Associations of inflammation-related nutritional and metabolic status indices CAR and CTI with 90-day unfavorable functional outcomes in patients with acute ischemic stroke

Background Composite indices integrating inflammation, nutritional reserve, and metabolic status may improve early prognostic assessment after acute ischemic stroke (AIS). This study examined the associations of the C-reactive protein-to-albumin ratio (CAR) and the CRP–triglyceride–glucose index (CTI) with 90-day functional outcomes. Methods A Korean single-center stroke registry (2010–2016) was analyzed ( n = 1,484). CAR and CTI were calculated from admission laboratory tests. The primary endpoint was 90-day unfavorable functional outcome defined as modified Rankin Scale 3–6. Associations were examined using multivariable logistic regression with standardized exposures; restricted cubic splines assessed non-linearity. Prognostic performance was evaluated using receiver operating characteristic analysis and a parsimonious model derived with penalized regression. Internal validation was performed using repeated 10-fold cross-validation, and model calibration was assessed using a calibration plot, calibration intercept, calibration slope, and Brier score. Results Unfavorable outcomes occurred in 414 patients (27.9%). After full adjustment, higher CAR (OR 1.25, 95% CI 1.09–1.43) and higher CTI (OR 1.38, 95% CI 1.19–1.60) were independently associated with unfavorable outcome. CTI showed an approximately linear risk gradient, whereas CAR showed evidence of a non-linear association. As single predictors, CAR and CTI yielded AUCs of 0.656 and 0.651 and outperformed albumin, triglycerides, and fasting plasma glucose. A six-variable model including sex, age, body mass index, admission NIHSS, CAR, and CTI achieved an apparent AUC of 0.837. Internal validation showed stable performance, with a mean cross-validated AUC of 0.831, mean Brier score of 0.142, calibration intercept of 0.023, and calibration slope of 1.018. Conclusion CAR and CTI, derived from routine admission laboratory tests, were associated with 90-day functional outcomes after acute ischemic stroke and may aid early prognostic assessment. The derived six-variable model showed acceptable internal performance, but should be considered exploratory pending external validation.