Purpose
To derive from the Patient Reported Outcomes Measurement Information System (PROMIS) fatigue item bank, a short form for individuals with multiple sclerosis (MS), the PROMIS-FatigueMS.
Methods
A panel of 37 clinicians and 46 individuals with MS ranked the relevance of PROMIS fatigue items to persons with MS. Eight items were selected for the PROMIS-FatigueMS that maximized relevance rankings, content coverage, and item discrimination. The PROMIS-FatigueMS and an existing, 7-item PROMIS fatigue short form (PROMIS-FatigueSFv1.0) were administered to a new sample of 231 individuals with MS. Known groups and content validity were assessed.
Results
Scores from the short forms were highly correlated (r = 0.92). Discriminant validity of the PROMIS-FatigueMS scores was supported in known groups comparisons. Scores of neither short form exhibited an advantage in quantitative analyses. The PROMIS-FatigueMS targeted more of the content included in participants’ responses to open-ended questions than did the PROMIS-FatigueSFv1.0.
Conclusions
The PROMIS-FatigueMS was derived to have content validity in MS samples. The validity of the measure was further supported by the ability of PROMIS-FatigueMS items to discriminate among groups expected to differ in levels of fatigue. We recommend its use in measuring the fatigue of individuals with MS.