Incidence and risk factors of vancomycin-associated acute kidney injury in a single center: Retrospective study

Background: There is enough evidence to suggest that vancomycin increases the risk of acute kidney injury (AKI) but the exact mechanism is not well understood. This study aims to understand the incidence of vancomycin-associated acute kidney injury (VA-AKI) among hospitalized patients and to identify the risk factors for VA-AKI. Methods: Patients aged 18 and above who received a minimum of 24 hours of intravenous vancomycin and who had serial creatinine measurements over a 13-month period were identified through electronic records. Patients with pre-existing AKI, or eGFR of less than 30ml/min, and patients with end stage kidney disease were excluded. Results were analyzed using t-test and Fisher’s test. A logistic regression model was used to identify the predictors for VA-AKI. Results: From the 598 patients who met the inclusion criteria, 70 developed AKI. Compared to those without AKI, patients with VA-AKI had higher mean serum vancomycin trough levels (22.6 mg/L vs. 14.6 mg/L), and a statistically significant longer duration of vancomycin use (6.7 vs. 5.2 days). Multivariate analysis revealed that serum vancomycin level of > 20 mg/L was associated with a six-fold increase in odds of VA-AKI when compared to those with vancomycin levels < 15 mg/L. The presence of hypotension, iodinated contrast use, and concomitant use of piperacillin-tazobactam were all associated with increased odds of VA-AKI. Conclusion: The incidence of VA-AKI in hospitalized patients with eGFR > 30 ml/min was 11.7%. Serum vancomycin levels of > 20 mg/L, hypotension and administration of iodinated contrast significantly increased the risk of VA-AKI. Piperacillin-tazobactam, when used with vancomycin, was noted to be an independent predictor of AKI, regardless of serum vancomycin trough levels, prompting a reevaluation of the safety of this widespread practice as empiric therapy. Close monitoring of kidney function, avoiding high serum vancomycin levels, maintaining hemodynamic stability, and avoiding unnecessary use of iodinated contrast seem to be essential for the prevention of VA-AKI