Abstract
BACKGROUND: Longitudinal studies of health-related quality of life (HRQoL) in multiple sclerosis (MS) are limited. Most have examined average changes within the population, rather than dynamic changes within individuals. OBJECTIVE: To assess the between- and within-individual association between depression, anxiety, fatigue, cognition, physical functioning, and physical comorbidities and HRQoL. METHODS: Adults with MS underwent physical and cognitive assessments and reported symptoms of fatigue (Daily Fatigue Impact Scale), depression and anxiety (Hospital Anxiety and Depression Scale (HADS)), and HRQoL (RAND-36) annually (n = 4 visits). We evaluated associations of elevated symptoms of anxiety (HADS-A) and depression (HADS-D), fatigue, physical function (timed-walk and nine-hole peg test), cognitive function and comorbidity count with physical (PCS-36) and mental (MCS-36) HRQoL using multivariable linear models-estimating between-person and within-person effects. RESULTS: Of 255 participants with MS enrolled, 81.6% were women. After adjustment, within-person increases in depression and fatigue were associated with decreases in physical HRQoL. Increases in depression, anxiety, and comorbidity count were associated with decreases in mental HRQoL. CONCLUSIONS: Within-person increases in symptoms of depression, anxiety and fatigue, and comorbidity count are associated with HRQoL decreases among adults with MS, highlighting the potential magnitude of individual benefit of intervention for these symptoms.