Relationship between preoperative modified frailty index, immune-inflammation index, and outcomes of colorectal cancer surgery in older patients

BACKGROUND With the aging of the population, the proportion of older patients with colorectal cancer (CRC) is increasing annually. Preoperative frailty and chronic inflammatory responses may increase the risk of postoperative complications and affect long-term survival. AIM To assess modified frailty index (mFI) and systemic immune-inflammation index (SII) for predicting postoperative prognosis in older patients with CRC. METHODS We retrospectively analyzed 247 older patients with CRC who underwent radical resection. The SII was calculated as platelet count × neutrophil count/lymphocyte count. Patients were grouped by complication occurrence. Univariate and multivariate analyses were performed for mFI, SII, and postoperative complications. Using receiver operating characteristic curve analysis, the critical SII value for predicting postoperative recurrence was identified, which was then used to divide patients into high/low mFI and high/low SII groups. Using Kaplan-Meier method between-group survival curves were drawn. RESULTS The 30-day complication rate was 12.55%. Multivariate logistic regression analysis identified smoking history [odds ratio (OR) = 4.822], prolonged operation time (OR = 1.037), and elevated preoperative mFI (OR = 9.342) and SII (OR = 1.002) as independent risk factors for postoperative complications (P < 0.05). On survival analysis, the average recurrence-free survival (RFS) for patients with a low mFI was 47.04 months [95% confidence interval (CI): 45.30-48.79], significantly better than the 33.83 months (95%CI: 31.31-36.36) for patients with a high mFI (log-rank, P < 0.001). The average RFS for patients with a low SII was 47.00 months (95%CI: 45.07-48.94), significantly better than the 40.06 months (95%CI: 31.37-43.74) for those with a high SII (log-rank, P < 0.001). CONCLUSION In older patients with CRC, the preoperative mFI and SII were significantly correlated with postoperative complications and RFS, warranting closer attention to early recurrence detection and intervention.