship between the duration of systemic corticosteroid therapy and blood eosinophil counts in patients with acute exacerbations of chronic obstructive pulmonary disease (COPD).

This study included 292 patients with acute COPD exacerbations treated with daily intravenous injections of 40 mg/day methylprednisolone at the Department of Respiratory Medicine, Anhui No.2 Provincial People's Hospital, Hefei, China. The study subjects were divided into two groups - (1) a low-dose group (n = 136) that included patients treated with methylprednisolone for less than or equal to 5 days and (2) a high-dose group (n = 156) that included patients treated with methylprednisolone for more than 5 days. The blood eosinophil counts were analyzed for both the patient groups, and an optimal cut-off value was calculated to distinguish between the two groups. The study endpoints were readmission or deaths within 30 days or 180 days and re-infections within 90 days after hospital discharge.

The mean blood eosinophil counts in the low- and high-dose groups were 0.15 × 10⁹/L (0.11-0.23 × 10⁹/L) and 0.08 × 10⁹/L (0.04-0.12 × 10⁹/L), respectively (P < 0.01). Receiver operating characteristic (ROC) curve analysis showed that the cut-off value for the blood eosinophils to distinguish the two patient groups was 0.115 × 10⁹/L with a sensitivity and specificity of 72.8% and 72.4%, respectively. The number of readmissions between the two groups at 30 days and 180 days after hospital discharge did not show any significant differences (P = 0.292, P = 0.398). The follow-up data showed significantly higher rate of re-infections in the high-dose group (24/136) within 90 days after hospital discharge compared to the low-dose group (9/156) (P = 0.018).

In patients with acute exacerbations of COPD, blood eosinophil counts of ≥0.115 × 10⁹/L were associated with effective response to corticosteroid therapy in ≤5 days.