Cost analysis of five antimicrobial regimens for the treatment of intra-abdominal infection.

Background: Cost of treatment is an important consideration in antimicrobial agent selection for intra-abdominal infection. We analyzed the relation between the total cost of inpatient stay and the initial selection of antimicrobial agent.

Methods: Actual costs of inpatient care were calculated for 1,234 patients treated at 22 hospitals with one of five antimicrobial regimens: Ampicillin/sulbactam (n = 428), ertapenem (n = 143), ceftriaxone (n = 101), levofloxacin (n = 245), or piperacillin/tazobactam (n = 317) for intra-abdominal infections. Length of stay (LOS), demographic data, diagnosis, disease severity index, intensive care unit (ICU) stay, and total and specific costs were obtained from a large hospital-based, service level, comparative database for five types of infection (appendicitis, cholecystitis, diverticulitis, pancreatitis, and postoperative infection).

Results: The LOS was shorter for appendicitis (3.8 days) and cholecystitis (4.6 days) than for diverticulitis (11.4 days), pancreatitis (8.1 days), or postoperative infection (8.4 days). Length of stay and total cost were most closely related to severity index (p < 0.01) and ICU days (p < 0.01). When patient and hospital characteristics and correlations within hospitals were accounted for in the model, piperacillin/tazobactam was associated with significantly higher cost than ertapenem, ampicillin/sulbactam, and levofloxacin.

Conclusions: In assessing pharmacoeconomic outcomes in the treatment of intra-abdominal infection, cost of treatment, although lower with certain antimicrobial agents, is dependent on severity-of-illness indicators.