Implementation of a new definition for acute kidney injury in the National Surgical Quality Improvement Project: What is the impact?

Published:January 06, 2023DOI:



      The National Surgical Quality Improvement Project is the preeminent surgical quality database, but it undercaptures acute kidney injury. Recently, the National Surgical Quality Improvement Project lowered the thresholds for acute kidney injury for the first time, so we assessed the impact of implementing the definition change on the rate of acute kidney injuries.


      For this interrupted time series analysis, we assembled 2 institutional National Surgical Quality Improvement Project files to identify adults undergoing inpatient noncardiac nonvascular surgery. The acute kidney injury definition changed on July 1, 2021, so patients were stratified by their operative date into 12-month pre and post groups. Weighted covariate propensity score matching and logistic regression were used to balance the periods and compare outcomes.


      In total, 4,784 adults were eligible (55% pre and 45% post change). The overall rate of postoperative outcomes was similar, aside for acute kidney injury (pre 0.3%, post 5.6%, P < .0001). Regardless of the period, patients with acute kidney injuries had significantly longer lengths of stay and morbidity and mortality rates compared to those without an acute kidney injury. After the definition change, 81% of acute kidney injuries were stage I, and none were identified by urine output alone. After matching, surgery after the definition change was associated with an increased weighted odds of an acute kidney injury compared to surgery before the change (odds ratio 26.2; 95% confidence interval, 12.1–56.8).


      In the year after the definition change, there was a 1,700% relative increase in the rate of reported acute kidney injuries. Newly identified acute kidney injuries are associated with high complication rates, and this definition change has implications for patient counseling, research, and quality reporting.
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        • Karaca Z.
        • McDermott K.W.
        High-volume invasive, therapeutic ambulatory surgeries performed in hospital-owned facilities, 2016.
        (2020. Accessed 5 September 2022)
        • Steiner C.A.
        • Karaca Z.
        • Moore B.J.
        • Imshaug M.C.
        • Pickens G.
        Surgeries in hospital-based ambulatory surgery and hospital inpatient settings, 2014.
        (2020. Accessed 5 September 2022)
        • Thakar C.V.
        Perioperative acute kidney injury.
        Adv Chronic Kidney Dis. 2013; 20: 67-75
        • Kheterpal S.
        • Tremper K.K.
        • Heung M.
        • et al.
        Development and validation of an acute kidney injury risk index for patients undergoing general surgery: results from a national data set.
        Anesthesiology. 2009; 110: 505-515
        • Hobson C.
        • Ozrazgat-Baslanti T.
        • Kuxhausen A.
        • et al.
        Cost and mortality associated with postoperative acute kidney injury.
        Ann Surg. 2015; 261: 1207-1214
        • Silver S.A.
        • Chertow G.M.
        The economic consequences of acute kidney injury.
        Nephron. 2017; 137: 297-301
        • Boyer N.
        • Eldridge J.
        • Prowle J.R.
        • Forni L.G.
        Postoperative AKI.
        Clin J Am Soc Nephrol. 2022; 17: 1535-1545
        • Kellum J.A.
        • Romagnani P.
        • Ashuntantang G.
        • Ronco C.
        • Zarbock A.
        • Anders H.J.
        Acute kidney injury.
        Nat Rev Dis Primers. 2021; 7: 52
      1. ACS NSQIP Participant Use Data File.
        (Accessed 5 September 2022)
        • Bihorac A.
        • Brennan M.
        • Ozrazgat-Baslanti T.
        • et al.
        National surgical quality improvement program underestimates the risk associated with mild and moderate postoperative acute kidney injury.
        Crit Care Med. 2013; 41: 2570-2583
        • Levey A.S.
        Measurement of renal function in chronic renal disease.
        Kidney Int. 1990; 38: 167-184
        • Bihorac A.
        • Yavas S.
        • Subbiah S.
        • et al.
        Long-term risk of mortality and acute kidney injury during hospitalization after major surgery.
        Ann Surg. 2009; 249: 851-858
        • Prowle J.R.
        • Forni L.G.
        • Bell M.
        • et al.
        Postoperative acute kidney injury in adult non-cardiac surgery: joint consensus report of the Acute Disease Quality Initiative and PeriOperative Quality Initiative.
        Nat Rev Nephrol. 2021; 17: 605-618
        • Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury Work Group
        KDIGO clinical practice guideline for acute kidney injury.
        Kidney Int Suppl. 2012; 2: 1-138
        • Inker L.A.
        • Eneanya N.D.
        • Coresh J.
        • et al.
        Chronic Kidney Disease Epidemiology Collaboration. New creatinine- and cystatin C-based equations to estimate GFR without race.
        N Engl J Med. 2021; 385: 1737-1749
        • von Elm E.
        • Altman D.G.
        • Egger M.
        • Pocock S.J.
        • Gøtzsche P.C.
        • Vandenbroucke J.P.
        • STROBE Initiative
        The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies.
        J Clin Epidemiol. 2008; 61: 344-349
        • Chesnaye N.C.
        • Stel V.S.
        • Tripepi G.
        • et al.
        An introduction to inverse probability of treatment weighting in observational research.
        Clin Kidney J. 2021; 15: 14-20
        • Desai R.J.
        • Franklin J.M.
        Alternative approaches for confounding adjustment in observational studies using weighting based on the propensity score: a primer for practitioners.
        BMJ. 2019; 367: l5657
        • Linden A.
        • Adams J.L.
        Applying a propensity score-based weighting model to interrupted time series data: improving causal inference in programme evaluation.
        J Eval Clin Pract. 2011; 17: 1231-1238
        • Hilmi I.A.
        • Damian D.
        • Al-Khafaji A.
        • et al.
        Acute kidney injury following orthotopic liver transplantation: incidence, risk factors, and effects on patient and graft outcomes.
        Br J Anaesth. 2015; 114: 919-926
        • Loria A.
        • Fleming F.J.
        Postoperative acute kidney injury in colorectal surgery.
        Dis Colon Rectum. 2022; 65: 308-312
        • Slagelse C.
        • Gammelager H.
        • Iversen L.H.
        • Sørensen H.T.
        • Christiansen C.F.
        Acute kidney injury and 1-year mortality after colorectal cancer surgery: a population-based cohort study.
        BMJ Open. 2019; 9e024817
        • Thakar C.V.
        • Kharat V.
        • Blanck S.
        • Leonard A.C.
        Acute kidney injury after gastric bypass surgery.
        Clin J Am Soc Nephrol. 2007; 2: 426-430
        • Loria A.
        • Melucci A.
        • Speranza J.
        • et al.
        Acute kidney injury is a common and significant complication following ileostomy formation.
        Colorectal Dis. 2022; 24: 102-110
        • O’Connor M.E.
        • Hewson R.W.
        • Kirwan C.J.
        • Ackland G.L.
        • Pearse R.M.
        • Prowle J.R.
        Acute kidney injury and mortality 1 year after major non-cardiac surgery.
        Br J Surg. 2017; 104: 868-876
        • Hobson C.
        • Lysak N.
        • Huber M.
        • Scali S.
        • Bihorac A.
        Epidemiology, outcomes, and management of acute kidney injury in the vascular surgery patient.
        J Vasc Surg. 2018; 68: 916-928
        • Gameiro J.
        • Fonseca J.A.
        • Marques F.
        • Lopes J.A.
        Management of acute kidney injury following major abdominal surgery: a contemporary review.
        J Clin Med. 2020; 9: 2679