Content Validation of the Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue Scale in Moderately to Highly Active Rheumatoid Arthritis

Abstract

Objective: Fatigue is one of the most burdensome symptoms of Rheumatoid Arthritis (RA), thus validated measures are needed to assess it in practice and research. Although performance and responsiveness of the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) has been demonstrated in moderately to highly active RA and several other conditions, the face and content validity of the instrument in this context has not been evaluated. Methods: Semi-structured interviews were conducted with patients with moderately to highly active RA. Participant comments were analysed using a constant comparative approach, and findings were mapped to the FACIT-Fatigue to assess content validity. Results: A total of 17 patients participated in the study; saturation was obtained after 16 interviews. Participants had been living with an RA diagnosis from 2 months to 36 years. Participants were primarily female (82%), white (59%), and mean age was 54. FACIT-Fatigue was found to have good face validity and strong content validity for RA. No significant gaps in content were identified. However, three items were found to be less relevant to RA fatigue: “I feel weak all over”, “I feel listless (‘washed out’)”, and “I am too tired to eat”. + Conclusion: The FACIT-Fatigue has good face and content validity for patients with moderately to highly active RA. The instrument could be further tailored to RA patients by removing a few items deemed less relevant than others in this context; however, even those less-relevant items retained their relevance for a good number of patients.