LYON, FRANCE—Smoking is associated with an increased risk for multiple sclerosis (MS), according to Jonathan Salzer, MD, from the Department of Neurology at Umeå University in Sweden, and colleagues, who reported their study findings at the 28th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS). They found that elevated cotinine levels in serum and plasma samples drawn a median of nine years prior to disease onset were associated with a 50% increased risk for MS. The effect was only evident in those under a median age of 26.4. The association, the researchers said, became slightly stronger when excluding users of smokeless tobacco.
Dr. Salzer and colleagues sought to investigate the effects of laboratory-defined tobacco use on the risk for MS using prospectively collected biobank blood samples. Their nested case-control study was performed in northern Sweden, and used two population-based biobank cohorts to identify blood samples collected before MS onset. Levels of cotinine, a recognized biochemical marker for tobacco use, were measured using an immunoassay. Self-reported questionnaire data on tobacco use were collected retrospectively.
The researchers found that elevated cotinine levels (≥10 ng/ml) were associated with a significantly increased risk for MS (odds ratio, 1.5). This association was most pronounced in young individuals (below median age at blood sampling, <26.4 years). No dose-response effect was evident. The findings were replicated by retrospective smoking questionnaire data.
—Glenn S. Williams