Prognostic value of blood interleukin-6 in the prediction of functional outcome after stroke: A systematic review and meta-analysis

•The association between IL-6 and stroke outcome was quantified by meta-analysis.•We retrieved individual data from 20 studies including 4,112 stroke patients.•IL-6 was independently associated with poor outcome and post-stroke infection.•Addition of IL-6 to predictive clinical models slightly improved its prediction.•Isolated IL-6 determination in stroke seems not useful for outcome prediction.

We aimed to quantify the association of blood interleukin-6 (IL-6) concentrations with poor outcome after stroke and its added predictive value over clinical information. Meta-analysis of 24 studies confirmed this association with a weighted mean difference of 3.443 (1.592-5.294) pg/mL, despite high heterogeneity and publication bias. Individual participant data including 4112 stroke patients showed standardized IL-6 levels in the 4th quartile were independently associated with poor outcome (OR = 2.346 (1.814-3.033), p < 0.0001). However, the additional predictive value of IL-6 was moderate (IDI = 1.5%, NRI = 5.35%). Overall these results indicate an unlikely translation of IL-6 into clinical practice for this purpose.

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