Incidence and prevalence of amyotrophic lateral sclerosis in an HMO of Buenos Aires, Argentina

Incidence of amyotrophic lateral sclerosis in Chile

OBJECTIVE

This study aimed to estimate amyotrophic lateral sclerosis (ALS) incidence and survival rates in the Metropolitan region of Chile.

METHODS

We conducted a cohort study of ALS cases in the Metropolitan Region from 2016 to 2019. A total of 219 ALS patients were recruited from Corporación ELA-Chile registry, in collaboration with neurologists from Sociedad de Neurología, Psiquiatría y Neurocirugía de Chile. We calculated incidence rates by sex and age and determined median survival from onset and diagnosis. Survival analysis used the Kaplan-Meier statistic, estimating hazard ratios for age, sex, time from symptom onset and from diagnosis using a Weibull regression model. All analyses were done using R 4.1.0.

RESULTS

Overall, ALS diagnosis incidence was 0.97 cases per 100,000 inhabitants, peaking in the 70-79 age group and declining thereafter. The male-to-female ratio was 1.23. The median time to death from diagnosis was 2.3 years (95% confidence interval [CI]: 1.9-2.5), and from the first symptom, it was 3.1 years (95% CI: 2.8-3.5).

CONCLUSIONS

This is the first population-based study reporting ALS incidence and survival rates in Chile's Metropolitan region. Incidence resembled other Latin American studies. Median survival from diagnosis and from the first symptom were in line with previous findings. Our results corroborated lower ALS rates in Latin America, consistent with prior research.

Global Prevalence and Incidence of Amyotrophic Lateral Sclerosis: A Systematic Review

BACKGROUND AND OBJECTIVES

Amyotrophic lateral sclerosis (ALS) is a rare neurodegenerative disorder affecting upper and lower motor neurons. Due to its rarity and rapidly progressive nature, studying the epidemiology of ALS is challenging, and a comprehensive picture of the global burden of this disease is lacking. The objective of this systematic review was to describe the global incidence and prevalence of ALS.

METHODS

We searched MEDLINE, Embase, Global Health, PsycInfo, Cochrane Library, and CINAHL to identify articles published between January 1, 2010, and May 6, 2021. Studies that were population based and reported estimates of prevalence, incidence, and/or mortality of ALS were eligible for inclusion. This study focuses on the incidence and prevalence. Quality assessment was performed using a tool developed to evaluate methodology relevant to prevalence and incidence studies. This review was registered with PROSPERO, CRD42021250559.

RESULTS

This search generated 6,238 articles, of which 140 were selected for data extraction and quality assessment. Of these, 85 articles reported on the incidence and 61 on the 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 cases with ALS from multiple data sources.

DISCUSSION

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.

Estimated Prevalence and Incidence of Amyotrophic Lateral Sclerosis and SOD1 and C9orf72 Genetic Variants

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a rare neurological disorder characterized by progressive deterioration of motor neurons. Assessment of the size/geographic distribution of the ALS population, including ALS with genetic origin, is needed to understand the burden of the disease and the need for clinical intervention and therapy.

OBJECTIVES

The main objective of this study was to estimate the number of prevalent and incident ALS cases overall and superoxide dismutase 1 (SOD1) and chromosome 9 open reading frame 72 (C9orf72) ALS in 22 countries across Europe (Belgium, France, Germany, Ireland, Italy, Netherlands, Norway, Russia, Spain, Sweden, and UK), North America (USA and Canada), Latin America (Argentina, Brazil, Colombia, Mexico, and Uruguay), and Asia (China, Japan, South Korea, and Taiwan).

METHODS

A comprehensive literature search was conducted to identify population-based studies reporting ALS prevalence and/or incidence rates. Pooled prevalence and incidence rates were obtained using a meta-analysis approach at the country and regional geographic level. A country-level pooled estimate was used when ≥2 studies were available per country and geographic regional pooled estimates were used otherwise. The proportion of cases with a SOD1 or C9orf72 mutation among sporadic (sALS) and familial (fALS) cases were obtained from a previous systematic review and meta-analysis.

