Development and psychometric testing of inflammatory bowel disease fatigue (IBD-F) patient self-assessment scale

Fatigue is one of the main symptoms of inflammatory bowel disease (IBD) and is frequently reported by people in both active and quiescent disease. Many different fatigue assessment scales have been used to measure fatigue, but none has been developed or tested in IBD. This study aimed to develop a fatigue scale specific to the needs and experiences of people with IBD.

A five-step sequential mixed method design was used: a qualitative phase to assess patients' experience of fatigue and its impact on their lives, and four mixed qualitative-quantitative phases to refine the scale and to assess its psychometric properties.

567 people participated in five phases. The resulting questionnaire has 3 sections: 5 questions assessing frequency and severity of fatigue; 30 questions rating the experience and impact of fatigue; and a free-text section asking for patients' comments and additional issues related to fatigue. Initial validation suggests that the questionnaire has good face and content validity, acceptable to excellent test-retest stability (ICC 0.74 for Section 1 and 0.83 for Section 2) and a high degree of internal consistency (Cronbach's alpha>0.9).

Participants in the study confirmed that fatigue in IBD is burdensome. Items generated and refined by people with IBD-fatigue reflect their experience and form the basis of this new IBD-fatigue scale, which is psychometrically robust with reliability estimates which fall within statistically acceptable ranges. The scale can be used by patients and practitioners to assess severity and impact of fatigue in people with IBD.