Evidence-based medicine, health costs and intra-abdominal infection treatment
Anti-infectious drugs are among the most-prescribed medications in the community, in 1997 being more than 9% of all drugs prescribed by the Spanish National Health System. In the particular case of the treatment of patients with moderate or severe intra-abdominal infection, economic aspects are important. Antimicrobial therapy is responsible for as much as 50% of the drug budget in some Spanish hospitals. On the other hand, as more options become available for the treatment of intra-abdominal infection, it is important to know their clinical and economic consequences. Imipenem/cilastatin (IC) is a broad-spectrum beta-lactam antibiotic that has demonstrated its effectiveness in the treatment of nosocomial and community-acquired bacterial infections. The objective of this study was to determine if IC has a favorable cost-effectiveness relation compared to other antibiotic therapies for the treatment of intra-abdominal infections. A cost-effectiveness analysis was made based on retrospective information on the treatment of patients over 18 with clinical suspicion of moderate-to-severe intra-abdominal infection. Health-care results were measured in natural health units (percentage of clinically favorable cases) in a systematic review of the literature. Direct health-care costs associated with the treatments compared were calculated. The other options studied, apart from IC, included the most common and least expensive option (a combination of an aminoglycoside and an anaerobicide [AA]) and an antibiotic from the same family as IC, meropenem (M). The results, in terms of the percentage of patients with clinically favorable results, showed that the effectiveness of IC was equivalent to that of M (95.2% vs. 96.4%) and the AA association (88.0% vs. 86.6%). Analysis of cost minimization showed that the total cost per patient treated with the IC and M options was similar, but that the lower price of IC slightly reduced the total cost per patient treated (ptas. 455,320 IC and ptas. 483,404 M). In the comparison of IC and AA, the higher price of IC was compensated for by the lower cost associated with the duration of hospitalization in patients treated with IC (total cost per patients treated ptas. 844,678 IC and ptas. 1,009,180 AA). The results of the meta-analysis showed that imipenem/cilastatin was highly effective (more than 90% clinically favorable results) and that it can be considered a minimum equivalent to meropenem and to the combination of an aminoglycoside and anaerobicide for the treatment of patients with moderate or severe intra-abdominal infection. Given the equivalence in effectiveness of the options studied, analysis of cost minimization was used to study their relative effectiveness. This analysis showed that IC was accompanied by lower costs per patient than M and AA. The most relevant variables in the study of the efficiency of the treatment of intra-abdominal infections were, in conditions of equivalent effectiveness, days of hospitalization (and associated costs) and drug price.