Jim Kling

May 03, 2013

BERLIN, Germany — The current methicillin-resistant Staphylococcus aureus (MRSA) screening policy in place at the National Health Service (NHS) in the United Kingdom is not cost effective, new research suggests.

The NHS recently switched from a policy of screening only high-risk patients to one of routinely screening most patients admitted to the hospital.

After that policy change in December 2010, the NHS commissioned a review of the practice. Researchers used an economic model that incorporated representative national data to determine the effectiveness of widespread screening.

The findings from the review suggest the NHS would be better off reverting to the old policy, Sheldon Stone, MD, from the University College London Medical School in the United Kingdom, told Medscape Medical News.

He presented the results here at the 23rd European Congress of Clinical Microbiology and Infectious Diseases.

Before the policy change, an assessment "concluded that it would be worth doing, but it used historical data from the literature rather than real clinical data or data from all over the country. The feeling in the profession was that there was no way this was going to be cost effective," Dr. Stone explained.

The researchers used data from the literature and a national audit of MRSA screening conducted in May 2011 at 144 acute hospitals. The model they used distinguished high-risk from low-risk specialties, and took into account realistic patient movement patterns among specialties and between the hospital and community. It also considered different hospital models, mortality estimates, costs, and other factors.

There's no evidence that universal screening...is cost effective.

The model compared 6 potential MRSA screening and intervention strategies: no screening; routine screening with or without pre-emptive isolation of previously known MRSA; screening high-risk specialties; and 2 checklist activated screening policies.

Chromogenic agar was used for screenings. Interventions included isolation and decolonization when possible, or decolonization and contact precautions when isolation was not possible. The researchers evaluated the incremental costs and health benefits (measured as quality-adjusted life years [QALYs]) of different MRSA prevalence rates, transmission potentials, and NHS hospital type. They also conducted probabilistic sensitivity analyses that incorporated uncertainty in model parameters.

Overall, the model established that the current policy is not cost effective at the current willingness-to-pay threshold set by the NHS (£30,000/QALY).

When the model restricted screening to high-risk specialties, the hypothetical program was cost effective (£9,964/QALY for acute hospitals, £10,777/QALY for specialist hospitals, and £31,077/QALY for teaching hospitals). This strategy would not prevent transmission to the greatest extent possible, but it would prevent most infections and deaths, according to the researchers.

The conclusions were similar regardless of prevalence, transmission potential, or mortality assumptions, and the certainty level between different strategies was never more than 30%. Reverting to a high-risk screening policy could save the NHS approximately £250 million per year; however, it would lead to an increase of 2 infections per hospital per year and 1 colonization per week per hospital.

"The previous policy of screening high-risk admissions — orthopedic operations, neurosurgery patients, vascular surgery patients — where the majority of long-lasting hard-to-treat fatal infections are, is much more cost effective than any other strategy," Dr. Stone reported.

The NHS would save about £1.5 million per hospital if it reverted to the old policy of screening only high-risk patients. "You could invest £50,000 of that in a psychologist to improve everybody's hand hygiene using behavioral techniques. That would more than counteract your rise in infections," Dr. Stone noted.

The model used can be adapted to other countries, according to Sarah Deeny, PhD, a mathematical modeler at the Health Protection Agency in London, who was one of the researchers. "We have a model that assumes you don't have any transmission of MRSA in the community, but that might not be true in every country," she explained.

"It can be adapted to any healthcare setting if you get your parameters right. It's not just for MRSA; you could stick any bug in there," added Dr. Stone.

"I have always questioned why the NHS came to the decision [to conduct routine screening]. There's no evidence that universal screening for the whole hospital population is cost effective," meeting delegate Marc Bonten, MD, head of the Department of Medical Microbiology at University Medical Center Utrecht, the Netherlands, told Medscape Medical News.

Dr. Bonten said he agrees that hospitals should focus on high-risk patients, but noted that it is not always easy to determine just how many MRSA infections must be caught to minimize MRSA spread. "If you miss 5%, how dangerous is that for your hospital system? If your baseline level of hygiene is high, the likelihood that this 5% will cause problems is low, but if there is no hygiene at all, then that risk is higher," Dr. Bonten said.

High-risk populations also change over time, he added. "You need to update your risk-stratification strategy based on changing epidemiology."

Dr. Stone, Dr. Deeny, and Dr. Bonten have disclosed no relevant financial relationships.

23rd European Congress of Clinical Microbiology and Infectious Diseases (ECCMID): Abstract LB 2969. Presented April 28, 2013.

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