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How many testers are needed to assure the usability of medical devices?

Borsci, Simone; Macredie, Robert D.; Martin, Jennifer L.; Young, Terry

Authors

Simone Borsci

Robert D. Macredie

Jennifer L. Martin Jennifer.martin@nottingham.ac.uk

Terry Young



Abstract

Before releasing a product, manufacturers have to follow a regulatory framework and meet standards, producing reliable evidence that the device presents low levels of risk in use. There is, though, a gap between the needs of the manufacturers to conduct usability testing while managing their costs, and the requirements of authorities for representative evaluation data. A key issue here is the number of users that should complete this evaluation to provide confidence in a product's safety. This paper reviews the US FDA's indication that a sample composed of 15 participants per major group (or a minimum of 25 users) should be enough to identify 90-97% of the usability problems and argues that a more nuanced approach to determining sample size (which would also fit well with the FDA's own concerns) would be beneficial. The paper will show that there is no a priori cohort size that can guarantee a reliable assessment, a point stressed by the FDA in the appendices to its guidance, but that manufacturers can terminate the assessment when appropriate by using a specific approach - illustrated in this paper through a case study - called the 'Grounded Procedure'.

Citation

Borsci, S., Macredie, R. D., Martin, J. L., & Young, T. (2014). How many testers are needed to assure the usability of medical devices?. Expert Review of Medical Devices, 11(5), doi:10.1586/17434440.2014.940312

Journal Article Type Article
Publication Date Sep 1, 2014
Deposit Date Jul 30, 2015
Publicly Available Date Jul 30, 2015
Journal Expert Review of Medical Devices
Print ISSN 1743-4440
Electronic ISSN 1743-4440
Publisher Taylor & Francis
Peer Reviewed Peer Reviewed
Volume 11
Issue 5
DOI https://doi.org/10.1586/17434440.2014.940312
Keywords Evaluation cohort, Five-user assumption, Medical devices, product safety, Usability testing
Public URL http://eprints.nottingham.ac.uk/id/eprint/29451
Publisher URL http://informahealthcare.com/doi/abs/10.1586/17434440.2014.940312
Copyright Statement Copyright information regarding this work can be found at the following address: http://eprints.nottingh.../end_user_agreement.pdf

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf





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