Could Smoking Accelerate the Progression of MS?

A new study finds that continuing to smoke after receiving a diagnosis of multiple sclerosis (MS) may hasten the disease’s progression.

The cross-sectional study included 728 patients with MS who smoked, as well as 1,012 MS patients who did not smoke. Patients were identified from a Swedish national MS registry, with the authors collecting patient environmental data via questionnaire. Among patients in the smoking group, 322 were classified as “continuers,” or those who smoked at least 1 cigarette daily in the year after they received their diagnosis, while 118 were considered “quitters” who stopped smoking within a year of diagnosis. The remaining 278 were intermittent smokers, and were not considered in the primary outcome.
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Overall, patients who continued to smoke converted to secondary progressive MS at an average age of 48, while those who quit reached that stage at the age of 56, corresponding to a 4.7% acceleration in time to onset of secondary progression. The authors note, however, that they found no difference in the age at conversion to secondary progressive MS when comparing patients who smoked at the time of initial diagnosis to those who had never smoked. This finding, they say, may suggest that pre-diagnosis smoking may affect risk but not disease course.

“We already knew that smoking, even passively, increased the risk of MS,” says co-author Jan Hillert, MD, PhD, who heads the department of clinical neuroscience at the Karolinska Institutet.

This study, however, “is the first to indicate that it matters whether you continue [smoking] once you get the diagnosis,” he says. “The message is clear: Those who stop fare better over the coming 10 to 20 years. To put this into perspective, this is the kind and size of effect that we hope our disease-modifying drugs for MS have, but evidence for that are still not conclusive.”

—Mark McGraw

Reference

Ramanujam R, Hedstrom AK, et al. Effect of Smoking Cessation on Multiple Sclerosis Prognosis. JAMA Neurol. 2015.