Smoking is a known risk factor for multiple sclerosis (MS); however, how smoking affects MS progression over time remains unknown.
Since MS disease progression is usually measured by the time to conversion from relapsing-remitting to secondary-progressive MS, researchers from the Karolinska Institutet in Stockholm used this measurement to determine if continued smoking or cessation had an effect on MS disease progression.
Ryan Ramanujam, PhD, and colleagues performed a cross-sectional study of 728 MS patients who smoked at diagnosis, 332 who were classified as “continuers” who smoked continuously from the year after diagnosis and 118 who were classified as “quitters” who quit smoking the year after diagnosis. Data on 1,012 non-smoking controls was also included.
Among all participants with MS, 216 converted to secondary-progressive MS. Analysis showed that each additional year of smoking after diagnosis accelerated the conversion to secondary-progressive MS by 4.7%, with those who continued smoking after diagnosis converting faster than those who stopped smoking, reaching conversion to secondary-progressive MS at 48 and 56 years of age, respectively.
“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,” the authors wrote.
Noting that it would be impossible to rule out other confounding factors, the researchers suggest that patients who smoke and are diagnosed with MS should be encouraged to quit smoking, and should be able to do so with help from organized support outlets that can provide tools to achieve the lifestyle change.