Fatigue measurements in systemic lupus erythematosus

Objective. Fatigue is a frequent, disabling issue in systemic lupus erythematosus (SLE). It is, however, difficult to quantify. The Ad Hoc Committee on SLE Response Criteria for Fatigue in 2007 recommended using the Krupp Fatigue Severity Scale (FSS). Since then, the Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue Scale has also been validated in SLE. We performed a review of instruments used to measure fatigue in adult SLE patients from 2007 onward. Methods. We searched PubMed, Medline, and Embase (January 2008-October 2017), identifying clinical trials and observational studies in adult SLE, where fatigue was a specifically measured outcome. All English and French studies were reviewed to determine fatigue measures and results. Results. Thirty-seven studies met inclusion criteria. Eight scales were used. The visual analog scale (VAS), FSS, and FACIT-Fatigue Scale were most frequent. FSS was the most often used instrument in both clinical trials and observational studies. Twenty-five of the 37 studies demonstrated a difference in fatigue that was statistically significant and clinically meaningful. Of the 12 studies that did not, 6 used FSS, 3 used VAS, 2 used the Multidimensional Assessment of Fatigue, and 1 used the Brief Fatigue Index. All 6 studies using the FACIT-Fatigue Scale detected clinically meaningful and statistically significant differences. Conclusion. VAS, FSS, and FACIT-Fatigue Scale were the most frequently used instruments in adult SLE studies from 2008 to 2017. Many studies detected clinically important changes in fatigue. Fatigue remains a key measure in both clinical trials and observational SLE studies.