Elevated Vancomycin Trough Levels in a Tertiary Health System: Frequency, Risk Factors, and Prognosis

To investigate the frequency of, risk factors for, and outcomes after elevated levels of vancomycin.

We identified hospitalizations among 21,285 individuals in which intravenous vancomycin was given between August 29, 2007, and October 10, 2014. We investigated frequency and risk factors for elevated vancomycin levels (trough levels >30 mg/L) as well as associations with subsequent acute kidney injury (AKI), length of stay, and in-hospital mortality.

Among the 21,285 patients, the mean age was 62.9 years, and 10,478 (49.2%) were female. Trough levels of vancomycin were checked in 7422 patients, and 755 elevated levels were detected. Compared with patients with trough levels checked but no elevated levels found, those with elevated levels had longer duration of vancomycin therapy (median, 6.0 days vs 3.4 days; P<.001) and slightly higher doses (mean, 1.72 g vs 1.58 g; P<.001). Patients with higher body mass index or lower estimated glomerular filtration rate had more elevated levels. In propensity-matched analyses, patients had higher risk of incident AKI after elevated levels compared with patients without elevated levels (hazard ratio, 1.55; 95% CI, 1.09-2.20; P=.02), as well as longer subsequent length of stay (relative risk, 1.14; 95% CI, 1.02-1.28; P=.03) but similar in-hospital mortality.

In this study, elevated vancomycin levels were common, particularly in patients with higher body mass index and lower estimated glomerular filtration rate, and were associated with greater subsequent AKI and length of stay.