High systemic inflammation response index level is associated with an increased risk of lower extremity deep venous thrombosis: a large retrospective study

The association between inflammation and venous thromboembolism (VTE) has attracted increasing research interest. Recently, the systemic inflammation response index (SIRI) has been proposed as a novel inflammatory biomarker, but its potential association with lower extremity deep venous thrombosis (LEDVT) has not been investigated. Thus, this study aimed to explore the association between SIRI and LEDVT risk in a large sample over a 10-year period (2012-2022).All hospitalized patients who underwent lower extremity compression ultrasonography (CUS) examinations were consecutively identified from our hospital information system database. Multivariate logistic regression analysis was used to investigate the association between SIRI and LEDVT risk. Sensitivity, restricted cubic spline and subgroup analyses were also performed.In total, 12643 patients were included, and 1346 (10.6%) LEDVT events occurred. After full adjustment, a higher SIRI level was significantly associated with an increased risk of LEDVT (odds ratio [OR] = 1.098, 95% confidence interval [CI]: 1.068-1.128, p < 0.001), and patients in quartile 4 had a 2.563-fold higher risk of LEDVT than those in quartile 1 (95% CI: 2.064-3.182, p < 0.001). A nonlinear relationship was observed (P for nonlinearity < 0.001), with an inflection point of 4.17. Below this point, each unit increase in SIRI corresponded to a 35.3% increase in LEDVT risk (95% CI: 1.255-1.458, p < 0.001). No significant difference was found above the inflection point (OR = 1.015, 95% CI: 0.963-1.069, p = 0.582). Sensitivity and subgroup analyses confirmed the robustness of the association. This association also existed in both distal and proximal LEDVT.A High SIRI is significantly associated with an increased risk of LEDVT in hospitalized patients. Given that the SIRI is a readily available biomarker in clinical settings, its potential clinical use deserves further exploration.A High SIRI is significantly associated with an increased risk of LEDVT in hospitalized patients.The association between SIRI and LEDVT risk was nonlinear, with an inflection point of 4.17.A positive association was observed below the inflection point, but no significant difference was found above this point.