Blood Eosinophils in Chinese COPD Participants and Response to Treatment with Combination Low-Dose Theophylline and Prednisone: A Post-Hoc Analysis of the TASCS Trial

Background and Objectives: The burden of chronic obstructive pulmonary disease (COPD) disproportionately affects patients in low to middle-income countries. Although the Theophylline and Steroids in COPD Study (TASCS) showed no clinical benefit from administering low-dose theophylline and prednisone in COPD patients compared to placebo, it was hypothesized that those with elevated blood eosinophil counts would receive clinical benefit from the intervention. Methods: This was a post-hoc analysis of the TASCS dataset – a double-blinded, placebo-controlled trial conducted in patients with moderate–severe COPD in China. Participants were allocated 1:1:1 to low-dose oral theophylline (100mg bd) and prednisone (5mg qd; PrT), theophylline (100mg bd) and prednisone-matched placebo (TP), or double-matched placebo (DP) groups and followed-up for 48 weeks. A baseline count of ≥ 300 eosinophils/μL blood was categorized as elevated/eosinophilic, and the primary outcome was the annualized moderate-severe exacerbation rate. Results: Of 1487 participants eligible for analysis, 325 (22%) were eosinophilic. These participants were predominantly male (82%), had a mean (SD) age of 64 (± 8) years and a predicted forced expiratory volume in 1s (FEV 1 ) of 43% (± 16). The annualized moderate–severe exacerbation rate was significantly higher in the PrT group compared to the pooled results of the TP and DP groups (incidence rate ratio = 1.6; ([95% CI 1.06– 1.76]) p = 0.016). Changes in spirometry values and reported disease impact scores (St. George’s Respiratory Questionnaire and COPD Assessment Test) at week 48 were not significantly different between groups. Conclusion: Combination low-dose theophylline and prednisone was associated with a significant increase in the annual moderate-severe exacerbation rate in participants with a blood eosinophil count ≥ 300 cells/μL compared to placebo. Keywords: eosinophil, COPD, clinical trial, China, theophylline, prednisone