In subgroup analysis, all statistically significant subgroups showed that SII was a risk factor for postoperative sepsis, such as age ≥65 years old (OR = 5.52, 95% CI: [1.73–17.57], p < .001), ASA III–IV (OR = 3.83, 95% CI: [1.47–9.97], p < .001), blood loss <100 mL (OR = 4.26, 95% CIL [1.60–11.33], p < .001), ALB <35 g/L (OR = 4.71, 95% CI: [1.54–14.42], p < .001), HGB <115 g/L (OR = 3.51, 95% CI: [1.22–10.09], p = .001), Cr <116 μmol/L (OR = 2.36, 95% CI: [1.04–5.37], p = .006). The gene discussed is ALB; the disease is Sepsis.