Cystatin C or creatinine for pre-operative assessment of kidney function and risk of post-operative acute kidney injury: a secondary analysis of the METS cohort study
Authors: Prowle John R , Croal Bernard , Abbott Thomas E F , Cuthbertson Brian H , Wijeysundera Duminda N ,   for the METS study investigators, Myles P S , Shulman M A , Wallace S , Farrington C , Thompson B , Ellis M , Borg B , Kerridge R K , Douglas J , Brannan J , Pretto J , Godsall M G , Beauchamp N , Allen S , Kennedy A , Wright E , Malherbe J , Ismail H , Riedel B , Melville A , Sivakumar H , Murmane A , Kenchington K , Kirabiyik Y , Gurunathan U , Stonell C , Brunello K , Steele K , Tronstad O , Masel P , Dent A , Smith E , Bodger A , Abolfathi M , Sivalingam P , Hall A , Painter T W , Macklin S , Elliott A , Carrera A M , Terblanche N C S , Pitt S , Samuels J , Wilde C , Leslie K , MacCormick A , Bramley D , Southcott A M , Grant J , Taylor H , Bates S , Towns M , Tippett A , Marshall F , Mazer C D , Kunasingam J , Yagnik A , Crescini C , Yagnik S , McCartney C J L , Choi S , Somascanthan P , Flores K , Wijeysundera D N , Beattie W S , Karkouti K , Clarke H A , Jerath A , McCluskey S A , Wasowicz M , Granton J T , Day L , Pazmino-Canizares J , Oh P , Belliard R , Lee L , Dobson K , Chan V , Brull R , Ami N , Stanbrook M , Hagen K , Campbell D , Short T , Van Der Westhuizen J , Higgie K , Lindsay H , Jang R , Wong C , Mcallister D , Ali M , Kumar J , Waymouth E , Kim C , Dimech J , Lorimer M , Tai J , Miller R , Sara R , Collingwood A , Olliff S , Gabriel S , Houston H , Dalley P , Hurford S , Hunt A , Andrews L , Navarra L , Jason-Smith A , Thompson H , McMillan N , Back G , Croal B L , Lum M , Martin D , James S , Filipe H , Pinto M , Kynaston S , Pearse R M , Abbott T E F , Phull M , Beilstein C , Bodger P , Everingham K , Hu Y , Niebrzegowska E , Corriea C , Creary T , Januszewska M , Ahmad T , Whalley J , Haslop R , McNeil J , Brown A , MacDonald N , Pakats M , Greaves K , Jhanji S , Raobaikady R , Black E , Rooms M , Lawrence H , Koutra M , Pirie K , Gertsman M , Jack S , Celinski M , Levett D , Edwards M , Salmon K , Bolger C , Loughney L , Seaward L , Collins H , Tyrell B , Tantony N , Golder K , Ackland G L , Stephens R C M , Gallego-Paredes L , Reyes A , Gutierrez del Arroyo A , Raj A , Lifford R 
Published: January 2024

ABSTRACT

Background
Post-operative acute kidney injury (PO-AKI) is a common surgical complication consistently associated with subsequent morbidity and mortality. Prior kidney dysfunction is a major risk factor for PO-AKI, however it is unclear whether serum creatinine, the conventional kidney function marker, is optimal in this population. Serum cystatin C is a kidney function marker less affected by body composition and might provide better prognostic information in surgical patients.

Methods
This was a pre-defined, secondary analysis of a multi-centre prospective cohort study of pre-operative functional capacity. Participants were aged ≥40 years, undergoing non-cardiac surgery. We assessed the association of pre-operative estimated glomerular filtration rate (eGFR) calculated using both serum creatinine and serum cystatin C with PO-AKI within 3 days after surgery, defined by KDIGO creatinine changes. The adjusted analysis accounted for established AKI risk factors.

Results
A total of 1347 participants were included (median age 65 years, interquartile range 56–71), of whom 775 (58%) were male. A total of 82/1347 (6%) patients developed PO-AKI. These patients were older, had higher prevalence of cardiovascular disease and related medication, were more likely to have intra-abdominal procedures, had more intraoperative transfusion, and were more likely to be dead at 1 year after surgery 6/82 (7.3%) vs 33/1265 (2.7%) (P = .038). Pre-operative eGFR was lower in AKI than non-AKI patients using both creatinine and cystatin C. When both measurements were considered in a single age- and sex-adjusted model, eGFR-Cysc was strongly associated with PO-AKI, with increasing risk of AKI as eGFR-Cysc decreased below 90, while eGFR-Cr was no longer significantly associated.

Conclusions
Data from over 1000 prospectively recruited surgical patients confirms pre-operative kidney function as major risk factor for PO-AKI. Of the kidney function markers available, compared with creatinine, cystatin C had greater strength of association with PO-AKI and merits further assessment in pre-operative assessment of surgical risk.