MS Relapse, Worse Disease More Likely for Smokers: New Study

People with relapsing-remitting multiple sclerosis (RRMS) who are receiving oral disease-modifying therapies (DMTs) are still more likely to experience a relapse or any form of disease activity if they are smokers, a study found.

Researchers also observed that former smokers had a disease course that was very similar to that of people who had never smoked before.

“There was no significant difference in the survival curves of relapse or any disease activity between the two groups, suggesting that smoking history before initiating oral [DMTs] in former smokers did not affect the subsequent disease course or effect of [DMTs],” the team wrote.

Therefore, multiple sclerosis (MS) patients “should be advised to stop smoking” even after they have been started on DMTs, the researchers wrote.

The study, “Effect of smoking on disease activity in multiple sclerosis patients treated with dimethyl fumarate or fingolimod,” was published in the journal Multiple Sclerosis and Related Disorders.

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July 7, 2022 News by Lindsey Shapiro, PhD

Smoking Linked to Worse Outcomes in RRMS Patients After 10 Years

Smoking linked to MS relapse, disease activity

In MS patients, the immune system mistakenly attacks part of the brain and the spinal cord, causing a range of symptoms. It is well known that smoking can increase the risk of developing MS and also is a risk factor for poorer prognosis in patients who have the disease.

However, whether smoking also increases the risk of relapses or radiological disease activity, especially in patients receiving oral DMTs, remains unclear. To date, only one study in a Caucasian population reported that smoking may have an impact on the effectiveness of oral medications, but similar reports in Asian populations are lacking.

To know more, a team of researchers in Japan examined the medical records of 103 people with RRMS who were given DMTs. These patients received either Gilenya (fingolimod) or Tecfidera (dimethyl fumarate) from 2012 to 2019 at a single center.

At the start of treatment, 19 patients (18.4%) were current smokers. and most of them (15, or 78.9%) continued smoking until the end of the study’s observation period. Of the 84 non-smokers, 23 (27.4%) were former smokers and 61 (72.6%) had never smoked before.

The proportion of women was significantly lower among smokers than among non-smokers (52.6% vs. 83.3%). Also, among non-smokers, never-smokers had a higher percentage of women than former smokers (90.2% vs. 65.2%).

During the follow-up period, a total of 27 patients (26.2%) experienced a relapse and 49 (47.6%) had any form of disease activity — either a relapse or the appearance of new lesions on MRI scans.

Results showed that the incidence of relapses was higher in smokers than in non-smokers (47.4% vs. 21.4%), as was the percentage of patients who experienced any form of disease activity (79% vs. 40.5%).

The time from the start of treatment to experiencing relapse also was significantly shorter in smokers than non-smokers, with smokers being 2.72 times more likely to experience a relapse over the observation period. Smokers also were more than twice as likely to experience any form of disease activity.

MS patients should be advised to stop smoking even after initiation of oral [DMTs]

The researchers theb divided the non-smokers into former and never-smokers. But the chance of having a relapse or experiencing any form disease activity was similar for former smokers and those who had never smoked before.

After taking into account a number of parameters, such as age, sex, and disease activity at the start of treatment, smoking stood out as an independent risk factor for relapse and disease activity in people receiving oral DMTs.

People on treatment with Tecfidera tended to have a higher rate of relapse than those receiving Gilenya, but the difference was not significant.

These findings led researchers to conclude their study with a word of warning for patients.

“MS patients should be advised to stop smoking even after initiation of oral [DMTs],” they wrote, adding, “Education about smoking cessation is necessary for patients with RRMS under [disease-modifying medications] who smoke.”