Clinical factors associated with early high-output stoma and 30-day readmission: a retrospective cohort study.

High-output stoma (HOS) is a clinically relevant complication after stoma formation and may increase postoperative morbidity and healthcare utilization. This study aimed to evaluate clinical, biochemical, and perioperative factors associated with early HOS and to examine its relationship with postoperative outcomes and 30-day readmission. This retrospective single-center cohort study included 159 adult patients who underwent ileostomy or colostomy formation between January 2015 and January 2025. Data were extracted from electronic medical records, operative reports, and postoperative nursing documentation. Early HOS was defined as stoma output exceeding 1500 mL/day during the early inpatient postoperative period. Univariable and multivariable logistic regression analyses were performed to evaluate factors associated with HOS. Hierarchical modeling assessed the incremental contribution of predefined variable domains, and exploratory mediation analysis examined the relationship between HOS, dehydration, and readmission. Early HOS developed in 46 patients (28.9%). In multivariable analysis, ileostomy formation (OR = 4.12, p = 0.002), longer operative time (OR = 1.01 per minute, p = 0.01), lower albumin level (OR = 0.55, p = 0.02), lower sodium level (OR = 0.90, p = 0.02), and diuretic use (OR = 2.58, p = 0.03) were independently associated with early HOS. Model discrimination increased across hierarchical blocks, with AUC values ranging from 0.66 to 0.86. Patients with HOS had higher rates of dehydration, acute kidney injury, prolonged hospital stay, and 30-day readmission. HOS remained independently associated with readmission (OR = 2.87, p = 0.009), and exploratory mediation analysis suggested partial mediation through dehydration. Early HOS was common after stoma formation and was associated with baseline biochemical vulnerability, perioperative factors, and adverse postoperative outcomes. Given the retrospective design and heterogeneity between ileostomy and colostomy, these findings should be interpreted as exploratory and require confirmation in prospective, multicenter, stoma type-specific studies.