The multiple mediating effects of vision-specific factors and depression on the association between visual impairment severity and fatigue: a path analysis study

• Published in: BMC psychiatry Vol. 24; no. 1; pp. 572 - 12
• Main Authors: Schakel, Wouter, Bode, Christina, van de Ven, Peter M, van der Aa, Hilde P A, Hulshof, Carel T J, van Rens, Gerardus H M B, van Nispen, Ruth M A
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 21.08.2024; BioMed Central; BMC
• Subjects: Activities of Daily Living; Adult; Aged; Analysis; Arthritis; Blindness; Care and treatment; Chronic fatigue syndrome; Chronic illnesses; Cognition; Comorbidity; Cross-Sectional Studies; Depression; Depression - complications; Depression, Mental; Development and progression; Diagnosis; Eye; Fatigue; Fatigue - complications; Fatigue - physiopathology; Female; Humans; Low vision; Male; Mediation; Medical research; Medicine, Experimental; Mental depression; Middle Aged; Netherlands; Older people; Patients; Population studies; Prevention; Questionnaires; Risk factors; Severity of Illness Index; Sociodemographics; Structural equation modeling; Variables; Vision; Vision Disorders - complications; Vision Disorders - physiopathology; Vision Disorders - psychology; Vision, Low - complications; Vision, Low - physiopathology; Vision, Low - psychology; Vision-specific quality of life; Visual acuity; Visual impairment; Work capacity; Netherlands; Depression; Fatigue; Low vision; Vision-specific quality of life; Structural equation modeling; Visual impairment
• ISSN: 1471-244X; 1471-244X
• DOI: 10.1186/s12888-024-06014-5

Severe fatigue is a common symptom for people with visual impairment, with a detrimental effect on emotional functioning, cognition, work capacity and activities of daily living. A previous study found that depression was one of the most important determinants of fatigue, but less is known about disease-specific factors in this patient population. This study aimed to explore the association between visual impairment severity and fatigue in adults with low vision, both directly and indirectly, with vision-specific factors and depression as potential mediators. Cross-sectional data were collected from 220 Dutch low vision service patients by telephone interviews. Fatigue was defined as a latent variable by severity and impact on daily life. Potential mediators included vision-related symptoms, adaptation to vision loss and depression. Hypothesized structural equation models were constructed in Mplus to test (in)direct effects of visual impairment severity (mild/moderate, severe, blindness) on fatigue through above mentioned variables. The final model explained 60% of fatigue variance and revealed a significant total effect of visual impairment severity on fatigue. Patients with severe visual impairment (reference group) had significantly higher fatigue symptoms compared to those with mild/moderate visual impairment (β = -0.50, 95% bias-corrected confidence interval [BC CI] [-0.86, -0.16]) and those with blindness (β = -0.44, 95% BC CI [-0.80, -0.07]). Eye strain & light disturbance, depression and vision-related mobility mediated the fatigue difference between the severe and mild/moderate visual impairment categories. The fatigue difference between the severe visual impairment and blindness categories was solely explained by eye strain & light disturbance. Moreover, depressive symptoms (β = 0.65, p < 0.001) and eye strain & light disturbance (β = 0.19, p = 0.023) were directly associated with fatigue independent of visual impairment severity. Our findings indicate an inverted-U shaped relationship between visual impairment severity and fatigue in patients with low vision. The complexity of this relationship is likely explained by the consequences of visual impairment, in particular by strained eyes and depressive mood, rather than by severity of the disability itself.