Risk Factors for Low Vancomycin Trough Level in Adult General Ward Inpatients: a Retrospective Cohort Study

Several studies have described factors such as augmented renal clearance that lead to low trough levels of vancomycin (VCM) in patients in the intensive care unit (ICU). In contrast, few studies have examined such factors in patients admitted to general wards. Therefore, the purpose of this study was to clarify factors associated with low VCM trough levels in general ward inpatients. We conducted this retrospective study on patients who had been monitored for changes in VCM blood levels at Gunma University Hospital for a 5-year period from January 1, 2014. Children under 18 years of age, pregnant women, and patients receiving renal replacement therapy were excluded; in total, 217 patients were examined. Subjects were divided into two groups: a low-level group comprising 88 patients with an initial trough concentration of less than 10 g/mL and an optimal group comprising 129 patients with a trough concentration of 10 -20 g/mL. Of the 177 general ward patients other than ICU, 74 were in the low-level group and 103 were in the optimal group. Multivariate logistic regression analysis revealed that low uid volume, febrile neutropenia (FN), and non-sepsis were mainly independent risk factors for reduced trough levels. We believe that FN is one of the important risk factors for low trough levels, especially in general ward patients rather than ICU.