Genomic surveillance of methicillin-resistant Staphylococcus aureus: a mathematical early modelling study of cost effectiveness

Genomic surveillance of MRSA identifies unsuspected transmission events and outbreaks. Used proactively, this could direct early and highly targeted infection control interventions to prevent ongoing spread. Here, we evaluate the cost effectiveness of this intervention in a model that compared whole genome sequencing plus current practice versus current practice alone. A UK cost-effectiveness study was conducted using an early model built from the perspective of the National Health Service (NHS) and personal social services. Effectiveness of sequencing was based on the relative reduction in total MRSA acquisitions in a cohort of hospitalised patients in the year following their index admissions. Sensitivity analysis was used to illustrate and assess the level of confidence associated with the conclusions of our economic evaluation. A cohort of 65,000 patients were ran through the model. Assuming that sequencing would result in a 90% reduction in MRSA acquisition, 290 new MRSA cases were avoided. This gave an absolute reduction of 28.8% and avoidance of two MRSA-related deaths. Base case results indicated that the use of routine, proactive MRSA sequencing would be associated with estimated cost savings of over £728,290 per annual hospitalised cohort. The impact in total QALYs was relatively modest, with sequencing leading to an additional 14.28 QALYs gained. Results were most sensitive to changes in the probability of an MRSA negative patient acquiring MRSA during their hospital admission. We showed that proactive genomic surveillance of MRSA is likely to be cost-effective. Further evaluation is required in the context of a prospective study.