Wahl TS, et al. - Among patients with and without known renal dysfunction at the time of surgery, the researchers examined the relationship between preoperative proteinuria and postoperative acute kidney injury (AKI) and 30-day unplanned readmission. It was found that proteinuria was correlated with postoperative AKI and 30-day unplanned readmission independent of preoperative estimated glomerular filtration rate (eGFR). Findings suggested that simple urine assessment for proteinuria might identify subjects at higher risk of AKI and readmission to guide perioperative management.

Methods

• It was a retrospective, population-based study.
• From October 1, 2007, to September 30, 2014, this investigation was conducted in a cohort of patients with and without known preoperative renal dysfunction undergoing elective inpatient surgery performed at 119 Veterans Affairs facilities.
• From April 4 to December 1, 2016, data analysis was conducted.
• Eligibility criteria included preoperative dialysis, septic, cardiac, ophthalmology, transplantation, and urologic cases.
• Preoperative proteinuria as evaluated by urinalysis using the closest value within 6 months of surgery: negative (0 mg/dL), trace (15-29 mg/dL), 1+ (30-100 mg/dL), 2+ (101-300 mg/dL), 3+ (301-1000 mg/dL), and 4+ (>1000 mg/dL).
• Postoperative predischarge AKI and 30-day postdischarge unplanned readmission was the primary outcome.
• Any 30-day postoperative outcome was the included secondary outcomes.

Results

• According to the findings obtained, out of 346,676 surgeries, 153,767 met inclusion criteria, with the majority involving orthopedic (37%), general (29%), and vascular procedures (14%).
• Findings revealed that evidence of proteinuria was appeared in 43.8% of the population (trace: 20.6%, 1+: 16.0%, 2+: 5.5%, 3+: 1.6%) with 20.4%, 14.9%, 4.3%, and 0.9%, respectively, of the patients having a normal preoperative eGFR.
• Preoperative proteinuria was significantly correlated with postoperative AKI (negative: 8.6%, trace: 12%, 1+: 14.5%, 2+: 21.2%, 3+: 27.6%; P < .001) and readmission (9.3%, 11.3%, 13.3%, 15.8%, 17.5%, respectively, P < .001) in unadjusted analysis.
• Preoperative proteinuria was correlated with postoperative AKI in a dose-dependent relationship (trace: odds ratio [OR], 1.2; 95% CI, 1.1-1.3, to 3+: OR, 2.0; 95% CI, 1.8-2.2) and 30-day unplanned readmission (trace: OR, 1.0; 95% CI, 1.0-1.1, to 3+: OR, 1.3; 95% CI, 1.1-1.4) after adjustment.
• Data reported that preoperative proteinuria was linked with AKI independent of eGFR.