Beyond Inflammation: Sarcopenia and Disease Phenotype Predict Unfavourable Course in Crohn’s Disease—A Retrospective Observational Study

Introduction: Chronic inflammation in Crohn’s disease (CD) is associated with systemic alterations, including the loss of skeletal muscle mass. While nutritional deficits are known to impact clinical trajectories, the specific prognostic value of muscle wasting remains underutilised. The primary objective of this study is to construct a composite score integrating sarcopenia with paraclinical parameters to predict an unfavourable disease outcome (UO) more accurately. Materials and Methods: We conducted a retrospective study of patients with CD who were hospitalized at our institution between January 2020 and June 2024 and were treated with biologics or small molecules. Using previous CT scans, we measured skeletal muscle area (SMA) and skeletal muscle index (SMI) to assess their association with disease outcomes. Univariate and multivariate analyses were performed to identify significant predictors of UO, and Area Under the Curve (AUC) values were calculated to assess the predictive performance and to construct a composite prognostic score. Results: Multivariate analysis in the study group (52 patients) identified sarcopenia (low SMI), faecal calprotectin levels >129 μg/g, and complicated disease behaviour (Montreal B2/B3) as independent predictors of UO. Integrating these parameters into a composite risk score resulted in a promising predictive model with an Area Under the Curve (AUROC) of 0.864, significantly outperforming individual biomarkers. Conclusions: We performed a hypothesis-generating study suggesting that nutritional assessment in CD could provide an important benefit in stratifying patients for whom additional nutritional interventions may enhance the long-term outcomes.