Association between age and inflammatory disease activity on magnetic resonance imaging in relapse onset multiple sclerosis during long-term follow-up

Background and purpose: Inflammatory disease activity in multiple sclerosis (MS) decreases with advancing age. Previous work found a decrease in contrast-enhancing lesions (CELs) with age. Here, we describe the relation of age and magnetic resonance imaging (MRI) measures of inflammatory disease activity during long-term follow-up in a large real-world cohort of people with relapse onset MS. Methods: We investigated MRI data from the long-term observational Amsterdam MS cohort. We used logistic regression models and negative binomial generalized estimating equations to investigate the associations between age and radiological disease activity after a first clinical event. Results: We included 1063 participants and 10,651 cranial MRIs. Median follow-up time was 6.1 years (interquartile range = 2.4–10.9 years). Older participants had a significantly lower risk of CELs on baseline MRI (40–50 years vs. <40 years: odds ratio [OR] = 0.640, 95% confidence interval [CI] = 0.45–0.90; >50 years vs. <40 years: OR = 0.601, 95% CI = 0.33–1.08) and a lower risk of new T2 lesions or CELs during follow-up (40–50 years vs. <40 years: OR = 0.563, 95% CI = 0.47–0.67; >50 years vs. <40 years: OR = 0.486, 95% CI = 0.35–0.68). Conclusions: Greater age is associated with a lower risk of inflammatory MRI activity at baseline and during long-term follow-up. In patients aged >50 years, a less aggressive treatment strategy might be appropriate compared to younger patients.