Modelling the effect of improving access to MRI on natural history of multiple sclerosis

<h3></h3> The prognosis of multiple sclerosis (MS) has improved. This study investigates the effect of improved MRI access on MS prognosis. This retrospective cross-sectional study included (n = 223) people with MS (pwMS) who had their initial MRI between 2006 and 2023. Total lesion volume (cm3) and count on the initial MRI were calculated. Time from symptom onset to initial scan (days) was recorded. Age-related MS Severity Score (ARMSS) and MS Severity Score (MSSS), or Expanded Disability Status Scale (EDSS) adjusted for age and disease duration, respectively, were measured. Multivariable regression was used for analysis. The year of initial MRI was not associated with lesion number (β=0.01 [-0.510, 0.531]), total lesion volume (β=0.07 [-0.155, 0.018]), or time to initial scan (β=-23.33 [-54.6, 7.94]). PwMS with initial scan ≥2018 (n = 64) had lower ARMSS (β=-2 [-2.8, -1.1]) and MSSS (β=-1.1 [-2, -0.1]) than pwMS with initial scan ≤2009 (n = 66). The diagnosis of pwMS, in terms of earlier diagnosis or less radiological burden, has not changed over the past 17 years. However, disability outcomes of pwMS have improved within this time. Other factors, such as disease-modifying therapies, may be contributing to the improved MS prognosis rather than better MRI access.