Temporal trends in the incidence and prevalence of Multiple Sclerosis in the Northwest of Spain

Prevalence of multiple sclerosis in France in 2021: Data from the French health insurance database

BACKGROUND

France is among the countries with high prevalence of multiple sclerosis (MS). The most recent estimates are from 2012 and need to be updated because MS prevalence has increased worldwide.

OBJECTIVE

To estimate MS prevalence in France on December 31, 2021 and to describe the characteristics of the French MS population using data from the French national health insurance database (SNDS).

MATERIAL AND METHODS

Persons with MS (PwMS) were identified in the SNDS database (99% of national coverage) using an algorithm with three criteria: long-term disease status, hospitalizations, and MS-specific drug reimbursements. Crude and sex- and age-stratified prevalence rates were calculated with their 95% confidence intervals as well as the standardized prevalence stratified on the region of residence.

RESULTS

In total, 134,062 PwMS were identified (71.8% of women, median age 53.0±14.8years) yielding a prevalence of 197.6 per 100,000 (95% CI [196.5-198.7]). Prevalence rates in women and men were respectively 274.9 (95% CI [273.2-276.6]) and 115.2 (95% CI [114.0-116.4]). In metropolitan France, the highest prevalence rates were observed in the northeastern regions (e.g.>230 PwMS per 100,000 in Grand Est and Hauts-de-France), and the lowest rates in the southwestern regions (∼180 PwMS per 100,000 in Nouvelle-Aquitaine and Occitanie). Overall, 32.1% of PwMS had another long-term disease and 51.8% received at least one MS-specific drug in 2021.

CONCLUSION

MS prevalence in France has increased by ∼30% in the last 10years. This increase is probably linked to population ageing, longer survival of PwMS, and the long observation period. The part attributable to a possible increase in MS risk remains to be determined with incidence studies.

The age at onset of relapsing-remitting multiple sclerosis has increased over the last five decades

BACKGROUND

Patients with relapsing-remitting multiple sclerosis (RRMS) most commonly experience their first symptoms between 20 and 40 years of age. The objective of this study was to investigate how the age at which the first symptoms of RRMS occur has changed over the past decades.

METHODS

Patients who were followed up in our unit after an initial diagnosis of RRMS using the Poser or McDonald criteria and who experienced their first symptoms between January 1970 and December 2019 were included in the study. The cohort was divided into five groups according to the decade in which the first symptoms appeared. The age at disease onset was compared across decades. Changes in age were also determined after excluding patients with early-onset disease (<18 years of age) and those with late-onset disease (>50 years of age) to avoid bias.

RESULTS

The cohort included 1,622 patients with RRMS, 67.6% of whom were women. Among them, 5.9% and 4% had early-onset and late-onset disease, respectively. The mean age ± standard deviation at onset was 31.11 ± 9.82 years, with no differences between men and women. The mean ages at onset were 23.79 ± 10.19 years between 1970 and 1979, 27.86 ± 9.22 years between 1980 and 1989, 30.07 ± 9.32 years between 1990 and 1999, 32.12 ± 9.47 between 2000 and 2009, and 34.28 ± 9.83 years between 2010 and 2019. The ages at disease onset were progressively higher in the later decades; this trend was statistically significant (p < 0.001), with a Pearson linear correlation coefficient R of 0.264 and R² of 0.070 (p < 0.001). The results were similar when analysing men and women separately. We conducted an analysis of 1,460 patients (mean age at onset: 31.10 ± 7.99 years), after excluding patients with early-onset and late-onset disease. In this specific subgroup, the mean ages at disease onset were 28.38 ± 8.17 years between 1970 and 1979, 29.22 ± 7.51 years between 1980 and 1989, 30.06 ± 8.02 years between 1990 and 1999, 31.46 ± 7.77 years between 2000 and 2009, and 33.37 ± 7.97 years between 2010 and 2019. The trend was also statistically significant (p < 0.001), with a Pearson linear correlation coefficient R of 0.193 and R² of 0.037 (p < 0.001).

CONCLUSION

Our data showed that the age at RRMS onset has increased over the past decades.