Vitamin D Status Does Not Affect Disability Progression of Patients with Multiple Sclerosis over Three Year Follow-Up

Background and Objective The risk of developing multiple sclerosis (MS) as well as MS disease activity is associated with vitamin D (25(OH) D) status. The relationship between the main functional disability hallmark of MS, disability progression, and 25(OH) D status is less well established though, especially not in MS patients with progressive disease. Methods This retrospective follow-up study included 554 MS patients with a serum baseline 25(OH) D level and Expanded Disability Status Scale (EDSS) with a minimum follow-up of three years. Logistic regressions were performed to assess the effect of baseline 25(OH) D status on relapse rate. Repeated measures linear regression analyses were performed to assess the effect on disability and disability progression. Results Baseline deseasonalized 25(OH) D status was associated with subsequent relapse risk (yes/no), but only in the younger MS patients (<= 37.5 years; OR = 0.872, per 10 nmol/L 25 (OH) D, p = 0.041). Baseline 25(OH) D status was not significantly associated with either disability or disability progression, irrespective of MS phenotype. Conclusion Within the physiological range, 25(OH) D status is just significantly associated with the occurrence of relapses in younger MS patients, but is not associated with disability or disability progression over three years follow-up. Whether high dose supplementation to supra physiological 25(OH) D levels prevents disability progression in MS should become clear from long term follow-up of supplementation studies.