Pilot study on the psychometric properties of a digital self-administered physical performance test: Evidence from psychosomatic patients
Mia Grote, Nina Schnaderbeck, Felix Fischer, Alizé A. Rogge, Antje Förster, Matthias Ziegler, Matthias Rose, Gregor LieglBackground
Physical function is a central clinical outcome in various medical fields. Performance outcome (PerfO) assessments provide meaningful insights into patients’ physical capabilities, supporting individualized care. However, PerfO assessments are resource-intensive and typically require clinical staff, making them unsuitable for independent home use.
Objectives
This pilot study evaluates the potential of a newly developed digital self-administered version of the 9-item Physical Performance Test (PPT-9), including agreement with its observer-based counterpart among patients with psychosomatic disorders.
Methods
The original PPT-9 is a comprehensive PerfO battery, covering a broad range of standardized physical tasks administered by an external observer. To evaluate initial psychometric properties, N = 39 patients completed the PPT-9 twice: first in the self-administered version using tablet computers, with patient-facing instructions developed through expert evaluation and subsequently in the original version, assessed by clinical staff. Internal consistency and inter-method agreement were assessed using Cronbach’s alpha and Intraclass Correlation Coefficient (ICC); agreement between self-administered and observer-based PPT-9 scores was analyzed using the standardized mean difference (SMD), Bland-Altman plots, and paired
Results
The self-administered version showed good internal consistency (Cronbach’s α=0.88) and was highly correlated with the observer-based version (Pearson correlation=0.92), with slightly longer completion times possibly related to self-timing within the app interface.
Conclusion
These findings support the feasibility of transforming an established performance outcome measure into a digital self-assessment tool. Although adjustments might be required to account for systematic scoring differences, the digital PPT-9 could improve access to functional assessment in underserved settings by reducing personnel and clinic-based infrastructure requirements.