Background The burden of acute kidney injury (AKI) in the paediatric age group is unknown, partly due to the lack of a universally agreed definition in the past. The aim of this study was to assess the point incidence of AKI among hospitalised children on World Kidney Day 2016.

Methods Cross-sectional study involving tertiary paediatric centres across the United Kingdom. Centres reported new cases of AKI on a single observation day. Associated clinical features and follow-up data were recorded. AKI was defined according to the KDIGO (Kidney Disease: Improving Global Outcomes) classification.

Results On the observation day, there were 1218 inpatients in 8 centres. 31 children (2.5%) met the case definition for AKI. The majority of patients had no pre-existing, known risk factors for AKI (20/31, 65%), while the leading known risk factor was congenital heart disease (5/31, 15%). Most cases of AKI were hospital acquired (21/31, 68%). The leading acute contributory factors were: medications (13/31, 42%), hypotension/shock (10/31, 32%) and dehydration (10/31, 32%). AKI was subdivided according to severity: stage 1 (24/31, 78%), stage 2 (2/31, 6%) and stage 3 (5/31, 16%). All 31 cases had 7 day follow-up data. Renal replacement therapy was required in 2 cases (6%). Recovery from AKI at 7 days was: complete (18/31, 58%), incomplete (9/31, 29%) or unknown (4/31, 13%); 2 patients (6%) died from non-renal causes.

Discussion and Conclusion This is the first study looking at the point incidence of AKI in hospitalised paediatric patients in the UK, according to the KDIGO classification. Our point incidence of 2.5% is similar to international reports. The majority of cases were hospital acquired and due to nephrotoxic medications, a significant modifiable factor. Prospective studies are necessary to evaluate the benefit of interventions designed to reduce the incidence of AKI in children.