Validation of the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) in patients with inflammatory bowel disease

Background Many patients with ulcerative colitis (UC) and Crohn's disease (CD) complain of significant fatigue. To date, no instrument to measure fatigue has been validated in a US inflammatory bowel disease (IBD) population. Aim To determine the reliability and validity of the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) scale in IBD. Methods A total of 209 patients with IBD completed the 13 items of the FACIT-F, alongside laboratory testing and disease activity assessment. Internal consistency was measured by Cronbach's alpha; test-retest reliability by the intraclass correlation coefficient (ICC); validity by the correlation of the FACIT-F score with C-reactive protein (CRP) erythrocyte sedimentation rate (ESR), haematocrit (HCT) and disease activity as measured by the Harvey-Bradshaw Index (HBI; CD) and Simple Clinical Colitis Activity Index (SCCAI; UC). Results The mean ± SD FACIT-F score was 38.9 ± 11.0 overall (CD 38.6 ± 11.3; UC 39.4 ± 10.6). Cronbach's alpha was 0.94. The ICC for first and repeat FACIT-F scores assessed within 180 days without change in disease state was 0.81 (CD 0.78; UC 0.87). FACIT-F scores were lower in patients with active symptoms (CD 4.6 points, 95% CI 2.4-6.9, P < 0.001; UC 8.5 points, 95% CI 5.5-11.4, P < 0.001). In UC, FACIT-F scores were correlated with ESR (-0.76, 95% CI -0.89 to -0.50), CRP (-0.72, 95% CI -0.88 to -0.43) and HCT (0.53, 95% CI 0.22-0.74). Conclusion The FACIT-F scale is a reliable and valid instrument for measuring fatigue in IBD.