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Retrospective Hypomimia Rating via Mobile App: A Usability Study.
Alexander Johannes Wiederhold1, Lea Haidar1, Christopher Gundler1
1Institute for Applied Medical Informatics, University Medical Center Hamburg-Eppendorf.
Studies in Health Technology and Informatics
|May 23, 2026
Summary
This study shows the CAPtion app offers excellent usability for rating hypomimia, or reduced facial expressiveness, in Parkinson's disease patients. The tool supports standardized scoring, improving consistency among raters.
Area of Science:
- Neurology
- Medical Technology
Background:
- Hypomimia, characterized by reduced facial expressiveness, is a common yet challenging symptom in Parkinson's disease (PD) to assess consistently.
- Objective and standardized rating of hypomimia is crucial for clinical trials and patient management.
Purpose of the Study:
- To evaluate the usability of CAPtion, an iOS application designed for standardized, session-based retrospective rating of hypomimia.
- To determine the suitability of CAPtion for enabling structured scoring of hypomimia across multiple independent raters.
Main Methods:
- Six Parkinson's disease specialists used the CAPtion application for a predefined hypomimia rating session.
- Participants completed the System Usability Scale (SUS) post-session to assess usability.
Main Results:
- The CAPtion application achieved a high mean SUS score of 91.7 (±6.8).
- This score indicates excellent usability and user satisfaction with the application.
Conclusions:
- The CAPtion application demonstrates excellent usability for hypomimia assessment in Parkinson's disease.
- The app is suitable for scaling to larger studies requiring inter-rater reliability assessments for hypomimia.

