MS may progress more quickly in smokers

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - Smokers with multiple sclerosis (MS) may have faster disease progression compared with those who quit, new research shows.

Continued smoking speeds the time to secondary progressive MS, so patients should be advised to stop smoking as soon as they are diagnosed with MS, and health care services should be organized to support their efforts, the study authors advised.

"The most important finding of this study is simply that quitting smoking following the diagnosis of MS is protective," Dr. Myla D. Goldman of the University of Virginia, Charlottesville, told Reuters Health by phone.

"Previous research had clearly demonstrated that there was an association between the risk of MS and the likelihood of developing MS based on smoking history when factored into other risk factors, but what wasn't known is whether, once you have MS, if quitting smoking would be beneficial. That's what makes this study unique," said Dr. Goldman, who coauthored an editorial on the report.

"We say to patients all the time, 'You should quit smoking because we know it's bad for you,' and they continue to smoke. But if we can say to a patient, 'You should quit smoking because there was a study that demonstrated that quitting smoking had a benefit in terms of time of onset to secondary progression, and that benefit was X number of years,' it's more concrete and more personalized to that individual and, I think, has a greater impact on the likelihood for success," she added.

For their study, Dr. Jan Hillert and colleagues from the Karolinska Institute in Stockholm used the Swedish National MS Registry to do a three-year cross-sectional study of 728 patients with MS who smoked at diagnosis.

The 332 "continuers" smoked continuously from the year after diagnosis, while the 118 "quitters" stopped smoking the year after diagnosis. The remaining 278 were categorized as "intermittent" smokers.

According to an "optimized model" the investigators created, each additional year of smoking after diagnosis accelerated the time to conversion to secondary progressive MS by 4.7% (p<0.001).

In addition, patients who smoked continuously each year after diagnosis converted to secondary progressive MS at a median age of 48 compared with the quitters' median of 56, according to an article online September 8 in JAMA Neurology.

"We used to know that smoking increased the risk of getting MS," Dr. Hillert told Reuters Health by email. "Now we know that smoking is also bad once you have MS. This is maybe expected but these results allow us to update our advice to MS patients: Stop smoking now."

"The scale of the negative influence is surprisingly large," he noted. "The prospects are almost twice as bad if you continue smoking, or just half as bad if you stop."

SOURCE: http://bit.ly/1EUdkh4 and http://bit.ly/1MeTEqQ

JAMA Neurol 2015.

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