INTERNATIONAL PROSPECTIVE MULTICENTRE INITIATIVE ON POSTOPERATIVE ACUTE KIDNEY INJURY IN CHILDREN AFTER NONCARDIAC SURGERY ( POAKIDS)

Postoperative acute kidney injury (PO-AKI) is a frequent yet underdignosticated complication in adults, but remains poorly characterized in children undergoing noncardiac surgery. Most available data in paediatrics derive from small, retrospective single-centre series, often using non-uniform definitions. No large prospective study has yet systematically investigated the epidemiology, risk factors, and biomarker of PO-AKI in this population. The POAKIDS (Post-Operative Acute Kidney Injury in Children after noncardiac Surgery) initiative was established to fill this knowledge gap by creating an international collaborative network focused on standardized data and sample collection in hospitalized paediatric patients.

POAKIDS is an international, prospective, observational multicentre study coordinated by Uppsala University and the IRCCS Giannina Gaslini Institute. Children aged 0–16 years undergoing non-ambulatory noncardiac surgery under general anaesthesia are enrolled after informed consent. The diagnosis of PO-AKI follows the KDIGO-creatinine criteria, based on paired pre- and postoperative plasma creatinine (baseline and 12–36 h after surgery). Plasma cystatin-C is also measured for comparison. Urine samples are obtained perioperatively and analysed for a broad panel of biomarkers reflecting glomerular and tubular injury (NGAL, KIM-1, TIMP-2, IGFBP-7, S100A8, OPG, Galectin-3, Cystatin-C, and albumin). Clinical, anaesthetic, and intraoperative variables are prospectively recorded in a secure REDCap database hosted at Uppsala University. Local laboratories perform routine biochemical analyses, while urinary biomarkers are batch-analysed in Uppsala and proteomic profiling is conducted in Genova. The planned sample size of 2,000 patients ensures a 1% precision margin for an expected 4–5% PO-AKI incidence. However, the expanding network and current recruitment indicate that this threshold will likely be surpassed.

Recruitment began in 2024 and is progressing across several European tertiary centres, including Sweden, Italy, Switzerland, Brazil, Australia. Preliminary feasibility assessments confirmed high adherence to data entry, timely biosample processing, and excellent cross-centre coordination. The shared electronic infrastructure and harmonized biobanking procedures have proven effective in maintaining data integrity across sites. Early analyses indicate that POAKIDS is well positioned to deliver the first reliable estimate of paediatric PO-AKI incidence and to explore the diagnostic value of urinary biomarkers in a real-world, heterogeneous surgical cohort. The project has already attracted additional international interest, supporting the expansion of the network beyond Europe.

POAKIDS represents the first coordinated, prospective, multicentre effort to characterize PO-AKI in children after noncardiac surgery using standardized diagnostic criteria and centralized biomarker analysis. The study will provide novel insights into the epidemiology and mechanisms of perioperative kidney damage, ultimately guiding the development of early diagnostic tools and preventive strategies. By combining clinical expertise from leading paediatric anaesthesia and nephrology centres, POAKIDS establishes a durable platform for future collaborative research on kidney protection in children worldwide.