To evaluate the cost-effectiveness of ertapenem versus piperacillin/tazobactam in the treatment of community-acquired complicated intraabdominal infections accounting for development of antibiotic resistance in the Dutch setting.
A decision tree was developed to estimate cost-effectiveness of ertapenem versus piperacillin/tazobactam at different time points after introduction of treatment. Development of resistance was incorporated using a compartment model. Resistance was a function of the eradication rate of pathogens and antibiotic prescription. Model outcomes included quality-adjusted life years (QALYs), direct costs and cost per QALY saved. Microbiological eradication rate, clinical success, and costs were derived from literature. The analyses included pathogens with intrinsic or acquired resistance.
The model suggested overall savings of €355 (95% uncertainty interval €480; €1205) per patient when abdominal infections are treated with ertapenem instead of piperacillin/tazobactam. Probabilistic sensitivity analysis found a 94% probability of the incremental cost per QALY saved being within the generally accepted threshold for cost-effectiveness (€20,000). After 5 years, it is expected that antibiotic resistance with piperacillin/tazobactam has increased with a greater rate compared to ertapenem, and cost-savings with ertapenem are expected to increase to €672 (€−232; €1617). Ertapenem will, in addition, result in greater success rates and in QALY savings (0.17; 0.07–0.30). Alternative scenarios, with lower levels of initial resistance confirm the cost savings with ertapenem.
Given the underlying assumptions and data used, this evaluation demonstrated that ertapenem is a cost saving and possibly an economically dominant therapy over piperacillin/tazobactam for the treatment of community-acquired intraabdominal infections in The Netherlands.