Comparative cost effectiveness of gentamicin and tobramycin.

Gentamicin and tobramycin were compared for cost effectiveness in the treatment of adult patients with serious infections in a general medical service. We used data from a randomized double-blind trial in which the only observed difference between the clinical effects of these aminoglycosides was the incidence of nephrotoxicity (26% with gentamicin and 12% with tobramycin). According to 1984 cost data, the combined average drug and nephrotoxicity costs per patient were $127 for tobramycin and $72 for gentamicin. An extensive sensitivity analysis--varying frequency and cost of nephrotoxicity, dialysis requirements, aminoglycoside acquisition costs, and length of hospitalization--showed gentamicin to be more cost effective than tobramycin, unless hospitalization is prolonged by an average of at least 15 days for patients with severe nephrotoxicity or at least 3 days for all patients with moderate or severe nephrotoxicity.