Objective To explore whether age at onset increased over time despite a shortened interval from the initial clinical demyelinating event to the diagnosis of multiple sclerosis (MS), as promoted by updated diagnostic criteria. Methods This was an independent, multicentre, retrospective study based on data from 4345 patients with relapsing-onset MS attending three tertiary MS Clinics in Italy. After stratifying the year of MS onset into four periods (<1991, 1991–2000, 2001–2010, 2011–2021), we analysed the temporal trends in age at onset and interval from onset to diagnosis; we then explored the female-to-male ratio and onset location across different classes of age at onset. Results We observed an increased mean age at onset, and a shortened mean interval to diagnosis over time (p<0.0001). Accordingly, there were more MS onsets at the older age classes of 40-49, 50–59 and ≥60 years (p<0.0001). In cases with age at onset ≥40 years, we also found an increased female-to-male ratio (p=0.007), more frequent spinal cord (p=0.0004) and less frequent supratentorial onset (p=0.008). Conclusion Our study shows a forward shift towards an older age at onset of MS, thus suggesting considerable thought on the place-in-therapy of most currently used disease-modifying treatments, and on the standard of care to an older population.

Background and Objectives To estimate the proportions of patients with relapsing-remitting multiple sclerosis who despite achieving the no evidence of disease activity-3 (NEDA-3) status in the first 2 treatment years experienced relapse-associated worsening (RAW) or progression independent from relapse activity (PIRA) in the following years. Methods We selected patients with NEDA-3—defined as no relapse, no disability worsening, and no MRI activity—in the first 2 years of either glatiramer acetate or interferon beta as initial treatment. We estimated the long-term probability of subsequent RAW and PIRA (considered as 2 contrasting outcomes) by cumulative incidence functions. Competing risk regressions were used to identify the baseline (i.e., at treatment start) predictors of RAW and PIRA. Results Of 687 patients, 224 (32.6%) had NEDA-3 in the first 2 treatment years. After a median follow-up time of 12 years from treatment start, 58 patients (26%) experienced disability accrual: 31 (14%) had RAW and 27 (12%) had PIRA. RAW was predicted by the presence of >9 T2 lesions (subdistribution hazard ratio [SHR] = 3.92, p = 0.012) and contrast-enhancing lesions (SHR = 2.38, p = 0.047) on baseline MRI scan and either temporary or permanent discontinuation of the initial treatment (SHR = 1.11, p = 0.015). PIRA was predicted by advancing age (SHR = 1.05, p = 0.036 for each year increase) and presence of ≥1 spinal cord lesion on baseline MRI scan (SHR = 4.08, p = 0.016). Discussion The adoption of NEDA-3 criteria led to prognostic misclassification in 1 of 4 patients. Different risk factors were associated with RAW and PIRA, suggesting alternative mechanisms for disability accrual. Classification of Evidence This study provides Class II evidence that in patients with RRMS who attained NEDA-3 status, subsequent RAW was associated with baseline MRI activity and discontinuation of treatment and PIRA was associated with age and the presence of baseline spinal cord lesions.