Influence of Socio-Economic Factor on Net Survival in Patients With Multiple Sclerosis in France ( ECOVIMUS).

Background: In comparison to general population, persons with Multiple Sclerosis have a higher risk to premature death with an estimate reduced life expectancy from 7 to 14 years. However, risk factors of mortality in MS are not well identified and well known. Following the example of studies carry on cancers survival, socioeconomic status (SES) may have an influence on survival in MS.

Objective: The main objective of ECOVIMUS is to estimate net survival according to SES using the European Deprivation Index as a proxy and other major covariates (gender, initial clinical phase and years of disease onset).

Methods: In order to answer to our main objective, we will use a retrospective cohort of MS patients with a medical follow-up in one of the 18 centers included in SURVIMUS II, with a MS onset between 1960 and 2015 and with an informed vital at the date of December 31st, 2015.

The ecological score of deprivation EDI will be used as a proxy of the socioeconomic status and will be attributed from the geolocalisation to patient's residence address. Net survival is directly associated to the notion of "mortality in excess". This mortality will be estimated comparing the observed mortality in MS patients to mortality in the general population. The advantage of this methodological approach is that cause of death is not needed.

Statistical analysis: The influence of socioeconomic status on the excess of mortality will be estimated thanks to a parametric multivariate model of excess rate mortality. This model will be adjusted on other major covariates (gender, age at disease onset, and initial clinical phase) and will include potential complex effects as non-linearity, non-proportionality and interactions.

Expected results: We expect to highlight some differences of net survival in MS patients according to socioeconomic group as it was already shown in cancers. This study will complete information on factors of mortality excess in MS and knowledge on socioeconomic inequalities encountered all along MS disease course.