Optimal dose of maintenance steroid therapy for relapse of chronic eosinophilic pneumonia: a multicentre retrospective study.

Background: Long-term maintenance steroid therapy (MST) is often necessary for repeated relapses of chronic eosinophilic pneumonia (CEP). Because relapse does not indicate a worse prognosis, determining the optimal steroid dose to avoid overtreatment presents a clinical challenge. Our primary objective was to evaluate the optimal MST dose to prevent repeated relapses, and the secondary objectives included identifying serum eosinophil count at relapse and background factors of relapse.

Methods: A multicentre retrospective study was conducted on patients with steroid-treated CEP. Background characteristics were compared between the non-relapse and relapse groups. The optimal MST dose was determined based on dose at relapse and the final relapse prevention dose. Additionally, serum eosinophil count at relapse was assessed.

Results: A total of 79 patients were included, with 44 in the non-relapse group and 35 in the relapse group. The prednisolone doses required to achieve relapse-free rates of 50% (ED₅₀) were 7.2 mg (95% CI, 4.6 to 23.6). The median serum eosinophil count at relapse was 1125 /µL (IQR, 735-2108). No clinically significant background factors were identified between the non-relapse and relapse groups.

Conclusion: Our study demonstrated that a prednisolone dose of 7.2 mg achieved a 50% relapse-free rate in the relapse group. Based on these findings, we encourage clinicians to evaluate individual minimum effective steroid doses.