Definition of hourly urine output influences reported incidence and staging of acute kidney injury

Allen, Jennifer C.; Gardner, David S.; Skinner, Henry; Harvey, Daniel; Sharman, Andrew; Devonald, Mark A.J.

Abstract

© 2020 The Author(s). Background: Acute kidney injury (AKI) is commonly defined using the KDIGO system, which includes criteria based on reduced urine output (UO). There is no consensus on whether UO should be measured using consecutive hourly readings or mean output. This makes KDIGO UO definition and staging of AKI vulnerable to inconsistency which has implications both for research and clinical practice. The objective of this study was to investigate whether the way in which UO is defined affects incidence and staging of AKI. Methods: We conducted a retrospective analysis of two single centre observational studies investigating (i) patients undergoing cardiac surgery and (ii) patients admitted to general intensive care units (ICU). AKI was identified using KDIGO serum creatinine (SCr) criteria and two methods of UO (UOcons: UO meeting KDIGO criteria in each consecutive hour; UOmean: Mean hourly UO meeting KDIGO criteria). Results: Data from 151 CICU and 150 ICU admissions were analysed. Incidence of AKI using SCr alone was 23.8% in CICU and 32% in ICU. Incidence increased in both groups when UO was considered, with inclusion of UOmean more than doubling reported incidence of AKI (CICU: UOcons 39.7%, UOmean 72.8%; ICU: UOcons 51.3%, UOmean 69.3%). In both groups UOcons led to a larger increase in KDIGO stage 1 but UOmean increased the incidence of KDIGO stage 2. Conclusions: We demonstrate a serious lack of clarity in the internationally accepted AKI definition leading to significant variability in reporting of AKI incidence.

Citation

Allen, J. C., Gardner, D. S., Skinner, H., Harvey, D., Sharman, A., & Devonald, M. A. (2020). Definition of hourly urine output influences reported incidence and staging of acute kidney injury. BMC Nephrology, 21(1), Article 19. https://doi.org/10.1186/s12882-019-1678-2

• Journal Article Type: Article
• Acceptance Date: Dec 30, 2019
• Online Publication Date: Jan 15, 2020
• Publication Date: Jan 15, 2020
• Deposit Date: Jan 9, 2020
• Publicly Available Date: Jan 9, 2020
• Journal: BMC Nephrology
• Electronic ISSN: 1471-2369
• Publisher: Springer Verlag
• Peer Reviewed: Peer Reviewed
• Volume: 21
• Issue: 1
• Article Number: 19
• DOI: https://doi.org/10.1186/s12882-019-1678-2
• Keywords: Acute kidney injury; Urine output; Cardiac surgery; Intensive care; KDIGO
• Public URL: https://nottingham-repository.worktribe.com/output/3695826
• Publisher URL: https://link.springer.com/article/10.1186/s12882-019-1678-2
• Additional Information: Received: 19 May 2019; Accepted: 30 December 2019; First Online: 15 January 2020; : Ethics approval for the 2 studies was granted by the NHS Health Research Authority Research Ethics Committee East Midlands - Nottingham 1, references CitationRef removed/EM/0451 and 15/EM/0452. Written consent was obtained from all participants with capacity to provide it. REC gave permission to recruit patients lacking capacity after discussion with the patient’s consultee.; : Not applicable.; : The authors declare that they have no competing interests.