Navigating Vancomycin and Acute Kidney Injury: AUC- vs. Trough-Guided Monitoring in Initial and Steady-State Therapy

<b>Background/Objectives</b>: Vancomycin, a glycopeptide antibiotic used for gram-positive infections, is associated with acute kidney injury (AKI). Therapeutic drug monitoring (TDM) is recommended to minimize this risk while ensuring therapeutic efficacy. This study evaluated whether AUC-guided monitoring improved patient safety compared to traditional trough-guided monitoring. <b>Methods</b>: A retrospective observational cohort study was conducted at the University Medical Centre Maribor, Slovenia, involving patients receiving intravenous vancomycin. One cohort was managed using trough-guided monitoring (<i>n</i> = 85), while the other was monitored using the AUC-guided approach (<i>n</i> = 139). The primary outcome was AKI incidence, and secondary outcomes included renal replacement therapy and mortality. Risk factors for AKI were identified, and pharmacokinetic parameters were evaluated at vancomycin therapy initiation and steady state. <b>Results</b>: The incidence of AKI was 20% in the trough-guided group and 18% in the AUC-guided group (<i>p</i> = 0.727). Secondary outcomes were similar in both cohorts. Risk factors for AKI included older age (OR 1.04; <i>p</i> = 0.042), higher steady-state AUC (OR 1.01; <i>p</i> < 0.001), longer duration of concomitant nephrotoxic therapy (OR 1.06; <i>p</i> = 0.019), and concomitant use of loop diuretics (OR 2.46; <i>p</i> = 0.045). Steady-state AUC values and trough levels (AUC_0-24ss, AUC_24-48ss, AUC_0-48ss, and C_min48ss) were significantly lower in the AUC-guided group, which was further reflected in the lower percentage of patients exceeding the AUC > 600 mg·h/L threshold at steady state. <b>Conclusions</b>: Although AKI incidence was lower in the AUC-guided group, the difference did not reach statistical significance. However, lower AUC values and trough levels in the AUC-guided group at steady state suggest a trend toward reduced vancomycin exposure and toxicity.