Association of C-Reactive Protein with Functional Outcome After Acute Ischemic Stroke Across TOAST Subtypes

Background/Objectives: Elevated C-reactive protein (CRP) has been associated with adverse outcomes after acute ischemic stroke (AIS), but whether the association differs by stroke etiology remains uncertain. We evaluated elevated CRP in relation to 3-month functional outcome across Trial of Org 10172 in Acute Stroke Treatment (TOAST) subtypes. Methods: This retrospective study included 2975 consecutive patients with AIS from a stroke registry. Elevated CRP was defined as ≥3 mg/L, and the primary outcome was an unfavorable 3-month modified Rankin Scale (mRS) score of 2-6. Multivariable logistic regression was performed overall and within TOAST subtypes. Sensitivity analyses used raw NIHSS, continuous CRP, alternative CRP thresholds, an alternative mRS cutoff, and formal CRP×TOAST interaction testing. Results: Overall, 1464 patients (49.2%) had an unfavorable outcome. In the prespecified model, elevated CRP was associated with an unfavorable outcome overall (adjusted odds ratio [aOR], 1.301; 95% confidence interval [CI], 1.003-1.687; p = 0.047) and in the small-vessel occlusion (SVO) subgroup (aOR, 2.620; 95% CI, 1.094-6.275; p = 0.031). However, the all-category CRP×TOAST interaction was not significant (P_interaction = 0.154). With nonlinear adjustment for raw NIHSS, the SVO association was attenuated (aOR, 2.243; 95% CI, 0.899-5.598; p = 0.083), and the interaction remained nonsignificant (P_interaction = 0.317). Conclusions: Higher CRP was associated with unfavorable functional outcome, but the findings did not establish a TOAST subtype-specific association.