AMSTERDAM—Pre-operative American Society of Anesthesiology (ASA) scores independently predict the onset of post-operative acute kidney injury (AKI) in surgical patients, U.K. researchers reported at the 51st Congress of the European Renal Association–European Dialysis and Transplant Association.  

Michael Bedford, MBBS, Renal Research Registrar at East Kent University Hospitals NHS Foundation in Canterbury, and colleagues tested the ability of ASA score to predict AKI following surgery using data from general anesthetic operative procedures conducted with pre- and post-operative renal function testing. The procedures were performed over a recent 2-year period at three U.K. hospitals.

Although traditional risk factors such as age, diabetes, heart disease are important in gauging AKI risk, the investigators had believed that co-morbidity may not fully reflect functional status.

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Developed more than 50 years ago, the ASA score provides a subjective assessment of a patient’s overall health that is based on a 5-category physical status classification system and is used to stratify patients prior to surgery.

In the study by Dr. Bedford’s group, AKI developed post-operatively in 5.8%, 9.2%, 15.1%, 22.0%, 45.4% of patients with an ASA score of 1, 2, 3, 4, and 5, respectively.

ASA score was independently associated with the development of AKI post-operatively.  Compared with a patient who had an ASA score of 1, those with an ASA score of 3, 4, and 5 were at 1.5, 2.0, and 3.7 times increased risk of post-operative AKI.

“This study demonstrates that ASA status pre-operatively is an important predictor of developing AKI post-operatively in an unselected general hospital population,” the researchers concluded in their study abstract. “This raises the possibility of using ASA to stratify risk and direct interventions pre-operatively to ultimately prevent AKI.”

Dr. Bedford’s group also noted that their results “show the superiority of functional status over the presence of co-morbidity in risk stratification.”