Continued smoking after a diagnosis of multiple sclerosis appears to be associated with accelerated disease progression compared with those patients who quit smoking, according to a study.
Findings were published Sept. 8 on the website of JAMA Neurology.
MS is a neurogenerative disease, and smoking is one of its known risk factors, according to the National Multiple Sclerosis Society. While MS begins with an initial course of irregular and worsening relapses, it usually changes after about 20 years into secondary progressive disease. The time from onset to conversion to SPMS is a frequently used measure of disease progression, according to a news release.
Jan Hillert, MD, PhD, of the Karolinska Institutet at Karolinska University Hospital Solna, Stockholm, and coauthors studied 728 patients in Sweden with MS who smoked at diagnosis, of whom 216 converted to SP. Among the 728 smokers, 332 were classified as continuers who smoked continuously from the year after diagnosis and 118 were quitters who stopped smoking the year after diagnosis. Data on 1,012 people who never smoked also were included in the study. Nearly 60% of patients with MS were smokers in the present study cohort and in a Swedish cohort of new cases, according to study background.
Analysis by the authors suggests each additional year of smoking after diagnosis accelerated the time to SP conversion by 4.7%. Other analysis suggested those patients who continued to smoke each year after diagnosis converted to SP earlier, at age 48, than those who quit, who converted to SP at age 56.
The authors noted it is impossible to rule out other confounding factors.
“This study demonstrates that smoking after MS diagnosis has a negative impact on the progression of the disease, whereas reduced smoking may improve patient quality of life, with more years before the development of SP disease,” they wrote. “Accordingly, evidence clearly supports advising patients with MS who smoke to quit. Healthcare services for patients with MS should be organized to support such a lifestyle change.”
In a related commentary, Myla D. Goldman, MD, of the University of Virginia, Charlottesville, and Olaf Stüve, MD, PhD, of the University of Texas Southwestern Medical Center at Dallas, wrote that the study adds to research showing smoking in an important modifiable risk factor for MS.
“Most importantly, it provides the first evidence, to our knowledge, that quitting smoking appears to delay onset of secondary progressive MS and provide protective benefit,” they wrote in the editorial. “Therefore, even after MS diagnosis, smoking is a risk factor worth modifying.”