Aims Cardiac surgery (CS) can induce an inflammatory response (IR) that is associated with poorer outcomes. Immature platelets are among the factors that may be associated with IR development. We aimed to evaluate whether immature platelet fraction (IPF) could be a predictive biomarker for IR and whether IPF could improve the prognosis assessment of IR for Acute Physiologic and Chronic Health Evaluation (APACHE II) and Sequential Organ Failure Assessment (SOFA) following CS.

Methods Three-hundred and twenty-seven (327) patients who underwent CS were enrolled during the study period. IR was defined according to the need for vasopressor support (>48 hours). Perioperative variables and outcomes were registered in our database. IPF was measured immediately following CS and at 24 hours by Sysmex XN analyzer and the difference between both measurements (ΔIPF) was calculated. To assess the relationship between ΔIPF and IR, univariate and multivariate logistic regression were performed. To analyse the additive value of ΔIPF in APACHE II and SOFA scores in predicting IR, an area under the receiver operating characteristic (AUROC) curve was calculated.

Results Among 327 patients included, 60 patients (18.3%) developed IR. Multivariate analysis showed ΔIPF was significantly associated with IR (OR: 1.26; 95% CI: 1.01 to 1.56; p=0.038). The combination of ΔIPF with scores improved the AUROC for IR prediction: 0.629 vs 0.728 (p=0.010) for APACHE II and 0.676 vs 0.715 (p=0.106) for SOFA.

Conclusion These findings suggested that ΔIPF may be a useful and low-cost biomarker for the early identification of patients at risk of IR development.