Fatigue is a common complaint among adults living with an acquired brain injury(ABI). Perceived fatigue can be persistent, disabling, and limiting for reintegration intoeveryday life. Despite the large impact of fatigue, scientific evidence is limited in guidingclinical practice for treating and assessing fatigue. This thesis comprises two researchprojects concerning rehabilitation of fatigue following ABI. The first project concerns thedevelopment of a treatment model for promoting self-management of fatigue. The secondconcerns the validation of the Danish translation of Dutch Multifactor Fatigue Scale (DMFS).In Denmark, a common approach to treating fatigue in neurorehabilitation includeseducational and behavioral strategies, termed energy management (EM; energiforvaltning).However, the approach is not well defined. Consensus is lacking regarding its components,and underpinning treatment theories are largely unarticulated. Paper I, “Defining aTreatment Model for Self-Management of Fatigue Following Acquired Brain Injury: ACollective Case Study Using the Rehabilitation Treatment Specification System”, presents amodel of EM based on practice-based routines and understandings at a specialized braininjury rehabilitation center. First, an initial model was co-produced with clinicians in iterativeworkshops using the Rehabilitation Treatment Specification System. Next, the model wasrefined in a collective case study of four individuals in vocational rehabilitation. The EMmodel comprises five main treatment components: (a) Knowledge and Understanding ofFatigue, (b) Interoceptive Attention of Fatigue, (c) Acceptance of Fatigue, (d) ActivityManagement, and (e) Self-Management of Fatigue. The model may facilitate theory-drivenevaluation research and guide clinical decision-making in tailored treatment.
Treatment planning implies valid assessment instruments. DMFS addresses themultifaceted nature of fatigue following ABI in order to facilitate targeting of treatment toindividual needs. DMFS comprises 38 items distributed on five subscales: (a) Impact ofxiiFatigue, (b) Signs and Direct Consequences of Fatigue, (c) Mental Fatigue, (d) PhysicalFatigue, and (e) Coping with Fatigue. A multicenter validation study on DMFS wasconducted using both qualitative (Paper II) and quantitative (Paper III) methods. In Paper II,“Evaluation of Response Processes to the Danish Version of the Dutch Multifactor FatigueScale in Stroke Using the Three-Step Test-Interview”, nine adults with stroke wereinterviewed to investigate interpretative processes involved in responding to DMFS. In PaperIII, “Measurement Properties of the Dutch Multifactor Fatigue Scale in Early and LateRehabilitation of Acquired Brain Injury in Denmark”, unidimensionality, measurementinvariance, and factorial structure of the original subscales were evaluated among 149 adultsin rehabilitation of ABI using factor analysis. 
Joint results from both papers support validity of the subscales Impact of Fatigue,Signs and Direct Consequences of Fatigue, and Mental Fatigue. Further, they were partiallyinvariant across early versus late rehabilitation settings. Physical Fatigue demonstratedevidence of local dependency, indicated by both interview and factor analyses. Coping withFatigue was not unidimensional, although response processes were congruent with theintended (multifaceted) construct. Consequently, sumscores are not readily interpreted. Theentire scale was multidimensional, but the original factorial structure was not adequatelyreproduced. Altogether, the three first-named subscales are recommended for measuringfatigue, although constructs may be overlapping. Properties of individual items is analyzed,and item revisions to the Danish translation are recommended.
Several methodological strengths and limitations are considered in the appraisal offindings, including data triangulation, sample size, and generalization. Finally, clinicalimplications and future perspectives for rehabilitation of fatigue following ABI are discussed,including the prospects of using DMFS as a preassessment tool for targeting EM componentsto individual needs.