Preoperative Proteinuria Predicts Adverse Renal Outcomes after CABG
A study published in the Journal of the American Society of Nephrology looked at proteinuria by dipstick prior to OHS to see if it would predict post-op AKI or renal replacement therapy (RRT).
The investigators performed a secondary analysis of a prospectively enrolled cohort of adult patients undergoing coronary artery bypass grafting (CABG) at a medical center and its two affiliate hospitals between 2003 and 2007. This excluded patients with stage 5 CKD or those who received dialysis previously. They defined proteinuria, measured with a dipstick, as mild (trace to 1+) or heavy (2+ to 4+). Among a total of 1052 patients, cardiac surgery–associated acute kidney injury (CSA-AKI) developed in 183 (17.4%) patients and required renal replacement therapy (RRT) in 50 (4.8%) patients. In a multiple logistic regression model, mild and heavy proteinuria each associated with an increased odds of CSA-AKI, independent of CKD stage and the presence of diabetes mellitus (mild: OR 1.66, 95% CI 1.09 to 2.52; heavy: OR 2.30, 95% CI 1.35 to 3.90). Heavy proteinuria also associated with increased odds of postoperative RRT (OR 7.29, 95% CI 3.00 to 17.73).
Although this is one study fraught with issues, this data suggest that preoperative proteinuria is a strong predictor of CSA-AKI among patients undergoing CABG. More studies are needed, but this is not a surprising finding. It is simple, quick and cheap to measure proteinuria and IMHO it should be checked routinely on patients pre-op to risk stratify prior to OHS.