An Economic Model to Assess the Cost Impact of Using Xpert Carba-R to Screen Carbapenemase-Producing Enterobacterales in Comparison with Standard of Care, in a National Health Service Setting.

Introduction: Carbapenemase-producing Enterobacterales (CPE) are bacteria that produce carbapenemases, enzymes that destroy carbapenem antibiotics and result in carbapenem resistance. Early identification of individuals who have been colonised or infected is important to correctly implement infection prevention and control procedures. Chromogenic media culture is traditionally the most common method of screening for high-risk patients. However, there is a long wait for results, which has substantial cost and operational implications. Xpert Carba-R is a rapid molecular test that provides CPE screening results in 50 min. This study aimed to assess the cost impact of high-risk CPE screening with Xpert Carba-R compared with media culture.

Methods: An economic model was developed using a probabilistic cost-comparison approach to estimate the costs associated with Xpert Carba-R, from a National Health Service and personal social services perspective. The model cohort was individuals at high risk of CPE colonisation and used an 8.30-day mean time horizon for all patients to cover hospitalisation time, with an extra 5.80 days added for patients that were truly colonised to cover the time they would spend in isolation (14.10-day time horizon overall). Deterministic sensitivity analysis and scenario analysis were used to determine the robustness of the findings.

Results: The model found that Xpert Carba-R is cost saving compared with media culture, with incremental cost savings of £818.28 per person. Despite greater technology costs, there are cost savings associated with preventing unnecessary isolation.

Conclusion: The analysis found Xpert Carba-R to be cost saving compared with media culture for CPE screening in high-risk patients. The model did not explore onwards transmission or the opportunity cost of releasing isolation spaces, so the cost savings are likely to be far greater than those demonstrated in this study.