Effects of age and disease duration on excess mortality in patients with multiple sclerosis from a French nationwide cohort

Objective: To determine the effects of current age and disease duration on excess mortality in multiple sclerosis, we described the dynamics of excess deaths rates over these two time scales and studied the impact of age at multiple sclerosis clinical onset on these dynamics, separately in each initial phenotype.

Methods: We used data from 18 French multiple sclerosis expert centers participating in the Observatoire Français de la Sclérose en Plaques. Patients with multiple sclerosis living in metropolitan France and having a clinical onset between 1960 and 2014 were included. Vital status was updated on January 1st, 2016. For each multiple sclerosis phenotype separately (relapsing onset (R-MS) or primary progressive (PPMS)), we used an innovative statistical method to model the logarithm of excess death rates by a multidimensional penalized spline of age and disease duration.

Results: Among 37524 patients (71% women, mean age at multiple sclerosis onset ± standard deviation 33.0 ...