Epidemiology, genetics, clinical features and survival of Amyotrophic lateral sclerosis in Latin American and the Caribbean: a systematic review
Résumé
Introduction: Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disease. The evidence suggests heterogeneity between geographic areas and populations in terms of epidemiology, genetics and phenotypes (1–3). However, there is limited information of ALS in Latin America. We conducted a systematic review that aimed to describe epidemiology, frequency of genetic mutations, clinical characteristics, and survival of ALS in this region.
Methods: We reviewed Medline, Scopus, Scielo and LILACS databases up to April 2020, using the following search terms “Amyotrophic lateral sclerosis”, or “Motor neuron disease” in combination with the list of Latin American countries from the United Nations. Observational studies were included with no time and language limitations. A methodological analysis was performed using the basic principles of descriptive epidemiology.
Results: A review of 1036 records identified 36 studies, covering 13 Latin American countries. According to the original reports, ALS occurrence varied widely from country to country with a standardized incidence (1990 US population) ranging from 0.3 per 100,000 person-years follow up (PYFU) in Ecuador to 3.6 per 100,000 PYFU in Uruguay. A low proportion of the C9orf72 expansion was reported in Cuba and Brazil. We identified specific clinical characteristics: i) age at onset was between 50 and 60 years; ii) bulbar onset was broadly variable ranging from 10% to 40%; iii) survival time was higher than 40 months in half of the studies. Data from multiethnic populations reported a higher risk of developing ALS in Caucasians compared to Admixed and Black populations.
Conclusion: This review provides an overall perspective of ALS variability across Latin America and highlights specific differences when comparing to European and North America countries. Nevertheless, we cannot draw firm conclusions because of different methodological concerns and bias within the studies. Finally, there is a need of original studies with standard methodology in Latin America.