Prevalence, Risk Factors and Outcomes of Platelet Transfusion Refractoriness in Critically Ill Patients:  A Retrospective Cohort Study

Abstract Background: Refractoriness to platelet transfusion is an understudied phenomenon in critically ill patients. Our objective was to evaluate the prevalence, risk factors and clinical outcomes of platelet refractoriness among patients in a tertiary-care intensive care unit (ICU).Methods: A retrospective cohort study included all patients (age >14 years) who were admitted to a tertiary-care medical-surgical ICU between 2011 and 2016 and received ≥2 platelet transfusions during their ICU stay. We calculated platelet increment (PI) and corrected count increment (CCI). Results: A total of 267 patients were enrolled in the study, collectively receiving 1357 transfusions with a median of 3 (interquartile range: 2-6) transfusions per patient. The median pretransfusion platelet count was 31.0 x109/L (interquartile range: 16.0, 50.0) with a median PI of 6 x109/L (interquartile range: -5, 24). The prevalence of platelet transfusion refractoriness was 54.8% based on PI and 57.0% based on CCI. The two methods had excellent concordance in diagnosing refractoriness (kappa coefficient: 0.939). Refractoriness was more common in patients admitted by Hepatology, Liver Transplant, and Hematology services (69.7%, 69.2%, and 55.6%, respectively). On multivariable logistic regression, younger age was the only significant predictor of refractoriness (odds ratio per year increment: 0.975, 95% CI: 0.951-0.999). Finally, refractoriness was associated with increased length of stay in the ICU (p=0.02), but not with mortality.Conclusions: We demonstrated excellent concordance between PI and CCI for the diagnosis of platelet transfusion refractoriness. Platelet transfusion refractoriness was highly (>50%) prevalent in critically ill patients. However, it was not associated with increased mortality.