Association between pre-reversal systemic inflammation response index and low anterior resection syndrome in rectal cancer patients: a retrospective cohort study

Purpose: This study aims to explore the relationship between the systemic inflammation response index (SIRI) and the development of low anterior resection syndrome (LARS) in rectal cancer patients after ileostomy closure. Methods: This retrospective cohort study included 116 rectal cancer patients who underwent low anterior resection with diverting ileostomy and subsequent ileostomy reversal at the Fourth Hospital of Hebei Medical University between August 2022 and April 2024. SIRI was calculated from complete blood counts obtained within 1 week prior to ileostomy reversal. Postoperative bowel function was evaluated using the validated LARS questionnaire at 12 months after ileostomy closure. The association between SIRI and major LARS was examined using multivariable logistic regression models. A spline-based smooth curve fitting approach was applied to assess potential nonlinearity, and subgroup analyses were performed to explore effect modification across clinically relevant strata. Results: Among the 116 patients, 47 (40.5%) developed major LARS, while 69 (59.5%) had no or minor LARS. Compared to the no/minor LARS group, the major LARS group showed significantly higher SIRI levels (P = 0.011). Multivariate logistic regression analysis indicated that elevated SIRI was associated with a 295% increased risk of major LARS (OR: 3.95; 95% CI: 1.24, 12.61; P = 0.020). Subgroup analysis revealed that this association was more pronounced in patients with a lower anastomotic height (≤4 cm), younger age (≤60 years), shorter interval to stoma closure (Tertile 1), and those who did not receive adjuvant therapy. Conclusion: SIRI may become a biomarker for identifying patients at higher risk of developing severe LARS after rectal cancer surgery. Integrating SIRI into preoperative assessments could allow for early intervention and personalized management strategies to mitigate the severity of LARS.