Although the Society for Healthcare Epidemiology of America has recommended active MRSA surveillance, to our knowledge this recommendation has not yet been supported by detailed cost-effectiveness studies.23,24
In fact, there have been calls for economic analyses to determine the value of MRSA surveillance.22,25
Although some studies have outlined the total costs associated with implementing MRSA surveillance in particular units and facilities, they did not include formal economic analyses that looked at whether the effectiveness of these interventions justified the costs.26,27
Moreover, results from one location are not necessarily generalizable to other locations and situations, where MRSA prevalence and incidence can vary geographically and temporally by a significant amount.28
Additionally, the transmission dynamics of MRSA have not been well characterized. It remains unclear how many new MRSA cases an index case will create. Some epidemiological studies have shown that surveillance decreases the incidence of nosocomial infections, whereas others have shown no effect.4,29,30
Our goal was not to make the decision about whether to implement universal surveillance but to provide information about the potential cost-effectiveness of surveillance for different ranges of prevalence and different basic reproductive rates. Such information may help physicians, infection control specialists, hospital administrators, and policy makers make decisions on the basis of their unique local situations and conditions. Our model suggested that universal surveillance may be cost-effective (and in many cases cost-dominant) at a very wide range of prevalence and basic reproductive rate values (a basic reproductive rate from 0.25 to 3.0 and a prevalence of 1% or greater).
By design, our model may have underestimated the benefits of surveillance. We endeavored to be conservative in our cost estimates, choosing the more expensive form of isolation (ie, respiratory-droplet precautions) and the less expensive potential procedures for each MRSA clinical condition. Moreover, aside from mortality, our model assumed no potential chronic disability from MRSA infection (eg, amputation because of severe soft-tissue infection or decreased exercise tolerance because of severe respiratory infection or cardiac surgery). We also did not consider possible benefits to the initially colonized patient, such as decolonization of MRSA-positive patients. Decolonization involves treating the MRSA-colonized patient with antibiotics or disinfectants to remove colonization. However, to date, studies have not clearly established the efficacy of decolonization, because many de-colonized patients reacquire MRSA. Finally, surveillance may confer additional long-term benefits not represented by our model. Information from surveillance (eg, MRSA colonization prevalence and MRSA infection incidence) can help public health personnel, hospital administrators, and researchers track the spread of MRSA and the effectiveness of various system-wide interventions.
Every computer model is a simplification of real life and cannot fully represent every single event and outcome that may occur when an MRSA-colonized patient enters the hospital. The model assumed that patients would be tested and that results would become available before the patient could transmit MRSA to others. Although clinical outcomes may be worse with patients who have significant comorbidities, we did not stratify patients into sociodemographic, clinical, or risk factor groups. Furthermore, our study assumed that no decolonization of MRSA-colonized patients would occur.
Conclusions and Future Directions
Universal MRSA surveillance of adult general medical patients at admission may be cost-effective for a wide range of MRSA prevalences and MRSA transmission dynamics. Individual hospitals and healthcare systems could compare their prevailing conditions with the benchmarks in our model to help determine their optimal local strategies. Future studies should explore how the combinations of prevalence and transmission dynamics may vary from hospital to hospital and how additional measures, such as decolonization, may alter the economic value of surveillance.