Risk of postoperative acute kidney injury in patients undergoing orthopaedic surgery—development and validation of a risk score and effect of acute kidney injury on survival: observational cohort study
BMJ 2015; 351 doi: https://doi.org/10.1136/bmj.h5639 (Published 11 November 2015) Cite this as: BMJ 2015;351:h5639- Samira Bell, consultant nephrologist1,
- Friedo W Dekker, professor of clinical epidemiology2,
- Thenmalar Vadiveloo, statistician3,
- Charis Marwick, senior clinical academic fellow3,
- Harshal Deshmukh, specialty registrar3,
- Peter T Donnan, professor of epidemiology and biostatistics3,
- Merel Van Diepen, postdoctoral epidemiologist2
- 1Renal Unit, Ninewells Hospital, NHS Tayside, Dundee DD1 9SY, UK
- 2Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden, Netherlands
- 3 Division of Population Health Sciences , School of Medicine, University of Dundee, Dundee, UK
- Correspondence to: S Bell samira.bell{at}nhs.net
- Accepted 9 October 2015
Abstract
Study question What is the predicted risk of acute kidney injury after orthopaedic surgery and does it affect short term and long term survival?
Methods The cohort comprised adults resident in the National Health Service Tayside region of Scotland who underwent orthopaedic surgery from 1 January 2005 to 31 December 2011. The model was developed in 6220 patients (two hospitals) and externally validated in 4395 patients from a third hospital. Several preoperative variables were selected for candidate predictors, based on literature, clinical expertise, and availability in the orthopaedic surgery setting. The main outcomes were the development of any severity of acute kidney injury (stages 1-3) within the first postoperative week, and 90 day, one year, and longer term survival.
Study answer and limitations Using logistic regression analysis, independent predictors of acute kidney injury were older age, male sex, diabetes, number of prescribed drugs, lower estimated glomerular filtration rate, use of angiotensin converting enzyme inhibitors or angiotensin receptor blockers, and American Society of Anesthesiologists grade. The model’s predictive performance for discrimination was good (C statistic 0.74 in development cohort, 0.70 in validation cohort). Calibration was good in the development cohort and after recalibration in the validation cohort. Only the highest risks were over-predicted. Survival was worse in patients with acute kidney injury compared with those without (adjusted hazard ratio 1.53, 95% confidence interval 1.38 to 1.70). This was most noticeable in the short term (adjusted hazard ratio: 90 day 2.36, 1.94 to 2.87) and diminished over time (90 day-one year 1.40, 1.10 to 1.79; >1 year 1.28, 1.10 to 1.48). The model used routinely collected data in the orthopaedic surgery setting therefore some variables that could potentially improve predictive performance were not available. However, the readily available predictors make the model easily applicable.
What this study adds A preoperative risk prediction model consisting of seven predictors for acute kidney injury was developed, with good predictive performance in patients undergoing orthopaedic surgery. Survival was significantly poorer in patients even with mild (stage 1) postoperative acute kidney injury.
Funding, competing interests, data sharing SB received grants from Tenovus Tayside, Chief Scientist Office, and the Royal College of Physicians and Surgeons of Glasgow; PT receives grants from Novo Nordisk, GlaxoSmithKline, and the New Drugs Committee of the Scottish Medicines Consortium. No additional data are available.
Footnotes
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Contributors: SB, CM, and PTD conceived the study. SB, MVD, PTD, and FD designed the study. TV, SB, HD, MVD, and PTD acquired and analysed the data. All authors revised the paper critically for important intellectual content and approved the final version of the manuscript; had full access to the data (including statistical reports and tables) in the study; and take responsibility for the integrity of the data and the accuracy of the data analysis. MVD is guarantor for the study.
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Funding: This study was funded by Tenovus Tayside, Chief Scientist Office, Scotland and a travelling fellowship from the Royal College of Physicians and Surgeons of Glasgow. The funders had no role in the study design; collection, analysis, and interpretation of the data; writing of the report; or the decision to submit the article for publication. The researchers are independent of the funders.
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Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: PT receives grants from Novo Nordisk, GlaxoSmithKline, and the New Drugs Committee of the Scottish Medicines Consortium, outside the submitted work; no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years no other relationships or activities that could appear to have influenced the submitted work.
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Data sharing: No additional data available.
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Transparency: The manuscript’s guarantor (MVD) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
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