To the Editor—We read with interest the cost-benefit analysis by McKinnell et alReference McKinnell, Bartsch, Lee, Huang and Miller ¹ who found that universal screening for methicillin-resistant Staphylococcus aureus (MRSA) may be relative costly for hospitals. We assessed the potential economic aspects of screening as part of a review of national MRSA control guidelines in Ireland. ² We found that MRSA screening is generally advocated as part of infection prevention and control measures, but an important consideration is the cost-effectiveness of the type of screening approach.

For patients admitted to acute hospitals setting, 7 studies (United States, 4; Germany, 1; United Kingdom, 1; Ireland, 1) compared the cost of universal screening with targeted screening of at-risk patients. Costs were limited to direct medical costs and were evaluated from the perspective of the healthcare provider or hospital. Four studies were cost comparisons,Reference Olchanski, Mathews, Fusfield and Jarvis ^{3 –} Reference Kang, Mandsager, Biddle and Weber ⁶ 2 reported cost-effectiveness of the strategies compared with a base case of no screening and relative to each other,Reference Tubbicke, Hubner and Flessa ^{4 ,} Reference Kang, Mandsager, Biddle and Weber ⁶ while 1 study provided a cost-benefit analysis of universal versus targeted screening.Reference Leonhardt, Yakusheva and Costello ⁷ In hospitals where MRSA is endemic, screening (targeted or universal) reduced infection rates and was cost saving compared with a policy of no screening.Reference Olchanski, Mathews, Fusfield and Jarvis ^{3 ,} Reference Tubbicke, Hubner and Flessa ⁴ Universal MRSA screening strategies were more effective but also more cost-intensive than targeted screening.Reference Tubbicke, Hubner and Flessa ^{4 ,} Reference Kang, Mandsager, Biddle and Weber ^{6 ,} Reference Leonhardt, Yakusheva and Costello ⁷

In a retrospective review of a 3-year MRSA screening program that was implemented from 2006 to 2009 in the United Kingdom, only 7 extra MRSA cases were detected using universal screening compared with targeted screening, and in 1 month, universal screening generated 4,200 negative screens that incurred an additional €25,488 in laboratory costs.Reference Collins, Raza, Ford and Gould ⁵ Similarly, a prospective study by Creamer et alReference Creamer, Galvin and Humphreys ⁸ found that extending screening to patients without risk factors (ie, universal screening) increased the number of screenings and the costs but did not result in the detection of a significant number of additional cases. In a 2011 US study, targeted screening was associated with lower costs and better outcomes than a policy of no screening, whereas universal screening was associated with an average cost-effectiveness ratio of €11,769 per MRSA infection.Reference Kang, Mandsager, Biddle and Weber ⁶ In a second cost-effectiveness analysis, targeted screening strategies were found to be more cost-effective than universal screening, with incremental cost-effectiveness ratios of €3,227 to €28,507, depending on the prevalence rate and testing used, compared with €103,169 to €183,269 per additional infection averted for universal screening.Reference Tubbicke, Hubner and Flessa ⁴ Finally, a US prospective study comparing the clinical effectiveness and cost benefit of universal versus targeted screening reported a benefit-to-cost ratio of 0.50, indicating that for every additional euro spent on universal versus targeted screening, only €0.40 could be recovered in avoided costs due to a reduction in MRSA healthcare-associated infection.Reference Leonhardt, Yakusheva and Costello ⁷

The control of MRSA is a multidisciplinary task involving surveillance, patient screening, decolonization, isolation and/or the cohorting of patients, environmental decontamination, antimicrobial stewardship, maintenance of adequate staffing levels, and hand hygiene. Although considerable coordination efforts may need to be invested in control, we demonstrate that the evidence strongly suggests that overall MRSA prevention and control strategies are associated with significant cost savings. The control measures have additional merits because they increase the awareness of the importance of all healthcare-associated infections and their implementation decreases other healthcare-associated infections.Reference Rubinovitch and Pittet ⁹ However, MRSA control measures encompass a wide range of interventions, the efficacy and cost of some of which are dependent on prevalence rates, local resistance patterns, the characteristics of the patient population, and the hospital facilities, all of which will vary from country to country. Because the MRSA prevalence rate in Ireland is higher than in the United Kingdom and in other Northern European countries, MRSA prevention and control is very relevant in the potential efficient use of resources.

In conclusion, the evidence shows that screening, whether universal or targeted, is better than no screening, resulting in fewer MRSA infections. Although universal screening, as currently practiced in the United Kingdom, is the most costly but the most effective strategy, it is not as cost-effective as it is resource intensive. Universal screening detects few additional cases and results in a large number of additional negative screens. However, any evaluation of the effectiveness of screening methods should take account of healthcare costs, methods, the rapidity of test results, and the prevalence of colonization and infection.