An extended protocol for usability validation of medical devices

Display Omitted A longitudinal extension to common validation protocols for medical devices is proposed.Normative path deviations are used as a measure for fallibility in user-device interaction.A reference regression model for longitudinal validation testing is developed and provided as a statistical program.The extensions are demonstrated in a comparative validation study on syringe infusion pumps. This paper proposes and demonstrates an extended protocol for usability validation testing of medical devices. A review of currently used methods for the usability evaluation of medical devices revealed two main shortcomings. Firstly, the lack of methods to closely trace the interaction sequences and derive performance measures. Secondly, a prevailing focus on cross-sectional validation studies, ignoring the issues of learnability and training. The U.S. Federal Drug and Food Administrations recent proposal for a validation testing protocol for medical devices is then extended to address these shortcomings: (1) a novel process measure normative path deviations is introduced that is useful for both quantitative and qualitative usability studies and (2) a longitudinal, completely within-subject study design is presented that assesses learnability, training effects and allows analysis of diversity of users. A reference regression model is introduced to analyze data from this and similar studies, drawing upon generalized linear mixed-effects models and a Bayesian estimation approach. The extended protocol is implemented and demonstrated in a study comparing a novel syringe infusion pump prototype to an existing design with a sample of 25 healthcare professionals. Strong performance differences between designs were observed with a variety of usability measures, as well as varying training-on-the-job effects. We discuss our findings with regard to validation testing guidelines, reflect on the extensions and discuss the perspectives they add to the validation process.