Their study, “Predicting the course of CIS patients adding modifiable environmental factors such as smoking and vitamin D,” was presented at the 34th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) on Oct. 11 in Berlin.
The team, led by researchers at the Cemcat-Vall Hebron University Hospital in Spain, constructed a mathematical model to predict long-term outcomes (prognosis) in CIS patients. One of the study’s main goals was to estimate how environmental factors, specifically smoking and vitamin D levels, might affect CIS prognosis.
There is growing evidence that both are relevant risk factors for multiple sclerosis (MS) onset and severity.
The model was based on more than 1,050 patients with more than one year of clinical assessment and brain MRI data. First, researchers predicted the hazard of disease progression based on age, sex, disease manifestations, protein markers of neuroinflammation, and the number of brain lesions (T2) seen on MRI scans.
Patients were then separated into three risk groups according to their predicted median time to reach a disability score of 3.0 in EDSS scale: low risk (442 patients); medium risk (561 patients; risk three times higher than the low group); and high risk (51 patients; 9.6 times higher risk than the low group).
Then, researchers looked at how the patients’ predicted risk changed after taking into account vitamin D deficiency and smoking (cotinine levels in serum were used as surrogate markers of smoking).
Vitamin D deficiency — present in 472 patients — increased the predicted risk of disability worsening. Including this deficiency in the model moved low-risk patients into medium-risk group, and those with medium risk to high risk. Among the 51 CIS patients already considered to be at high risk, the impact of vitamin D insufficiency was minor.
Smoking also increased the risk of disability worsening. Those with high cotinine levels had higher chances of EDSS progression (cotinine being a biomaker of tobacco exposure). Accounting for smoking in the model increased the estimated risk of low-risk patients moving it to medium-risk, and of those at medium-risk to high-risk.
For those already at high-risk, smoking raised the chance of worse outcomes from 13.8-fold to 64.2-fold, compared with those in the low-risk reference group.
Overall, the team concluded that “smoking and low vitamin D levels are key modifiable prognostic factors that show a dramatic interaction with risk of EDSS progression,” they wrote.
“Design of preventive strategies is warranted,” the team added.