Impact of occupational categories on the incidence of amyotrophic lateral sclerosis in Sardinia Island, Italy

Abstract

Objective

Occupation is one of the potential risk factors for amyotrophic lateral sclerosis (ALS) for which previous controlled studies produced inconsistent results. The aim of this study is to assess the impact of several groups of occupational categories on ALS incidence.

Methods

ALS patients from the southern part of Sardinia who had onset during 2012–2021 and fulfilled El Escorial revised diagnostic criteria were included. The risk of ALS was estimated in relation to the occupation held in 2011, as obtained from the 2011 Census that classified working activities in ten groups. Each occupational group was compared with a reference category represented by all other occupations, and rate ratio were calculated. Additive interaction between activity at work and age at ALS onset/sex on ALS incidence was calculated.

Results

Employment in agriculture/breeding and in the armed forces were significantly associated with increasing ALS risk. None of the other assessed occupation groups was associated with change in the risk of ALS. Geographic analysis indicated that the effect of agriculture/breeding was particularly evident in the areas of higher risk for the general population. By contrast, an inverse pattern of spatial risk was associated with armed forces activity at work. The increased risk of ALS associated to agriculture/breeding was more evident in older people. No significant interaction was detected between working in the armed forces and older age/sex.

Conclusions

The significant interaction between agriculture/breeding and age suggests that the mechanisms leading to ALS are complex and involve several factors.

Keywords:

• Amyotrophic Lateral Sclerosis
• incidence
• epidemiology
• work
• agriculture

Authors contribution

VP designed the study, collected and analyzed data, drafted the paper. GB designed the study, collected and analyzed data, drafted the paper. FP designed the study, collected and analyzed data, drafted the paper. TE analyzed data and participated in writing and revision of the manuscript. AFG analyzed data and participated in writing and revision of the manuscript. LIL analyzed data and participated in writing and revision of the manuscript. RV analyzed data and participated in writing and revision of the manuscript. MC designed the study and participated in the conceptualization, writing and revision of the manuscript. AC designed the study and participated in the conceptualization, writing and revision of the manuscript. GD designed the study and participated in the conceptualization, writing and revision of the manuscript.

Declaration of interest

None of the authors have any potential conflicts of interest to disclose related to the manuscript.

Data availability statement

The data that support the findings of this study are available on reasonable request from the corresponding author.