Postoperative cerebral infarction after major thoracic and abdominopelvic surgery: a retrospective single-centre cohort study of incidence, risk factors, and outcomes.

BACKGROUND: Postoperative cerebral infarction (POCI) is an uncommon but potentially fatal complication of major non-cardiac surgery and is associated with higher in-hospital mortality, intensive care unit (ICU) admission, and subsequent mortality. The contribution of preoperative composite inflammatory and coagulation indices, including the systemic immune-inflammation index (SII), to POCI risk stratification has not been well characterized in Korean thoracic and abdominopelvic surgical cohorts. METHODS: We conducted a retrospective cohort study using the INformative Surgical Patient dataset for Innovative Research Environment (INSPIRE). Of 15,225 eligible patients who underwent elective or emergency thoracic or abdominopelvic surgery, 15,138 met inclusion criteria. The primary outcome was confirmed POCI. Independent associations with POCI were assessed by multivariable logistic regression (adjusted odds ratios (aORs) with 95% confidence intervals). Three machine learning classifiers were trained and evaluated by five-fold stratified cross-validation. Survival was compared using a pre-specified fixed-endpoint analysis (1-year all-cause mortality). Kaplan-Meier estimation was provided as supporting description. RESULTS: POCI was confirmed in 277 of 15,138 patients (1.83%; 95% CI: 1.63-2.06%). In multivariable logistic regression, the factors independently associated with POCI were advanced age (aOR: 1.65 per 10-year increment; 95% CI: 1.46-1.88), hypertension (aOR: 5.92; 95% CI: 4.56-7.68), atrial fibrillation (aOR: 4.21; 95% CI: 2.60-6.79), chronic kidney disease (aOR: 2.47; 95% CI: 1.56-3.90), and peripheral arterial disease (aOR: 2.45; 95% CI: 1.27-4.72) (all p < 0.01). In unadjusted descriptive comparisons, POCI patients had higher preoperative neutrophil-to-lymphocyte ratio (NLR; median 3.1 vs. 2.5; p < 0.001), systemic immune-inflammation index (SII; 694.4 vs. 577.5; p = 0.006), and fibrinogen-to-albumin ratio (FAR; 85.5 vs. 76.3; p < 0.001). However, none of these indices was independently associated with POCI after adjustment (e.g. NLR aOR: 1.21; 95% CI: 0.93-1.58; p = 0.155). No consistent pattern of greater intra-operative hypotension was observed. In-hospital mortality (5.4% vs. 1.6%; OR: 3.56; 95% CI: 2.10-6.03) and ICU admission (42.6% vs. 22.8%; OR: 2.52; 95% CI: 1.98-3.20) were higher in the POCI group (both p < 0.001). One-year all-cause mortality was 14.8% in the POCI group versus 5.8% in controls (OR: 2.83; 95% CI: 2.02-3.96; p < 0.001), and the Kaplan-Meier log-rank comparison was non-significant (p = 0.25). CONCLUSIONS: POCI following major thoracic and abdominopelvic surgery occurred in 1.83% of this cohort and was associated with substantially higher in-hospital mortality and higher 1-year all-cause mortality. These findings provide a population-specific incidence benchmark and support structured preoperative cardiovascular risk review, rather than reliance on inflammatory indices or machine-learning scores, whose positive predictive values are limited in this low-prevalence setting.