van der Vuurst de Vries RM, et al. - This study was pursued in order to gauge the risk of clinically definite multiple sclerosis (CDMS) in smoking and non-smoking clinically isolated syndrome (CIS) patients at the time of a first demyelinating event. Data illustrated that smoking at the time of CIS appeared to be an independent risk factor for a future CDMS diagnosis. This finding served as an additional argument to quit smoking at the time of the first attack of suspected MS.