A PCR-based diagnostic testing strategy to identify carbapenemase-producing Enterobacteriaceae carriers upon admission to UK hospitals: early economic modelling to assess costs and consequences

BACKGROUND: Carbapenemase-producing Enterobacteriaceae (CPE), bacteria which are resistant to the carbapenem class of antibiotics, present an urgent public health risk. The objective of this study was to assess the potential costs and consequences of implementing a testing strategy involving a polymerase chain reaction (PCR)-based diagnostic test for CPE amongst high risk patients upon admission to UK hospitals, to replace the current culture-based testing strategy. METHODS: A decision-analytic model was developed to estimate the expected medical care costs associated with a PCR testing strategy for CPE compared with the current culture testing strategy, and to consider the consequences, in terms of the diagnostic accuracy and associated cost implications, of each approach. The modelled population were patients admitted to hospital at high risk of colonisation with CPE, with model pathways for current practice based on those described in the Public Health England (PHE) toolkit for CPE testing. Costs were estimated from a UK National Health Service (NHS) perspective, with outcomes presented in terms of percentage of samples identified as true positive, false positive, true negative and false negative following each method of testing. RESULTS: Results indicated that the PCR testing strategy led to an estimated cost saving of £462 per patient for a 5-day hospital stay. For all sensitivity analyses conducted, PCR testing resulted in an expected cost saving. Potential cost savings approached £850 per patient for the sensitivity analysis assuming a 15-day hospital stay, indicating that PCR testing results in greater cost savings as length of stay increases. Fewer false positive, and more true negative, cases were identified with the PCR testing strategy in all analyses conducted. CONCLUSIONS: This economic analysis gives an insight into the potential cost savings that could be made by the UK NHS through the introduction of a PCR-based diagnostic testing strategy to replace current recommended culture-based methods for the detection of CPE. Savings are due primarily to a faster time to result with PCR, meaning that CPE-free patients are not isolated unnecessarily. Therefore, a PCR-based diagnostic may aid appropriate use of isolation resource.