Our data support previous observations that smoking is a modifiable risk factor for secondary progressive MS and confirms that spinal cord involvement, age, and more severe disease at onset are prognostic factors for converting to secondary progressive MS. https://www.sciencedirect.com/science/article/abs/pii/S2211034821003825?fbclid=IwAR38BZUo3Rnbb4aIj6cywLElmT8mf2ESRAMKGUop_2rJTl3jp9rBRLwbQiI_aem_AXpOR-D2cxYBtd7Kt45nbOqy9FCb8XbINIwwurtkeMx7nbX7j7G3WZzx5EM2cGqSIWg