Reverse Human Factors Engineering

What is “Reverse Human Factors Engineering?”

Clinical Testing seeks to answer the question, “What happens clinically when the device is used perfectly?” while usability testing seeks to answer the question, “What could potentially happen clinically when the device is used imperfectly?” In this way, Clinical Testing and Usability Testing have opposite agendas.

The human factors engineering process is followed to uncover use errors in an effort to improve a medical product’s design and/or to demonstrate use-safety. “Reverse human factors engineering” is the act of intentionally minimizing human variability and eliminating use errors to focus on non-user-related variables such as physiological response by patients.

Sometimes clinical trials fail, and the team is never able to ascertain the true root cause of the failure. Without collecting human factors data during clinical trials, it’s impossible to know whether an outlier event was due to a use error or whether it was due to a truly problematic physiological response.

Reverse Human Factors – The Clinical Study Observation Roadmap

The objective with this type of observation is to eliminate human error as much as possible and to track instances of human variability, for use in creating a data set that promotes meaningful analysis of clinical results.

The method of attaining this objective is to develop a robust Clinical Personnel Training based on the Use FMEA and Usability testing data. The observers must maintain Clinical Personnel Training records. They must also confirm that all personnel interacting with the device have completed training records on file before using the device on a patient. Trained human factors observers must directly observe each procedure and complete an observation checklist for patient/subject. This checklist is based on data in the Use FMEA and clinician/designer input,** and it includes:
  • HCPs involved (names)
  • Patient ID
  • Date/Time
  • Human Factors Observer name
  • Instances of minor deviation from the protocol/training 
  • Instances of significant deviation from the protocol/training
The best strategy is for the Observer to also provide Clinical Personnel Training to build rapport with clinical personnel, and to create a scenario where he/she can interrupt and notify the clinical personnel in the case of a serious use error.

The benefit of Reverse Human Factors Engineering is: Human Factors data that explains unexpected variability in the clinical outcomes and/or supports exclusion of outliers (due to not following the protocol), as applicable. As well as, having the potential to interrupt users and prevent critical use errors that could make or break the study outcome.


Clinical Studies are not intended to examine product usability; as such, human error should be eliminated wherever possible from clinical studies. Robust training, direct supervision, and usability data collection should be employed to control for human error in clinical studies.

**Sometimes a literature review is employed to identify variability in technique associated with the given product. For example, UserWise identified that the following attributes could lead to variability in drug uptake and should be isolated or monitored for during drug delivery device clinical trials: pinching technique, needle depth, device angle, injection location, proximity to navel, fluid flow speed, etc. All of these behaviors could potentially influence the clinical study outcome due to influencing drug uptake.

UserWise, a ClariMed Company | October 25, 2019

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