Horton et al. (2026)
- Authors: M. Horton, Sarah F. Tyson, Russell Fleming, S. Gladwell
- Institutes: University of Manchester, Manchester, UK, The ME Association, Buckingham, UK
- Publisher: medRxiv (Preprint)
- Link: DOI
Summary
The development of TIMES provides a scientifically validated tool specifically designed to measure the wide-ranging and fluctuating symptoms of ME/CFS. By moving beyond simple clinical checklists to a psychometrically sound scale, this study enables more precise tracking of the disease’s impact on patients’ daily lives. It offers clinicians and researchers a reliable way to assess symptom severity and frequency, which is essential for improving individual care and the quality of data in clinical trials.
What was researched?
This study describes the creation and validation of The Index of Myalgic Encephalomyelitis Symptoms (TIMES), a new tool designed to measure the symptom burden of ME/CFS. Researchers tested the instrument’s internal structure and content validity to ensure it accurately and reliably reflects the patient experience.
Why was it researched?
Existing symptom assessments for ME/CFS often lack formal psychometric validation and may not fully capture the disease’s multi-system complexity. The researchers aimed to develop a stable, clinically relevant tool through direct partnership with patients and clinicians to fill this gap.
How was it researched?
The team identified 85 symptom items across eight domains through literature reviews and focus groups with patients and clinicians. An initial online survey of 721 people with ME/CFS was analyzed using Rasch modeling to refine the items and response formats. A revised version was then validated in a second cohort of 354 participants to confirm the scale’s stability and measurement accuracy.
What has been found?
The analysis determined that a four-point response format for symptom frequency and severity was more effective than the original five-point scale. The final TIMES instrument satisfied all Rasch model requirements, confirming that its domain scales are unidimensional and stable. Specific sub-scales for neurological and autonomic symptoms were also validated, providing a robust framework for assessing the diverse symptoms of the condition.
Discussion
A major strength of the study is its co-production approach, ensuring that the tool is relevant to both clinicians and the patient community. While the current validation was conducted with a primarily UK-based cohort, the rigorous statistical analysis suggests the tool is highly reliable. This paper focuses on construct and content validity, while a companion study addresses further reliability metrics.
Conclusion & Future Work
The TIMES tool is a stable and valid assessment of ME/CFS symptoms suitable for both research and clinical use. It is freely available and provides a much-needed standardized measure for tracking patient symptoms over time.