The FSI-Interference Scale was used to determine symptom
(fatigue) distress. The distress dimension within the theory of
unpleasant symptoms refers to the degree to which a person
is bothered by the symptom and the symptom interferes with
activities of daily living. The FSI has several items, which
corresponded to the timing of fatigue (time of day, number
of days per week fatigue occurs, and pattern of fatigue). The
Short Form-36 (McHorney, Ware, & Raczek, 1993), a measure
of HRQoL, was used as a reflection of performance. Qualitative
interviews were completed to obtain a comprehensive
description of fatigue and add descriptive depth to each of
the dimensions within the theory of unpleasant symptoms