Positive impact of a therapeutic drug-monitoring program on total aminoglycoside dose and cost of hospitalization

A prospective evaluation was undertaken to assess the impact of an aminoglycoside therapeutic drug-monitoring (TDM) program on the total dose of aminoglycoside antibiotics, the duration of therapy, the number of serum concentrations determined, the length of hospital stay, and the potential cost reduction in 221 patients with proven or suspected gram-negative infections. The patients were allocated to a group that received individualized aminoglycoside doses (study) or to a group that did not (control). The mean total dose of gentamicin or tobramycin per patient course of therapy was 1,258 mg in the study group and 1,981 mg in the control group (p less than 0.0001). The mean duration of therapy was 5.9 and 10.3 days per patient in the study and control group, respectively (p less than 0.0001). The mean length of hospital stay was 8.4 days in the study group and 11.8 days for the control (p less than 0.005). The type and site of infection, number of serum concentration determinations, and mortality were not statistically different for the groups. These data indicate that a TDM program can markedly reduce the total dose of aminoglycoside, which can potentially reduce tissue accumulation and toxicity. In addition, the hospital costs were $725 less per patient in the study group, which would produce a savings of approximately $640,000 per year at our institution.