Association of Preoperative Urinary Uromodulin with AKI after Cardiac Surgery

Background and objectives AKI is a serious complication after cardiac surgery. Although high urinary concentrations of the tubular protein uromodulin, a marker of tubular health, are associated with less AM in animal models, its relationship in humans is unknown. Design, setting, participants, & measurements A post hoc analysis of a prospective cohort study of 218 adults undergoing on pump cardiac surgery between 2004 and 2011 was conducted. Multivariable logistic and linear regression analyses were used to evaluate the associations of preoperative urinary uromodulin-to-creatinine ratio with postoperative AM (defined as a rise in serum creatinine of >0.3 mg/dl or >1.5 times baseline); severe AM (doubling of creatinine or need for dialysis) and peak postoperative serum creatinine over the first 72 hours. Results Mean age was 68 years, 27% were women, 95% were white, and the median uromodulin-to-creatinine ratio was 10.0 mu g/g. AM developed in 64 (29%) patients. Lower urinary uromodulin-to-creatinine ratio was associated with higher odds for AM (odds ratio, 1.49 per 1-SD lower uromodulin; 95% confidence interval, 1.04 to 2.13), which was marginally attenuated after multivariable adjustment (odds ratio, 1.43; 95% confidence interval, 0.99 to 2.07). The lowest uromodulin-to-creatinine ratio quartile was also associated with higher odds for AKI relative to the highest quartile (odds ratio, 2.94; 95% confidence interval, 1.19 to 7.26), which was slightly attenuated after multivariable adjustment (odds ratio, 2.43; 95% confidence interval, 0.91 to 6.48). A uromodulinto-creatinine ratio below the median was associated with higher adjusted odds for severe AM, although this did not reach statistical significance (odds ratio, 4.03; 95% confidence interval, 0.87 to 18.70). Each 1-SD lower uromodulin-to-creatinine ratio was associated with a higher adjusted mean peak serum creatinine (0.07 mg/dl per SD; 95% confidence interval, 0.02 to 0.13). Conclusions Lower uromodulin-to-creatinine ratio is associated with higher odds of AKI and higher peak serum creatinine after cardiac surgery. Additional studies are needed to confirm these preliminary results.