The ImproveCareNow Registry: Prediction of different remission rates in pediatric ulcerative colitis.

OBJECTIVES: Identifying predictors of clinical remission in pediatric ulcerative colitis (UC) will impact the therapeutic approach. We aimed to predict time to first (TFR), corticosteroid-free (TCSFR, ≥3 months corticosteroid withdrawal), and sustained remission (TSR, ≥6 months). METHODS: This retrospective study analyzed de-identified prospectively collected data from 2383 patients enrolled in ImproveCareNow (2007-2023). We included UC patients under 18 years at diagnosis. Remission was defined as a Pediatric UC Activity Index (PUCAI; <10 points). The Statistical Package for the Social Sciences version 29 with multiple imputation for missing data was used for statistical analysis. Cox regression identified predictors at diagnosis/enrollment (T0) or first visit (T1) on the outcomes (n = 1785). This study received ethics committee approval (23135-ICN_UC). RESULTS: Mean TFR was 177.7 days, predicted by disease extent (p > 0.05) at T0 and history of severe UC (hazard ratio [HR] = 1.142, p = 0.05) before inclusion. In patients not reaching remission at T1 (subgroup; n = 964), TFR was predicted by PUCAI (confounder; moderate HR = 0.867 or severe disease HR = 0.697, p < 0.1) at T1 and history of severe UC (HR = 1.292, p = 0.007) before T1 (mean 25 days SEM 0.7). Mean TCSFR was 569.6 days, predicted by PUCAI (only mild HR = 0.728 and moderate HR = 0.559, p < 0.001) and use of corticosteroids (HR = 0.668, p < 0.001) at T1 (mean 32 days SEM 0.9). Mean TSR was 631.0 days, predicted by PUCAI (only mild HR = 0.721 and moderate HR = 0.541, p < 0.001) and the use of oral aminosalicylates (HR = 0.793, p = 0.003) at T1 (mean 30 days SEM 0.7). CONCLUSIONS: Several clinical parameters in early disease course predict remission with increasing PUCAI as useful negative predictor.