RESULTS

Pooled prevalence rates (per 100,000 persons) and incidence rates (per 100,000 person-years) were 6.22 and 2.31 for Europe, 5.20 and 2.35 for North America, 3.41 and 1.25 for Latin America, 3.01 and 0.93 for Asian countries excluding Japan, and 7.96 and 1.76 for Japan, respectively. Significant heterogeneity in reported incidence and prevalence was observed within and between countries/geographic regions. The estimated number of 2020 ALS cases across the 22 countries is 121,028 prevalent and 41,128 incident cases. The total estimated number of prevalent SOD1 cases is 2,876 cases, of which, 1,342 (47%) were fALS and 1,534 (53%) were sALS, and the number of incident SOD1 cases is 946 (434 [46%] fALS and 512 [54%] sALS). The total estimated number of prevalent C9orf72 cases is 4,545 (1,198 [26%] fALS, 3,347 [74%] sALS), and the number of incident C9orf72 cases is 1,706 (450 [26%] fALS and 1,256 [74%] sALS).

DISCUSSION

The estimated number of patients with SOD1 and C9orf72 ALS suggests that although the proportions of SOD1 and C9orf72 are higher among those with fALS, the majority of SOD1 and C9orf72 ALS cases may be found among those with sALS (about 53 and 74%, respectively). These results suggest that classification of fALS based on reported family history does not capture the full picture of ALS of genetic origin.

Epidemiological and genetic features of amyotrophic lateral sclerosis in Latin America and the Caribbean: a systematic review

Introduction: Heterogeneity of amyotrophic lateral sclerosis (ALS) has been suggested in terms of epidemiology, phenotypes and genetics between geographic areas and populations. However, there is limited information in Latin America. We conducted a systematic review that aimed to describe the epidemiology, frequency of genetic mutations, clinical characteristics and survival of ALS patients in this region. Methods: We reviewed Medline, Scopus, Scielo and LILACS databases up to April 2020. The search terms "Amyotrophic Lateral Sclerosis" or "Motor Neuron Disease" were used in combination with the list of Latin American countries from the United Nations. All observational studies were included. A methodological overview was performed using the principles of descriptive epidemiology. Results: Overall, 1364 publications were identified and 36 studies were selected, covering 13 Latin American countries. According to the original reports, ALS occurrence varied among countries with a standardized incidence 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 repeat expansion was reported in Cuba and Brazil. We identified age at onset between 50 and 60 years. 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 a perspective of ALS variability across Latin America and highlights specific differences when comparing to Europe and North America. However, we cannot draw firm conclusions because of different methodological concerns within the studies.

Variation in worldwide incidence of amyotrophic lateral sclerosis: a meta-analysis

Background

To assess the worldwide variation of amyotrophic lateral sclerosis (ALS) incidence, we performed a systematic review and meta-analysis of population-based data published to date.

Methods

We reviewed Medline and Embase up to June 2015 and included all population-based studies of newly diagnosed ALS cases, using multiple sources for case ascertainment. ALS crude and standardized incidence (on age and sex using the US 2010 population) were calculated. Random effect meta-analysis and meta-regression were performed using the subcontinent as the main study level covariate. Sources of heterogeneity related to the characteristics of the study population and the study methodology were investigated.

Results

Among 3216 records, 44 studies were selected, covering 45 geographical areas in 11 sub-continents. A total of 13 146 ALS cases and 825 million person-years of follow-up (PYFU) were co-nsidered. The overall pooled worldwide crude ALS incidence was at 1.75 (1.55–1.96)/100 000 PYFU; 1.68 (1.50–1.85)/100 000 PYFU after standardization. Heterogeneity was identified in ALS standardized incidence between North Europe [1.89 (1.46–2.32)/100 000 PYFU] and East Asia [0.83 (0.42–1.24)/100 000 PYFU, China and Japan P = 0.001] or South Asia [0.73 (0.58–0.89)/100 000/PYFU Iran, P = 0.02]. Conversely, homogeneous rates have been reported in populations from Europe, North America and New Zealand [pooled ALS standardized incidence of 1.81 (1.66-1.97)/100 000 PYFU for those areas].

Conclusion

This review confirms a heterogeneous distribution worldwide of ALS, and sets the scene to sustain a collaborative study involving a wide international consortium to investigate the link between ancestry, environment and ALS incidence.

The Epidemiology of Neuromuscular Diseases

Neuromuscular disorders as a group are linked by anatomy with significant differences in pathogenetic mechanisms, clinical expression, and time course of disease. Each neuromuscular disease is relatively uncommon, yet causes a significant burden of disease socioeconomically. Epidemiologic studies in different global regions have demonstrated certain neuromuscular diseases have increased incidence and prevalence rates over time. Understanding differences in global epidemiologic trends will aid clinical research and policies focused on prevention of disease. There is a critical need to understand the global impact of neuromuscular diseases using metrics currently established for communicable and noncommunicable diseases.