Are you concerned about your fatigue? Fatigue perceptions mediate the relationship between insomnia and fatigue related functional impairment in chronic hepatitis C infection

Abstract

Insomnia affects about one third of patients with chronic hepatitis C infection. Fatigue is the cardinal daytime symptom of insomnia. Those with comorbid insomnia are the most fatigued patients at liver clinics. Although we have successful treatments for insomnia, fatigue is a frequent residual complaint. This is especially concerning since chronic fatigue is associated with significant functional impairment in this group. Understanding the psychological mechanisms that maintain fatigue and fatigue related functional impairment in those with a history of co-morbid insomnia may facilitate the development of CBT-I treatments enhanced with a fatigue treatment component in the medically ill. Treatment seeking participants with chronic hepatitis C infection ( N = 115; 36% females; mean age = 56) were enrolled in a mixed design study on fatigue. Participants completed questionnaires on their fatigue, sleep, fatigue specific cognitions, depression and anxiety. Medical data were retrieved from hospital charts. Fatigue was assessed with the Fatigue Severity Scale (FSS), insomnia was assessed with the Insomnia Severity Index (ISI). The Brief Illness Perception Questionnaire, the Chronic Fatigue Acceptance Questionnaire and the Daytime Insomnia Symptom Response Scale were used for measuring fatigue specific cognitive factors. A bootstrapping mediation analysis (confidence level: 5000 resamples) revealed that the effect of insomnia on fatigue was fully mediated by two domains of fatigue perception: concern about fatigue (standardized effect = .3759, bias corrected accelerated confidence interval = .2444 to .5127) and control over fatigue (standardized effect = .0891, bias corrected accelerated confidence interval = .0290 to .1968). Patients’ concern about their fatigue and their perceived degree of control over their fatigue provided the link between insomnia (ISI) and fatigue related functional impairment (FSS). Future research should test this theoretical model in other medically ill populations with comorbid insomnia and significant fatigue. The model implies that a fatigue-focused component targeting fatigue perceptions and fatigue management may become an important addition to the insomnia treatment in the medically ill.