Platelet Decreases following Continuous Renal Replacement Therapy Initiation as a Novel Risk Factor for Renal Nonrecovery

Abstract

Background: Continuous renal replacement therapy (CRRT) is a form of dialysis used in critically ill patients, and has recently been associated with renal nonrecovery. Decreases in platelets following CRRT initiation are common and are associated with mortality, but associations with renal recovery are unclear. Our objective was to determine if platelet nadir or the degree of platelet decrease following CRRT initiation was associated with renal nonrecovery. Methods: This is a secondary analysis of the Randomized Evaluation of Normal versus Augmented Level (RENAL) trial. Primary predictors were platelet nadir discretized by median value and percent platelet decrease following CRRT initiation, with cut points evaluated by decile from 30 to 60%. The 2 primary outcomes were time to RRT-independence and RRT-free days. Secondary outcomes were 28-day mortality, 90-day mortality, intensive care unit (ICU)-free, and hospital-free days. Results: Time to RRT independence censored for death was achieved less frequently in patients with low platelet nadir (hazard ratio [HR] 0.77, confidence interval [CI] 0.66–0.91) and in those with >50% platelet decrease (HR 0.84, CI 0.72–0.97). RRT-free days were lower in both low platelet nadir (odds ratio [OR] 0.94, CI 0.90–0.97) and >50% platelet decrease (OR 0.91, CI 0.88–0.95). These groups also had higher rates of 28- and 90-day mortality and fewer ICU-free and hospital-free days. Thrombocytopenia at CRRT initiation was also associated with renal nonrecovery, although the clinical effect was small. Conclusions: Platelet nadir <100 × 10³/µL and platelet decrease by >50% following CRRT initiation were both associated with lower rates of renal recovery. Further research is needed to evaluate mechanisms-linking platelet changes and renal nonrecovery in CRRT.