The Role of Social and Territorial Inequalities in the Management and Prognosis of Multiple Sclerosis - Longitudinal Observational Study - INESEP

Although the majority of the French population is covered by social security, the effects of social inequalities on health are still very visible and are even increasing in France and in Europe. Thus, according to INSEE, excess mortality is observed among the most disadvantaged populations. Similarly, the prevalence of certain chronic diseases in France and Europe, particularly cardiovascular diseases, is linked to social inequalities and excess morbidity can be observed in the most disadvantaged populations.

In addition to social inequalities, which refer to disparities in health levels according to social category, there are the effects of territorial inequalities. In France, there are geographical areas of excess mortality, which essentially correspond to areas far from urban centers. Similarly, there are major geographical differences in terms of medical supply and equipment, and the distance between patients and health centers is a direct obstacle to the use of the health care network.

The underlying explanations for social inequalities in health are multiple. While it is likely that difficulties in accessing and using care play a role, it is also possible that they are due to differences in exposure to certain environmental (e.g. pollution) or individual (e.g. smoking) risk factors. But it is also possible that the causal relationship is the opposite and that diseases create or reveal social inequalities.

For multiple sclerosis (MS) the impact of social and territorial inequalities is more debated. Indeed, with regard to the relationship between disease prevalence and social inequalities, a recent literature review found 21 separate studies on the subject, of which 13 failed to show a link between socioeconomic status and MS risk, 5 concluded that there was an increased risk of MS in advantaged populations and 3 concluded that there was an increased risk of MS in disadvantaged populations. There are plausible pathophysiological explanations for either direction of the relationship, but the question remains open.

To our knowledge, the link between MS prognosis and social inequalities has been little studied, as disadvantaged populations are more often exposed to the poor prognostic factor of smoking [6-8], the hypothesis of a negative prognostic role of social inequalities remains plausible. Similarly, the current consensus is that the diagnosis and treatment of MS should be as early as possible [9,10] in order to preserve brain capital. Easy access to a neurologist and MRI are therefore potentially prognostic factors for MS in relation to territorial inequalities. It should be noted that the link between social and geographical inequalities and a potential delay in treatment has not been demonstrated in France in the case of cancer, but it is possible that the importance of the means implemented in the fight against cancer erases these effects. In MS, a study showed a link between delay in starting a second disease-modifying therapy and socio-economic status.

While the causal link between MS and socio-professional status has not yet been demonstrated, the socio-economic impact of MS has been measured. In particular, it has been shown that having MS is associated with an increased risk of unemployment and/or early retirement.

The primary objective of our study is to determine whether delay in treatment, as a marker of difficulties in access to care in MS, is associated with social and territorial inequalities in MS. Secondary objectives will be to explore the link between MS prognosis and social and territorial inequalities.

Exposure to sunlight is a known protective factor and is consistent with the north-east-south-west gradient observed in France. The choice of centers associated with the research, spread over the French territory, will make it possible to monitor and measure this effect in the prognosis of MS.

As the available treatments have evolved considerably over the last ten years, and in order to avoid a period effect, the patients recruited in the study will have to have a date of onset of the disease after 1 January 2009.

Primary objective Determining the relationship between socio-economic inequalities and the time to start disease-modifying therapy in MS Secondary objective

1. To determine the relationship between geographical inequalities and delay in starting disease-modifying therapy in MS
2. To determine the relationship between socio-economic inequalities and time to walking disability (EDSS 4)
3. To determine the relationship between geographical inequalities and time to walking disability (EDSS 4)
4. To measure the impact of disability on socioeconomic status in MS patients