What is a Human Factors (or Usability) Study?

Human factors (or usability) studies (HFS) are designed to evaluate the “user interface” of a device, or of a drug-device combination product. The user interface refers to all points of interaction between the user and the device, including the totality of package, labeling and/or software instructions, the physical device itself, and other elements that may be for training, physical controls or visual displays (see FDA guidance here). The goal of an HFS is to demonstrate that the device can be used by intended users under expected conditions in a way that eliminates or mitigates potential use-related hazards. Elements of the user interface that are not amenable to direct performance may be evaluated through knowledge-based assessments (KBA). Additionally, in the case of a device intended for nonprescription use, the FDA often views “self-selection,” meaning the ability of unsupervised consumers to correctly recognize if they are “intended users” or not, as a critical HFS task. Iterative stages of HF testing include:

1. Formative Human Factors Tests: These preliminary studies are often conducted in a small number of participants to inform user interface design during development to reveal important use issues and identify critical tasks. The results aid in refining the interface and study methods in preparation for validation testing.
2. Summative or Validation Studies: These formal studies are conducted among representative users and evaluate all critical tasks related to the interface under conditions that simulate realistic use. Samples generally consist of 15 or more participants per distinct user group. Performance is evaluated task-by-task, with each one ultimately classified as successful, a “close call” (user difficulty but with action taken to prevent harm from occurring), or a use error, with careful evaluation of underlying root causes. Results may inform further refinements to the user interface and are ultimately designed to support submission to the FDA or other regulatory authority.

HFS to test software user interfaces for technology mediated “ACNU” products involve a unique set of procedures and design considerations. See our “Additional Conditions for Nonprescription Use” page for more information.

PEGUS scientific consultants are highly adept at interpreting FDA requests, helping sponsors optimize device labeling and other elements of the user interface, and designing and executing HFS research. If you have questions about how PEGUS can assist with human factors research for your device or combination product, please click here or call us at 801-990-6126.