Measuring fatigue in sarcoidosis: the Fatigue Assessment Scale (FAS)

Fatigue is a major problem in a wide range of diseases including sarcoidosis. However, there is no standard measure for assessing fatigue. Therefore, the aim of the present study was to evaluate the usefulness of the Fatigue Assessment Scale (FAS) in two samples of sarcoidosis patients. Sample 1 included 1 046 members of the Dutch Sarcoidosis Society and Sample 2 consisted of 80 sarcoidosis patients of the outpatient clinic of the Sarcoidosis Management Centre Maastricht, the Netherlands. All patients completed the FAS as well as the 'energy and fatigue' subscale of the WHOQOL-100. Additionally, the participants of Sample 1 filled in the Beck Depression Inventory (BDI). In addition, 241 patients of Sample 1 completed the FAS for the second time after a one-week interval. The FAS appeared to be a unidimensional scale. The content validity, construct validity and internal consistency of the FAS were good. The test - retest reliability was.89. Four FAS items appeared to have a gender bias: three items were uniformly biased and one item non-uniformly biased. Correction for gender bias in the calculation of the FAS total score is not indicated. In conclusion, the FAS is a promising measure for assessing fatigue in sarcoidosis patients.