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Sunday, 15 October 2006


Matt Stevenson, PhD, The School of Health and Related Research, University of Sheffield., Sheffield, England, Jeremy E. Oakley, PhD, University of Sheffield, Sheffield, England, Stephen E. Chick, PhD, INSEAD, Fontainebleau, France, and Kalipso Chalkidou, National Institute for Health and Clinical Excellence, London, England.

Purpose. To estimate the cost-effectiveness of introducing single-use instruments to stop iatrogenic vCJD compared with maintaining re-usable instruments.

Methods. A discrete event simulation model was constructed to simulate the potential number of iatrogenic vCJD infections caused by contaminated surgical instruments that are not sufficiently cleaned by decontamination procedures. The modelling horizon was set to 5 years, due to an expectation that an intervention would be available that successfully decontaminated instruments at this time. The model was populated with data from the literature and from elicitation sessions with experts, as epidemiological parameters and the effectiveness of decontamination procedures held great uncertainty. All patients incubating vCJD at the start of the model were assumed to contaminate surgical instruments if they underwent surgery. The clinical outcome of patients that were infected during surgery depended upon genotype. Clinical symptoms developed in 100%, 50% and 20% of M/M, M/V and V/V patients, respectively. Those infected and assumed not to develop clinical symptoms were assumed carriers. All patients infected would contaminate instruments on future surgery once the infectious period was reached. Analyses were performed incrementally, initially determining that the introduction of single-use instruments was not cost-effective for sites excluding the brain and the posterior eye. Further analyses were undertaken assuming that instruments migrating between sets continued at the estimated present level, and assuming that this could be successfully prohibited. Additional analyses assessed the introduction of single-use instruments targeted at people who had previously undergone surgery.

Results Assuming instrument migration could be successfully prohibited, the cost per QALY of targeting single-use instruments in the brain and posterior eye were £99k and £45k, respectively. These values decreased to £19k and £4k if instrument migration continued due to the increase in the expected number of iatrogenic infections. Introducing single-use instruments for all patients had an incremental cost per QALY of £47k and £16k, respectively compared with the targeted approach.

Conclusions. The cost-effectiveness of policies introducing single-use instruments is dependent on the level of instrument migration. Any intervention that could ensure this was prohibited was cost-effective. Assuming a MAICER of £30k per QALY, single-use sets were not cost-effective when instrument migration was prohibited. If migration could not be prohibited single-use instruments for all posterior eye operations and targeted single-use for brain operations are cost-effective policies.

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See more of The 28th Annual Meeting of the Society for Medical Decision Making (October 15-18, 2006)