OBJECTIVE:To evaluate validity, reliability, and targeting of the Norwegian 7-item Fatigue Severity Scale (FSS-7) in adults with moderate-to-severe traumatic brain injury (TBI). SETTING:Inpatient and outpatient acute care and postacute rehabilitation facilities. PARTICIPANTS:Ninety-four patients with intracranial injury, 20% women, with a mean age of 45.8 years (SD = 13.6), provided 185 complete FSS-7 responses at 6 months (n = 94) and 12 months (n = 91) post-TBI. DESIGN:Secondary analysis of data from a longitudinal observational study using the Rasch model and graphical log-linear Rasch models (GLLRM). MAIN MEASURES:The FSS-7 is a self-report fatigue measure derived from the original FSS by omitting items 1 and 2. Differential item functioning (DIF) was examined for sex, age, education, and sleep disturbances (Epworth sleepiness scale and insomnia severity index). RESULTS:The FSS-7 did not fit the Rasch model due to poor fit of item 4 and local dependence between items 5 and 6. A 6-item version (FSS-6), excluding item 4, provided good fit to a GLLRM accounting for the local dependence between items 5 and 6. No DIF or item parameter drift over time was detected. The FSS-6 demonstrated excellent reliability (r = 0.936), while targeting was less than optimal, as on average, only 57% of the maximum obtainable test information was reached. CONCLUSIONS:The FSS-6, excluding item 4, provides a valid measure of fatigue with excellent reliability for adults at 6 and 12 months post-TBI. The total raw score is invariant across sex, age, educational level, and sleep disturbances with no item parameter drift from 6 to 12 months postinjury. The FSS-6 may be useful for screening and monitoring fatigue in TBI rehabilitation and research, although a reassessment of targeting is recommended for future research on a larger and broader sample of patients.

Traumatic brain injury (TBI) causes major societal burden and may negatively influence an individual’s health-related quality of life (HRQoL). Personality factors have been linked to persistent post-concussion symptoms (PPCS), and PPCS have been found to affect HRQoL. However, there is a knowledge gap concerning the association between personality traits and HRQoL after mild-to-moderate TBI. Thus, this study aims to investigate the association between personality traits and HRQoL in patients with mild-to-moderate TBI at 15 months post-injury, while controlling for socio-demographic characteristics, injury-related factors and symptom burden. Data from 86 participants with mild- to-moderate TBI from a previous randomised controlled trial were analysed. Sociodemographic, injury-related and psychological factors were recorded 2–3 months post-injury. Personality traits were measured at 15 months post-injury with The NEO Five-factor Inventory-3. The Quality of Life after Brain Injury– Overall Scale (QOLIBRI-OS) and the EuroQol-visual analogue scale (EQ-VAS) were used to measure HRQoL at 15 months post-injury. Two separate multiple linear regression models were performed for the outcome variables; QOLIBRI-OS (model 1) and EQ-VAS (model 2). The factors associated with lower HRQoL were more severe PPCS, higher levels of the personality traits neuroticism and conscientiousness (model 1), female sex and being single/living alone (model 2). Higher levels of the personality trait extraversion were associated with higher HRQoL in both models. The results highlight how non-injury factors may be associated with recovery and HRQoL after TBI. Considering personality factors may be helpful when identifying individual risk and protective factors for outcomes after mild-to-moderate TBI.

Objective:To explore factors associated with stability and change in fatigue from 6 to 12 months following traumatic brain injury (TBI). Setting:Combined in- and outpatient acute care and postacute rehabilitation settings. Participants:A total of 103 patients with confirmed intracranial injury were assessed 6 and/or 12 months following TBI. Design:A prospective observational study with repeated measures at 2 time points, analyzed with a hybrid mixed-effects model. Main Measures:Primary outcomes were the fatigue factor derived from items from several fatigue patient-reported outcome measures (PROMs; Fatigue Severity Scale, Chalder Fatigue Scale, Giessen Subjective Complaints List-fatigue subscale, and Rivermead Post-Concussion Symptoms Questionnaire-fatigue item) Secondary outcomes were PROMs relating to pain, somatic and psychological distress, insomnia, sleepiness, personality traits, optimism, resilience, behavioral activation and inhibition, and loneliness, as well as neuropsychological measures. Demographic variables and injury severity characteristics were included as covariates. Results:In multilevel regression, female sex, years of education, and 3 factors related to injury severity, somatic vulnerability, and psychosocial robustness were all significantly associated with variation in fatigue between subjects, and explained 61% of the variance in fatigue that was due to stable between-subject differences. Fatigue levels declined significantly over time. Changes in pain severity, somatic symptom burden, psychological distress, and behavioral inhibition were positively associated with changes in fatigue, explaining 22% of the variance in fatigue within subjects. Conclusions:The study demonstrated that several previously implicated factors show robust effects in distinguishing individuals with TBI on levels of fatigue, but only a few show additional within-subject associations across time. Pain severity, somatic symptom burden, psychological distress, and behavioral inhibition correlated with fatigue across time, implicating these factors as crucial targets for rehabilitation of patients with TBI who suffer from persistent fatigue.

