Acute kidney injury in the UK: a replication cohort study of the variation across three regional populations

Simon Sawhney*, Heather A. Robinson, Sabine N. Van der Veer, Hilda O. Hounkpatin, Timothy M. Scale, James A. Chess, Niels Peek, Angharad Marks, Gareth Ivor Davies, Paolo Fraccaro, Matthew J. Johnson, Ronan A. Lyons, Dorothea Nitsch, Paul J. Roderick, Nynke Halbesma, Eve Miller-Hodges, Corrinda Black, Simon Fraser

*Corresponding author for this work

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Objectives A rapid growth in the reported rates of acute kidney injury (AKI) has led to calls for greater attention and greater resources for improving care. However, the reported incidence of AKI also varies more than tenfold between previous studies. Some of this variation is likely to stem from methodological heterogeneity. This study explores the extent of cross-population variation in AKI incidence after minimising heterogeneity. Design Population-based cohort study analysing data from electronic health records from three regions in the UK through shared analysis code and harmonised methodology. Setting Three populations from Scotland, Wales and England covering three time periods: Grampian 2003, 2007 and 2012; Swansea 2007; and Salford 2012. Participants All residents in each region, aged 15 years or older. Main outcome measures Population incidence of AKI and AKI phenotype (severity, recovery, recurrence). Determined using shared biochemistry-based AKI episode code and standardised by age and sex. Results Respectively, crude AKI rates (per 10 000/year) were 131, 138, 139, 151 and 124 (p=0.095), and after standardisation for age and sex: 147, 151, 146, 146 and 142 (p=0.257) for Grampian 2003, 2007 and 2012; Swansea 2007; and Salford 2012. The pattern of variation in crude rates was robust to any modifications of the AKI definition. Across all populations and time periods, AKI rates increased substantially with age from ~20 to ~550 per 10 000/year among those aged <40 and ≥70 years. Conclusion When harmonised methods are used and age and sex differences are accounted for, a similar high burden of AKI is consistently observed across different populations and time periods (~150 per 10 000/year). There are particularly high rates of AKI among older people. Policy-makers should be careful not draw simplistic assumptions about variation in AKI rates based on comparisons that are not rigorous in methodological terms.
Original languageEnglish
Article numbere019435
Number of pages12
JournalBMJ Open
Issue number6
Early online date30 Jun 2018
Publication statusPublished - 30 Jun 2018

Bibliographical note

This work was funded by a grant from the UK’s Farr Institute for Health
Informatics Research (UKHIRN/XFarrRP001). The Farr Institute is supported by a
10-funder consortium: Arthritis Research UK, the British Heart Foundation, Cancer Research UK, the Economic and Social Research Council, the Engineering and Physical Sciences Research Council, the Medical Research Council, the National Institute of Health Research, the National Institute for Social Care and Health Research (Welsh Assembly Government), the Chief Scientist Office (Scottish Government Health Directorates) and the Wellcome (MRC grant nos. CIPHER MR/K006525/1, HeRC MR/K006665/1, London MR/ K006584/1, Scotland MR/K007017/1). We also acknowledge the data management support of Grampian Data Safe Haven (DaSH) and the associated financial support of NHS Research Scotland, through NHS Grampian investment in the Grampian DaSH. Work on this project was also part funded by Health Care and Research Wales, and by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care Wessex at Southampton NHS Hospitals Foundation Trust. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. SS was supported by a research training fellowship from the Wellcome Trust to study the outcomes of acute kidney injury (WT102729/Z/13/Z).


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