Motor neuron disease in France (2010-2021): incidence, mortality, and spatial disparities

Background

Motor Neuron Diseases (MND), primarily Amyotrophic Lateral Sclerosis, are neurodegenerative disorders with severe prognosis. Given their potential link to environmental risk factors, establishing a robust description of their frequency at a fine scale is essential. This study aims to describe the incidence and mortality of MND in France between 2010 and 2021 and investigate whether areas of higher incidence exist across the country.

Methods

Incident cases and deaths were identified from the « French National Health Data System » (including health insurance and hospital data) using a validated algorithm and medical causes of death. Standardized incidence and mortality rates were calculated. Spatial analysis was performed at the inter-municipal level (N = 1,251) using Bayesian hierarchical models (BYM2) and spatio-temporal scanning (SaTScan™) to identify potential clusters.

Results

Between 2010 and 2021, approximately 2,250 incident cases and 1,840 deaths were recorded annually. Standardized incidence (3.0–3.5/100,000 person-years) and mortality (2.7–3.0/100,000) remained stable. Risk was higher in men and peaked in the 70-79 age group. Spatial analysis revealed significant geographical heterogeneities, identifying specific inter-municipal areas with higher-than-expected incidence and several localized clusters.

Conclusions

This study provides the first comprehensive description of the geographical distribution of MND in France over an 11-year period. These findings offer crucial insights to support the organization of healthcare services. While standardized incidence and mortality remained stable over the decade, the identification of localized geographical heterogeneities at the inter-municipal level suggests potential areas of interest for further investigation. This represents a first step toward exploring possible risk factors through further etiological research.

Key messages

• Standardized MND incidence and mortality remained stable in France (2010-2021). The observed raw increase is likely related to population ageing rather than a shift in disease dynamics.

• High-resolution spatial analysis identified local geographical heterogeneities, providing a valuable basis for planning healthcare services and guiding future research on potential risk factors.