Approximately 30% of individuals with mild traumatic brain injury (mTBI) experience persistent post-concussion symptoms (PPCS). Personality factors have been linked to PPCS, yet, the association between personality traits and outcomes after mTBI is poorly understood. The aim of this study was to evaluate the association between personality traits, PPCS, and return to work (RTW) in patients with mild-to-moderate traumatic brain injury (TBI). Data from eighty-seven participants with mild-to-moderate TBI were analyzed. Sociodemographic, injury, and work characteristics and depressive symptoms were recorded 2–3 months post-injury. Personality traits were measured using the NEO Five-Factor Inventory-3. PPCS and RTW were assessed 15 months post-injury. Multiple linear regression models were performed. The factors associated with more severe PPCS were female sex, higher levels of neuroticism, openness to experience and conscientiousness, extra-cranial injuries, and depressive symptoms. The factors associated with lower RTW were female sex, higher levels of neuroticism, and conscientiousness. However, after controlling for PPCS, personality traits were no longer significantly associated with RTW. In conclusion, specific personality traits were associated with more severe PPCS and may be indirectly associated with RTW via PPCS. Hence, personality traits may be important to assess to identify patients at risk of less favorable outcomes after mild-to-moderate TBI.

Objective Fatigue is a common symptom in somatic and mental illness. Musculoskeletal pain and psychological distress have in turn frequently been shown to be associated with fatigue across clinical conditions and in the general population. The study aims to disentangle direct effects from those due to mere confounding from shared etiologies. Design The study used genetically informative longitudinal twin data, through a co-twin control design with an additional within-person dimension. Methods Data on fatigue, pain and distress from 2196 mono - and dizygotic twins from the Norwegian Twin Registry examined at two time points five years apart was analyzed using multilevel generalized linear regression modeling. Fatigue was regressed on pain and distress, with further controls added for confounding from genetic and stable non-shared environmental sources. Results Pain and distress had a significant impact on fatigue at genetic, stable non-shared environmental and time-varying levels, even when controlling for somatic comorbidity. Conclusion The findings indicate that a significant proportion of the association between fatigue, pain and distress is due to genetic and environmental confounding. Pain and distress exert significant, albeit smaller effects on fatigue even when controlling for genetic and stable environmental contributions, indicating direct effects. Potential etiological pathways and underlying mechanisms are discussed.

Fatigue is a common symptom after traumatic brain injuries (TBI) and a crucial target of rehabilitation. The subjective and multifactorial nature of fatigue necessitates a biopsychosocial approach in understanding the mechanisms involved in its development. The aim of this study is to provide a comprehensive exploration of factors relevant to identification and rehabilitation of fatigue following TBI. Ninety-six patients with TBI and confirmed intracranial injuries were assessed on average 200 days post-injury with regard to injury-related factors, several patient-reported outcome measures (PROMS) of fatigue, neuropsychological measures, and PROMS of implicated biopsychosocial mechanisms. Factor analytic approaches yielded three underlying factors, termed Psychosocial Robustness, Somatic Vulnerability and Injury Severity. All three dimensions were significantly associated with fatigue in multiple regression analyses and explained 44.2% of variance in fatigue. Post hoc analyses examined univariate contributions of the associations between the factors and fatigue to illuminate the relative contributions of each biopsychosocial variable. Implications for clinical practice and future research are discussed.