A PROMIS fatigue short form for use by individuals who have multiple sclerosis

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-Fatigue_MS.

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-Fatigue_MS that maximized relevance rankings, content coverage, and item discrimination. The PROMIS-Fatigue_MS and an existing, 7-item PROMIS fatigue short form (PROMIS-Fatigue_SFv1.0) were administered to a new sample of 231 individuals with MS. Known groups and content validity were assessed.

Scores from the short forms were highly correlated (r = 0.92). Discriminant validity of the PROMIS-Fatigue_MS scores was supported in known groups comparisons. Scores of neither short form exhibited an advantage in quantitative analyses.
The PROMIS-Fatigue_MS targeted more of the content included in participants’ responses to open-ended questions than did the PROMIS-Fatigue_SFv1.0.

The PROMIS-Fatigue_MS was derived to have content validity in MS samples. The validity of the measure was further supported by the ability of PROMIS-Fatigue_MS items to discriminate among groups expected to differ in levels of fatigue. We recommend its use in measuring the fatigue
of individuals with MS.