The impact of fatigue and psychosocial variables on quality of life for patients with motor neuron disease.

Our objective was to evaluate the direct and indirect relationships between psychosocial variables, fatigue and quality of life for patients with motor neuron disease (MND). A cross-sectional sample of 147 MND patients was recruited from five neurological care centres in England. Variables included anxiety, coping, depression, fatigue, functional status, social withdrawal and quality of life. Direct and indirect relationships between study variables were assessed using structural equation modelling (SEM), using linear values derived from Rasch analyses of study questionnaires. Following some modification, Rasch analysis confirmed the suitability of all measures for use in this population. The final SEM model consisting of anxiety, coping, depression, fatigue, social withdrawal and quality of life showed excellent fit to the data. The model accounted for 59% of the variance in quality of life and 50% of the variance in depression. In conclusion, our data support a model that explains a large degree of the variance in quality of life for MND patients. Coping was most strongly related to quality of life, with the largest proportion of its influence mediated by anxiety and depression. Significant direct effects upon quality of life were exhibited by depression, fatigue and social withdrawal.