Psychometric evaluation of the PROMIS<sup>®</sup> physical function short form 12a for use by adults with myalgic encephalomyelitis/chronic fatigue syndrome. — CFSMEATLAS
Psychometric evaluation of the PROMIS® physical function short form 12a for use by adults with myalgic encephalomyelitis/chronic fatigue syndrome.
Yang, Manshu, Keller, San, Rafiee, Parisa et al. · Health and quality of life outcomes · 2025 · DOI
Quick Summary
Researchers tested whether a questionnaire called PROMIS Physical Function Short Form (PF-SF) works well for measuring how much ME/CFS affects a person's ability to do physical activities. They asked 173 people with ME/CFS and 161 healthy people to complete the questionnaire and found that it accurately captured the differences in physical ability between the two groups. The questionnaire appears to be a reliable and useful tool for doctors and researchers to measure physical function in people with ME/CFS.
Why It Matters
Measuring physical function accurately is essential for understanding ME/CFS disease severity, tracking patient progress, and evaluating treatments. This study provides evidence that the PROMIS PF-SF is a reliable tool for clinical practice and research, which could standardize how doctors assess and compare physical disability across ME/CFS patients.
Observed Findings
People with ME/CFS scored an average of 40.5 on the PROMIS PF-SF, about one standard deviation below the national average of 50.
The questionnaire showed no meaningful floor or ceiling effects, meaning it can distinguish between different levels of impairment.
People with ME/CFS had substantially worse physical function scores than healthy controls, with a large effect size (η²=0.70).
Physical function scores increased in a consistent pattern across ME/CFS participants with low, medium, and high functional impairment.
The questionnaire correlated well with other measures of physical function (correlations of 0.47-0.55), supporting its validity.
Inferred Conclusions
The PROMIS PF-SF 12a is a reliable and valid tool for assessing physical function in adults with ME/CFS.
The instrument effectively discriminates between different levels of functional impairment in ME/CFS and between ME/CFS and healthy populations.
The PROMIS PF-SF can be confidently used in both clinical practice and research settings to measure physical function outcomes in ME/CFS.
Remaining Questions
Can the PROMIS PF-SF detect meaningful changes in physical function over time in ME/CFS patients (test-retest reliability and responsiveness)?
What This Study Does Not Prove
This study does not prove that the PROMIS PF-SF can detect changes in physical function over time (longitudinal validity) or predict future outcomes. It also does not establish whether this questionnaire is superior to other existing measures of physical function, only that it works adequately for ME/CFS populations. The study is observational and does not address causation or mechanisms underlying the physical impairments measured.