Background/Objectives: Nutrition in inflammatory bowel disease (IBD) is a central concern for both patients and healthcare professionals, as it plays a key role not only in daily life but also in disease outcomes. The Mediterranean diet represents a healthy dietary pattern that may be suitable in many cases of IBD. Among other factors, health literacy (HL) influences patients’ dietary habits and their ability to follow nutritional recommendations. The aim of this study was to assess HL and dietary patterns in adolescent and pediatric patients with IBD. Methods: We conducted a cross-sectional study that included a total of 99 participants (36 patients with IBD receiving biological therapy recruited from a single center and 63 healthy controls). HL was assessed using the Newest Vital Sign (NVS) tool regardless of disease activity, whereas diet quality was evaluated by the KIDMED questionnaire exclusively in patients in remission. Linear regression models were used to evaluate the effects of sex, age and group (patients vs. control) on NVS and KIDMED scores. Results: Most participants (87.9%) had an adequate HL, which was positively associated with age. While the most harmful dietary habits (such as frequent fast-food consumption) were largely absent in the patient group, KIDMED scores indicated an overall poor diet quality. Conclusions: Although HL increased with age and was generally adequate in this cohort, it did not translate into healthier dietary patterns as measured by the KIDMED score. Further research with larger, more diverse samples is needed to clarify the relationship between HL and dietary adherence in adolescents with IBD.

Background: Biological therapy is frequently used for the treatment of inflammatory bowel disease (IBD); however, the long-term efficacy of anti-tumor necrosis factor-alpha (TNF−α) therapies, such as infliximab (IFX) and adalimumab (ADA), is often compromised by the development of antidrug antibodies (AIFX and AADA, respectively). While several individual factors are known to contribute to immunogenicity, the complex, interactive effects of various clinical variables have not been fully elucidated in a real-world setting. Methods: We conducted a hierarchical logistic regression analysis on a retrospective cohort of 153 pediatric and adult IBD patients receiving IFX or ADA therapy to identify clinical factors and their interactions associated with AIFX/AADA positivity. The analysis progressively incorporated demographic, disease-related, and treatment-related variables, culminating in a model that included two- and three-way interaction terms. Results: Our final model demonstrated modest predictive power, with a Nagelkerke R² of 0.287, explaining less than 30% of the variance in antibody positivity using readily available clinical data (AUC of 0.806, 71.0% sensitivity and 77.6% specificity). Key predictors included the type of biological therapy (IFX vs. ADA) and the duration of treatment, with IFX therapy being a significant independent predictor (OR = 6.940, p = 0.004) for antibody positivity. Importantly, we identified novel three-way interactions, revealing that the combined effect of age at disease onset, IBD subtype, and biological therapy type significantly influences antibody formation (p = 0.042), particularly in childhood-onset ulcerative colitis patients treated with IFX. A similar interaction was found for treatment duration, IBD subtype, and therapy type (p = 0.042), where the risk of antibody positivity with IFX increased significantly with treatment length, particularly in UC patients. Conclusions: This study highlights that the combination of routine clinical variables in IBD offers a data-driven, mechanistically insightful framework, supporting the prediction of AIFX/AADA positivity to a modest extent. This framework requires prospective and external validation before clinical implementation.

Background: Ustekinumab (UST) and vedolizumab (VDZ) are established therapies for Crohn’s disease (CD) and ulcerative colitis (UC), including in patients with prior tumour necrosis factor-alpha inhibitor (anti-TNF) failure. Trough levels (TRLs) and antidrug antibodies (ADAs) are among several factors associated with therapeutic response. The aim of this study was to retrospectively identify factors associated with suboptimal TRL and ADA presence in a large, multicentre, cross-sectional cohort. Methods: TRLs and ADAs for VDZ and UST were measured routinely during therapy. A Cox proportional hazards model was used to identify clinical and treatment-related factors associated with suboptimal TRLs. Results: A total of 184 patients (78 children and 106 adults) with inflammatory bowel disease (IBD) were included; 104 and 80 were treated with UST and VDZ, respectively. TRLs were measured as part of routine clinical care between 2022 and 2025. Of the 184 patients, 80 (43.48%) had previously received both infliximab and adalimumab. Overall, 103 patients (55.98%) had received at least two advanced therapies (infliximab, adalimumab, VDZ, UST or a small-molecule inhibitor (SMI)) before the current biologic therapy. In exploratory Cox analyses, prior UST exposure (HR = 4.13, 95% CI = 1.58–10.81, p = 0.004) and UC subtype (HR = 2.83, 95% CI = 1.39–5.76, p = 0.004) were associated with a higher hazard of suboptimal TRL, whereas longer duration of prior biologic therapy (HR = 0.89, 95% CI = 0.82–0.96, p = 0.003) and current VDZ treatment (HR = 0.36, 95% CI = 0.16–0.82, p = 0.014) were associated with a lower hazard. In a cross-sectional logistic model accounting for time on therapy, only longer duration of prior biologic therapy remained significantly associated with suboptimal TRL. Prior UST exposure was associated with ADA presence in the cross-sectional model, although the estimate was imprecise and sensitive to model specification. Conclusions: Prior UST exposure, UC subtype and current VDZ therapy were associated with suboptimal TRLs in exploratory Cox analyses; however, these associations were not reproduced in the cross-sectional logistic model and were sensitive to adjustment for inflammatory burden. Longer duration of prior biologic therapy remained associated with lower odds of suboptimal TRL in the cross-sectional analysis. The observed association between prior UST exposure and ADA presence was imprecise and model-dependent. Given the study’s retrospective design and limited sample size, these findings should be considered preliminary and require validation in larger prospective cohorts.