3158 Nitrous oxide myelopathy: a case series

natalizumab, 3.1% from alemtuzumab and 27.7% from oral DMTs.The reasons for switching DMT to OFA included scheduled stop (13.1%), evidence of disease activity (9.1%), convenience (6.9%), side effects/intolerance (6.2%), JCV antibody positive (2.8%), pregnancy planned/confirmed (2.5%) and not reported (37.2%).The median age of patients initiating OFA was 42.67 [36.65, 51.98] years, with a median disease duration of 9. 19 [3.61, 17.11] years and median EDSS of 2 [1.5, 3.5]. ConclusionThe real-world data from this secondary use of data MSBase registry analysis provides a valuable snapshot of the Australian experience of relapsing MS patients initiated on OFA, with 22% of patients treated as first line therapy.