Higher 25-hydroxyvitamin D is associated with lower relapse risk in multiple sclerosis.
OBJECTIVE
A protective association between higher vitamin D levels and the onset of multiple sclerosis (MS) has been demonstrated; however, its role in modulating MS clinical course has been little studied. We investigated whether higher levels of serum 25-hydroxyvitamin D (25-OH-D) were associated with a lower risk of relapses in people with MS.


METHODS
We conducted a prospective cohort study of 145 participants with relapsing-remitting MS from 2002 to 2005. Serum 25-OH-D levels were measured biannually, and the hazard of relapse was assessed using survival analysis.


RESULTS
There was an inverse linear relationship between 25-OH-D levels and the hazard of relapse over the subsequent 6 months, with hazard ratio (HR) 0.91 (95% confidence interval [CI]: 0.85-0.97) per 10 nmol/l increase in 25-OH-D level (p = 0.006). When variation due to timing of blood collection was removed by estimating 25-OH-D at the start of each season, this association persisted, with HR 0.90 (95% CI, 0.83-0.98) per 10 nmol/l increase (p = 0.016). Taking into account the biological half-life of 25-OH-D, we estimated 25-OH-D at monthly intervals, resulting in a slightly enhanced association, with HR 0.88 (95% CI, 0.82-0.95) per 10 nmol/l increase (p = 0.001). Adjusting for potential confounders did not alter these findings.


CONCLUSIONS
In this prospective population-based cohort study, in a cohort largely on immunomodulatory therapy, higher 25-OH-D levels were associated with a reduced hazard of relapse. This occurred in a dose-dependent linear fashion, with each 10 nmol/l increase in 25-OH-D resulting in up to a 12% reduction in risk of relapse. Clinically, raising 25-OH-D levels by 50 nmol/l could halve the hazard of a relapse.
Simpson
Steve
S
Menzies Research Institute, Hobart TAS, Australia.
Taylor
Bruce
B
Blizzard
Leigh
L
Ponsonby
Anne-Louise
AL
Pittas
Fotini
F
Tremlett
Helen
H
Dwyer
Terence
T
Gies
Peter
P
van der Mei
Ingrid
I
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*; D011446:Prospective Studies; D012008:Recurrence; D018570:Risk Assessment; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D055815:Young Adult
D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D