Cost comparison of two antimicrobial regimens for treating mixed aerobic-anaerobic infections.

The costs of cefoxitin sodium therapy and clindamycin phosphate plus amikacin sulfate therapy for mixed aerobic-anaerobic infections were compared. A randomized, prospective study was undertaken with 70 adult patients with documented or suspected serious aerobic-anaerobic infections. It had been shown that the two therapies did not differ in efficacy or incidence of toxicity. The cost to the pharmacy for one day's therapy was chosen as the unit of cost comparison. Cost-per-day data were calculated by the unit-price and price-allocation methods with and without a sterile-products charge. Amikacin was added to the cefoxitin regimen when resistant organisms were cultured. To extend the analysis to other aminoglycosides, rough comparisons were made for "equivalent" doses of tobramycin sulfate and gentamicin sulfate. Fifty-four patients completed the trial (77%). The cost of cefoxitin therapy was significantly less than that of clindamycin plus amikacin therapy and cefoxitin plus amikacin therapy (p less than 0.001) by both pricing methods. When gentamicin and tobramycin were substituted for amikacin sulfate, the cost per day for therapy, according to the price-allocation method, was still significantly less for cefoxitin (p less than 0.001). Cost analysis is an important component in the selection of the appropriate therapy after the efficacy and toxicity of therapeutic regimens have been shown to be equivalent.