Interaction analysis of CONUT score and NLR in predicting functional outcomes after mechanical thrombectomy

Abstract

Background: This study investigates the prognostic value of the Controlling Nutritional Status (CONUT) score and its relationship with systemic inflammation, measured by the Neutrophil-to- Lymphocyte Ratio (NLR), in patients with acute ischemic stroke (AIS) treated with mechanical thrombectomy (MT). Specifically, we aimed to determine whether NLR acts as a mediator or an effect modifier in the relationship between malnutrition and poor outcomes.

Methods: This retrospective cohort study analyzed 470 AIS patients undergoing MT. Malnutrition was assessed by the CONUT score, and inflammation was evaluated by NLR upon admission. These assessments were used to investigate their association with the primary outcome, which was poor functional status defined as modified Rankin Scale scores 3 to 6 at 90 days. Multivariable logistic regression, interaction analysis, and exploratory mediation analysis were performed to explore the relationships between malnutrition, inflammation, and functional outcomes.

Results: Of 470 patients, 57.2% had poor outcomes. The CONUT score was identified as a robust independent predictor of poor prognosis (OR = 1.66, 95% CI: 1.43–1.93, P < 0.001). Mediation analysis revealed that NLR did not significantly mediate the effect of the CONUT score on patient outcomes (P > 0.05). However, a significant synergistic interaction was observed between the CONUT score and NLR (P for interaction = 0.034). Specifically, the risk of poor outcome associated with higher CONUT scores was markedly greater in patients with high inflammatory levels compared to those with low inflammatory levels. Adding CONUT significantly improved the predictive accuracy of the baseline model, with the AUC increasing from 0.785 to 0.842 (P < 0.001).

Conclusions: Malnutrition (high CONUT score) is a strong predictor of poor outcomes after MT. Importantly, systemic inflammation modifies rather than mediates this risk, meaning that it influences the severity of risk without being the direct cause, which supports a synergistic double-hit effect in which malnutrition and inflammation jointly exacerbate patient outcomes. Joint assessment of immuno- nutritional status helps identify high-risk patients who may benefit from intensive management.