Accumulative risk of clinical event in high-risk radiologically isolated syndrome in Argentina: data from the nationwide registry RelevarEM

We aimed to analyze the accumulative risk of MRI and OB factors for evolution from RIS to MS in subjects included in the Argentinean MS registry (NCT03375177). RIS subjects were identified according to RIS diagnosis criteria. Subjects were longitudinally followed with clinical and MRI at intervals of 6 months. Time from RIS identification to the first clinical event was estimated using Kaplan–Meier. Multivariable Cox regression models were created to assess the independent predictive value of demographic characteristics, as well as clinical, OB and MRI data on time to the first clinical event. The single and increased risk factor of evolution of RIS was quantified. A total of 88 RIS subjects, mean follow-up time 42 ± 4 months were included. 39 (44.3%) and 23 (26.1%) had a new MRI lesion or a clinical event, respectively, during the follow-up. OB (HR 5.9, 95% CI 1.29–10.1, p = 0.004), infratentorial lesions (HR 3.7, 95% CI 1.09–7.5) and spinal cord lesions (HR 5.3, 95% CI 1.4–8.2, p = 0.01) at RIS identification were independent predictors associated with a subsequent clinical event. The accumulative risk showed that when two of the three factors (OB, infratentorial or spinal cord lesions) were present the HR was 10.4, 95% CI 4.4–22, p