LONDON – Severe vitamin D deficiency and current smoking predicted accumulated disability in patients with clinically isolated syndrome, which can be a precursor to the development of multiple sclerosis.
Prospectively collected data from the ongoing Barcelona clinically isolated syndrome (CIS) cohort, which includes more than 1,000 patients with CIS, showed that patients with a serum vitamin D below 8.0 ng/mL (9% of 503 patient samples) had more than double the risk for accumulated disability when compared with those who had higher vitamin D levels. The hazard ratio for disability with severely low vitamin D levels was 2.3 (P = .049) in an analysis adjusted for the potential confounding factors of patients’ sex and age, the number of baseline T2 lesions, receipt of disease-modifying treatment, CIS topography, and oligoclonal bands. Disability accumulation was defined as an Expanded Disability Status Scale score of 3.0 or more.
However, neither vitamin D deficiency nor current smoking predicted the conversion of CIS to clinically definite multiple sclerosis (CDMS), said María Zuluaga, MD, of the Centre d’Esclerosi Múltiple de Catalunya at Vall d’Hebron University Hospital in Barcelona.
Environmental factors such as vitamin D levels and smoking have been purported to play a role in the development of CIS to CDMS, Dr. Zuluaga explained at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS).
Blood samples collected within 6 months of a diagnosis of CIS were examined and vitamin D deficiency defined as normal, mild, moderate, or severe based on serum 25-hydroxy vitamin D of greater than 20, 16-20, 8-15, and less that 8 ng/mL.
Levels of the nicotine metabolite cotinine in the blood were used as a proxy for current smoking. Cotinine has a half-life of around 20 hours and smokers – active or passive – have a level of 14 ng/mL or more while nonsmokers have a level of less than 14 ng/mL.
The study received no commercial funding. Dr. Zuluaga reported having no conflict of interest related to the study.