Hypophosphatemia in Pediatric Patients on Continuous Kidney Replacement Therapy-A WE-ROCK Study.

Background: Hypophosphatemia is common during critical illness and in patients receiving continuous kidney replacement therapy (CKRT). In this secondary analysis of an international multicenter study, we aimed to evaluate the incidence of hypophosphatemia, associated outcomes, and impact of phosphate-containing CKRT fluids. Methods: We conducted a multicenter retrospective cohort study of patient < 25 years from the Worldwide Exploration of Renal Replacement Outcomes Collaborative in Kidney Disease (WE-ROCK) who underwent CKRT for acute kidney injury and pathologic fluid accumulation. Hypophosphatemia was defined as serum phosphate < 2.5 mg/dL during the first 7 days of CKRT. Patients were categorized by CKRT fluid type: phosphate-containing (PHOS+) commercial, PHOS+ compounded, or phosphate-free (PHOS-); those who received > 1 fluid type were excluded. Outcomes included 28-day ventilator-, ICU-, and hospital-free days, and ICU and 90-day mortality. Results: We included 823 patients with a median age of 9.0 years (IQR 1.7-15.3). The majority received PHOS+ fluids (69%; 572/823). The overall incidence of hypophosphatemia was 31% (257/823 patients), occurring more frequently in those receiving PHOS- (91/251, 36%) compared to PHOS+ fluids (166/572, 29%). On adjusted analysis, commercial PHOS+ fluids had lower odds of developing hypophosphatemia than PHOS- fluids (OR 0.62, 95% CI 0.40-0.96; p = 0.03). Hypophosphatemia was not associated with ventilator-, ICU-, or hospital-free days, or mortality after adjusting for confounders. Conclusions: Hypophosphatemia occurred in approximately one-third of pediatric patients receiving CKRT. Use of PHOS+ CKRT fluids, particularly commercial formulations, was independently associated with a lower incidence of hypophosphatemia, identifying CKRT fluid selection as a potential modifiable practice.