Patients who have proteinuria prior to surgery are at elevated risk of postoperative acute kidney injury (AKI) and 30-day unplanned hospital readmission, regardless of preoperative estimated glomerular filtration rate (eGFR), according to investigators.
In a retrospective, population-based study of 153,767 surgeries, a team led by Mary T. Hawn, MD, MPH, of Stanford University in Stanford, California, found that preoperative proteinuria was associated with postoperative AKI in a dose-dependent relationship. Compared with the absence of proteinuria, urine protein concentrations of 15–29 (trace proteinuria), 30–100, 101–300, and 301–1000 mg/dL were associated with 1.2-, 1.3-, 1.7-, and 2-fold greater odds of postoperative AKI, respectively, after adjusting for eGFR and other covariates, the investigators reported in JAMA Surgery.
These proteinuria values were associated with 1.2-, 1.3-, 1.7-, and 1.7-fold increased odds of postoperative AKI, respectively, among patients with a normal eGFR (greater than 60 mL/min/1.73 m2) before surgery, and 1.3-, 1.3-, 1.7-, and 2.2-fold increased odds, respectively, among those with abnormal eGFR before surgery.
Urine protein concentrations of 30–100, 101–300, and 301–1000 mg/dL were associated with 1.1-, 1.1-, and 1.3-fold greater odds of 30-day unplanned readmission.
“Preoperative proteinuria was independently associated with postoperative AKI and 30-day postdischarge, unplanned readmission among patients with and without preoperative renal dysfunction,” the authors concluded. “Preoperative proteinuria is a marker for perioperative AKI risk and readmission in his population. Identification and early intervention with patients at risk for AKI … through preoperative urinalysis assessments may improve patient outcomes by alerting care teams of excess risk despite normal eGFR.”
Wahl TS, Graham LA, Morris MS, et al. Association between preoperative proteinuria and postoperative acute kidney injury and readmission. JAMA Surg. 2018; published online ahead of print.