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DOP031 Subtherapeutic serum infliximab trough levels and complete mucosal healing are associated with sustained clinical remission after infliximab discontinuation in paediatric Crohn's disease patients

Kang B.*1, Lee K.1, Kim K.2, Lee J.H.3, Choe Y.H.1

1Samsung Medical Center, Sungkyunkwan University School of Medicine, Department of Pediatrics, Seoul, South Korea 2Samsung Medical Center, Biostatistics and Clinical Epidemiology Center, Seoul, South Korea 3Chungbuk National University Hospital, Chungbuk National University College of Medicine, Department of Pediatrics, Cheongju, South Korea

Background

There is limited data regarding the clinical course of Crohn's disease (CD) after stopping infliximab (IFX) treatment in the paediatric population. We aimed to investigate the outcome of paediatric CD patients who had discontinued IFX under clinical remission by combined immunosuppression with IFX and thiopurines, and to reveal risk factors associated with clinical relapse in these patients.

Methods

We conducted a retrospective observational study from January 2009 to June 2016 at the Department of Pediatrics, Samsung Medical Center. The subjects were 63 patients who had discontinued scheduled IFX under sustained corticosteroid-free clinical remission for at least 1 year by combined immunosuppression with IFX and azathioprine, and had been followed for at least 1 year after IFX cessation. Relapse free survival rate and the median time to relapse was estimated by Kaplan-Meier survival analysis. Demographic, clinical, biochemical, and endoscopic factors at IFX cessation were evaluated for their association with clinical relapse using Cox proportional hazard regression analysis.

Results

After a median follow-up period of 4.3 years (range: 1–7.5 years), 60% (38/63) patients had experienced a clinical relapse. The estimated cumulative relapse rate for 1-, 2-, 4-years were 19%, 36%, and 62%, and the median relapse time was 3.3 years from IFX cessation. According to multivariable Cox proportional hazard regression analysis, serum IFX trough levels of ≥2.5 μg/mL and incomplete mucosal healing status were associated with clinical relapse [hazard ratio (HR)=7.199, 95% confidence interval (CI)=1.641–31.571, p=0.009, and HR=3.628, 95% CI: 1.608–8.185, p=0.002, respectively]. Retreatment with IFX was effective in 30/33 patients (91%).

Figure 1. Clinical relapse in patients stratified by mucosal healing status at infliximab cessation.

Figure 2. Clinical relapse in patients stratified by infliximab trough levels and mucosal healing status at infliximab cessation.

Figure 3. Clinical relapse in patients stratified by infliximab trough levels at infliximab cessation.

Conclusion

Approximately 50% of patients with paediatric luminal CD under sustained clinical remission for at least 1 year by combined immunosuppression will experience a relapse within 3.3 years after IFX cessation. A subgroup of patients with subtherapeutic serum IFX trough levels and a complete mucosal healing status at IFX cessation may better sustain clinical remission under thiopurines after IFX discontinuation.