Stewart, N and Simpson Jr, S and van der Mei, I and Ponsonby, A-L and Blizzard, L and Dwyer, T and Pittas, F and Eyles, D and Ko, P and Taylor, BV, Interferon-β and serum 25-hydroxyvitamin D interact to modulate relapse risk in MS, Neurology, 79, (3) pp. 254-260. ISSN 0028-3878 (2012) [Refereed Article]
Copyright 2012 AAN Enterprises
Official URL: http://dx.doi.org/10.1212/WNL.0b013e31825fded9
OBJECTIVE: To determine whether interferon-â (IFN-â) medication use is associated with vitamin D levels and whether the two interact in exerting effects on relapse risk.
METHODS: In a prospective cohort of 178 persons with clinically definite multiple sclerosis (MS) living in southern Tasmania in 2002-2005, serum 25-hydroxyvitamin D [25(OH)D] was measured biannually, with assessment by questionnaire for relevant factors, including IFN-â treatment.
RESULTS: Subjects reporting IFN-â use had significantly higher mean 25(OH)D than persons who did not (p < 0.001). This was mediated by an interaction between personal sun exposure and IFN-â, with treated persons realizing nearly three times 25(OH)D per hour of sun exposure of persons not on therapy. The association between 25(OH)D and 1,25-dihydroxyvitamin D did not differ by IFN-â therapy (p = 0.82). 25(OH)D was associated with a reduced relapse risk only among persons on IFN-â (p < 0.001). Importantly, IFN-â was only protective against relapse among persons with higher 25(OH)D (hazard ratio [HR] 0.58 [95% confidence interval (CI) 0.35-0.98]), while among 25(OH)D-insufficient persons, IFN-â increased relapse risk (HR 2.01 [95% CI 1.22-3.32]).
CONCLUSION: In this study, we found that IFN-â therapy is associated with greater production of vitamin D from sun exposure, suggesting part of the therapeutic effects of IFN-â on relapse in MS may be through modulation of vitamin D metabolism. These findings suggest persons being treated with IFN-â should have vitamin D status monitored and maintained in the sufficiency range. Classification of evidence: This study provided Class III evidence that IFN-â is associated with reduced risk of relapse, and this effect may be modified by a positive effect of IFN-â on serum 25(OH)D levels.
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