ERAS Implementation Fidelity, Care Complexity, and Postoperative Outcomes in Oncological Colorectal Surgery: A Real-World Observational Study

Background: Enhanced Recovery After Surgery (ERAS) programmes are structured perioperative care pathways in which clinical outcomes are closely linked to the degree of implementation fidelity. However, the interaction between ERAS adherence, care complexity, and postoperative outcomes in real-world settings remains insufficiently explored. Objective: To evaluate the association between ERAS adherence and postoperative length of stay in oncological colorectal surgery and to analyse whether Care Complexity Individual Factors (CCIFs) influence this relationship. Methods: A retrospective observational cohort study was conducted in two university hospitals in Barcelona, including 90 adult patients undergoing elective colorectal cancer surgery (2022). ERAS adherence was assessed globally and by phase (pre-, intra-, and postoperative) using structured indicators. CCIFs were classified into five domains. Associations between adherence, care complexity, and outcomes were analysed using bivariate methods. Results: Overall adherence was 64%. Higher adherence was associated with shorter hospital length of stay (median 4 vs. 5 days; p = 0.033) and greater compliance with expected length of stay (37.8% vs. 17.0%; p = 0.047). Adherence varied across perioperative phases, with higher compliance in the preoperative phase and lower compliance postoperatively. Care complexity was high (mean CCIF 2.62) and was not significantly associated with adherence or compliance with expected length of stay. Conclusions: Higher ERAS adherence is associated with shorter hospital stay in oncological colorectal surgery within a real-world context. These findings support the importance of implementation fidelity across the perioperative pathway. Further research incorporating multivariable analyses and patient-centred outcomes is needed to better understand the interaction between care complexity and recovery trajectories.