Thrombocytopenia in Children and Young Adults Undergoing Continuous Renal Replacement Therapy: A WE-ROCK Study

Introduction: Thrombocytopenia in patients treated with continuous renal replacement therapy (CRRT) in adults is associated with mortality. Pediatric data are limited. The association between pre-CRRT thrombocytopenia and platelet decline at 24 h of CRRT with outcomes was evaluated. Methods: Secondary analysis of the Worldwide Exploration of Renal Replacement Outcomes Collaborative in Kidney Disease (WE-ROCK) includes patients' birth-25 years who underwent CRRT. Exclusions were end-stage kidney disease, non-acute kidney injury/fluid overload CRRT indication, concurrent extracorporeal membrane oxygenation, missing baseline platelets, platelet disorders, and hematologic malignancy. Primary exposures were (i) pre-CRRT thrombocytopenia (≤100 × 103/μL) and (ii) ≥30% decline at 24 h of CRRT in those with pre-CRRT >100 × 103/μL. Primary outcome was survival to intensive care unit (ICU) discharge. Secondary outcomes included major adverse kidney events at 90 days (MAKE-90) (death, dialysis dependence, creatinine >125% baseline) from CRRT initiation. Results: A total of 805 patients were included. Overall, 63.9% had baseline thrombocytopenia, median (IQR) platelets of 38 (20, 63) ×103/μL. Baseline thrombocytopenia occurred in younger septic patients with higher illness severity. A ≥30% decline occurred in 33% of patients. Those with a ≥30% platelet decline were more commonly younger patients and had smaller catheters. Pre-CRRT thrombocytopenia and platelet decline were associated with ICU mortality in univariate but not multivariate models. There was no association with MAKE- 90. Conclusions: Thrombocytopenia is common prior to CRRT initiation and is associated with greater illness severity. These findings stress the importance of vigilant monitoring of platelet levels before CRRT initiation and during therapy as thrombocytopenia at both time points may be a prognostic indicator. Additionally, this study highlights the need for future research to clarify the interplay of patient and mechanical factors in this phenomenon and guide potential interventions.