Vancomycin Trough and Acute Kidney Injury: A Large Retrospective, Cohort Study

<b><i>Background:</i></b> The association between vancomycin trough (VT) and acute kidney injury (AKI) at the recommended doses remains controversial. <b><i>Methods:</i></b> The authors conducted a retrospective, observational cohort study of 500 adult patients who received vancomycin for ≥72 h. Data collected included 2 main predictors: average VT (including only VTs before the occurrence of AKI), first VT and other possible risk factors for AKI. The baseline characteristics/variables between patients with AKI and patients with no AKI were compared. Logistic regression models were used to develop multivariate models. The authors divided the patients into 4 subgroups: (1) VT <10, (2) 10 ≤ VT < 15, (3) 15 ≤ VT < 20 and (4) VT ≥20 µg/ml. All subgroups were compared to subgroup 2 (reference group). <b><i>Results:</i></b> AKI occurred in 12.85% of patients while on vancomycin. The incidence of AKI in subgroups 1-4 was 8.02, 13.61, 13.70 and 31.82%, respectively, using the first VT, that is significantly higher in subgroup 4. Using average VT, AKI incidence was 5, 10.38, 19.01 and 25.58%, respectively, that is significantly higher in subgroups 3 and 4. On multivariate logistic regression, average VT, first VT, average VT >15, first VT >15, methicillin-resistant <i>Staphylococcus aureus</i> infection and morbid obesity were significantly associated with increased incidence of AKI. <b><i>Conclusion:</i></b> Clinicians should be careful when aiming for a VT >15 μg/ml as this is associated with increased incidence of AKI.