Objective:

The objective of this systematic review was to describe the global incidence and prevalence of Amyotrophic Lateral Sclerosis (ALS).

Background:

ALS is a rare neurodegenerative disorder affecting upper and lower motor neurons. Due to the rarity and rapidly progressive nature of the disease, studying the epidemiology of ALS is challenging and a comprehensive picture of the global burden of this disease is lacking.

Design/Methods:

We searched Medline, Embase, Global Health, PsycInfo, Cochrane Library, and CINAHL to identify articles published between January 1^st, 2010, and May 6^th, 2021. Articles that were population-based and reported estimates of prevalence, incidence, and/or mortality of ALS, were eligible for inclusion into this review. This paper focuses on incidence and prevalence results. Quality assessment was performed using a tool developed to evaluate methodology relevant to epidemiological research. This review was registered with PROSPERO, CRD42021250559.

Results:

This search generated 6,238 articles, of which 140 articles were selected for data extraction and quality assessment. Of these, 85 articles reported on incidence and 61 on prevalence of ALS. Incidence ranged from 0.26 per 100,000 person-years in Ecuador to 23.46 per 100,000 person-years in Japan. Point prevalence ranged from 1.57 per 100,000 in Iran to 11.80 per 100,000 in the United States. Many articles identified ALS cases from multiple data sources. Nearly half of the European studies utilized data from ALS registries.

Conclusions:

There is variation in reported incidence and prevalence estimates of ALS across the world. While registries are an important and powerful tool to quantify disease burden, such resources are not available everywhere. This results in gaps in reporting of the global epidemiology of ALS, as highlighted by the degree of variation (and quality) in estimates of incidence and prevalence reported in this review.