Multiple sclerosis (MS) is an autoimmune condition of the central nervous system. Sun exposure and vitamin D are associated with MS onset and progression and may affect quality of life (QoL).
To investigate the prospective relationship of sun exposure and vitamin D supplement use with QoL and change thereof from baseline to 2.5 years follow-up in an international cohort of people with MS.
Sun exposure and vitamin D supplement use were queried at both timepoints. QoL was assessed by MSQOL-54, estimating physical and mental health QoL composite scores, and subdomains within each. Characteristics of QoL at follow-up were assessed by linear regression, adjusted for age, sex, socioeconomic status, comorbidity number, MS type, disability, fatigue, prescription antidepressant medication use, and ongoing relapse symptoms. Baseline predictors of change in QoL were additionally adjusted for baseline QoL score.
Mean baseline QoL composite scores were 61.99 for physical (n=1155) and 70.29 for mental (n=1316) QoL composite score, materially unchanged at follow-up. QoL scores were higher among those taking vitamin D supplements (physical: aβ=3.44, 95% CI=1.17-5.71; emotional: aβ=3.14, 95% CI=0.76-5.51); higher supplementation frequency and dose were more strongly associated with both. Baseline vitamin D supplementation was associated with greater increase in physical (aβ=1.06, 95% CI=0.26-1.86), but not mental health (aβ=0.16,95%CI=-0.96,1.28), QoL. Sun exposure was cross-sectionally associated with higher QoL scores but not with change in QoL.
Vitamin D supplementation, particularly average daily doses over 5000IU/d, were associated with higher QoL and with an increase in physical QoL.