Amyotrophic lateral sclerosis in Sardinia, insular Italy, 1995-2009

Incidence of amyotrophic lateral sclerosis before and during the COVID-19 pandemic: evidence from an 8-year population-based study in Central Italy based on healthcare utilization databases

BACKGROUND

Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disorder with a high multidimensional burden, with an obscure etiopathogenesis.

METHODS

We designed a longitudinal, population-based study of people residing in Central Italy (Marche Region) who were beneficiaries of the National Health System. People with an unprecedented ALS hospitalization (335.20 ICD-9 CM) or tagged with an ALS exemption between 2014 and 2021 were considered incident cases. ALS cases residing in the region for <3 years or with an active ALS exemption or hospitalized for ALS before 2014 were excluded. We used secondary sources to identify new ALS diagnoses. The regional referral center for ALS's database was used to test the accuracy of secondary sources in detecting cases. ALS mean incidence was compared to that reported in similar studies conducted in Italy. The incidence rate trend adjusted by sex and age was evaluated using the Poisson regression model.

RESULTS

We detected 425 new ALS cases (median age: 70y) in the 2014-2021 period, with a mean incidence of 3.5:100,000 py (95%CI: 3.2-3.8; M:F = 1.2), similar to that reported in similar studies conducted in Italy. No trend was observed during 2014-2019. After including 2020-2021 in the model, we observed a mean decrease in incidence of 5.8% (95% CI 2.0%; 9.5%, p = 0.003).

CONCLUSION

We show a decrease in the incidence rate of ALS in Marche, during the 2014-2021 period, as a possible outcome of a delayed neurological assessment and diagnosis during the pandemic. An ad hoc developed identification algorithm, based on healthcare utilization databases, is a valuable tool to assess the health impact of global contingencies.

LAENALS: epidemiological and clinical features of amyotrophic lateral sclerosis in Latin America

OBJECTIVE

The Latin American Epidemiologic study of ALS (LAENALS) aims to gather data on ALS epidemiology, phenotype, and risk factors in Cuba, Chile, and Uruguay, to understand the impact of genetic and environmental factors on ALS.

METHODS

A harmonized data collection protocol was generated, and a Latin-American Spanish language Register was constructed. Patient data were collected in Uruguay in 2018, in Chile from 2017 to 2019, and in Cuba between 2017 and 2018. Statistical analysis was performed using SPSS 25.0.0 software. Crude cumulative incidence, standardized incidence, and prevalence were calculated in the population aged 15 years and older.

RESULTS

During 2017-2019, 90 people with ALS from Uruguay (55.6% men), 219 from Chile (54.6% men), and 49 from Cuba (55.1% men) were included. The cumulative crude incidence in 2018 was 1.73/100,000 persons in Uruguay, 1.08 in Chile and 0.195 in Cuba. Crude prevalence in 2018 was 2.19 per 100,000 persons in Uruguay, 1.39 in Chile and 0.55 in Cuba. Mean age at onset was 61.8 ± 11.96 SD years in Uruguay, 61.9 ± 10.4 SD years in Chile, and 60.21 ± 12.45 SD years in Cuba (p = 0.75). Median survival from onset was 32.43 months (21.93 - 42.36) in Uruguay, 24 months (13.5 - 33.5) in Chile, and 29 months (15 - 42.5) in Cuba (p = 0.006).

CONCLUSIONS

These preliminary data from LAENALS confirm the lower incidence and prevalence of ALS in counties with admixed populations. The LAENALS database is now open to other Latin American countries for harmonized prospective data collection.

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.

Demographic changes in a large motor neuron disease cohort in Portugal: a 27 year experience

Objective: Motor Neuron Diseases (MND) have a large clinical spectrum, being the most common amyotrophic lateral sclerosis (ALS) but there is significant clinical heterogeneity. Our goal was to investigate this heterogeneity and any potential changes during a long period. Methods: We performed a retrospective cohort study among a large Portuguese cohort of MND patients (n = 1550) and investigated changing patterns in clinical and demographic characteristics over the 27-year period of our database. With that aim, patients were divided into three 9-year groups according to the date of their first visit to our unit: P1, 1994-2002; P2, 2003-2011; P3, 2012-2020. Results: The overall cohort's clinical and demographic characteristics are consistent with clinical experience, but our findings point to gradual changes over time. Time pattern analysis revealed statistically significant differences in the distribution of clinical phenotypes, the average age of onset, diagnostic delay, the proportin of patients using respiratory support with noninvasive ventilation (NIV), time to NIV, and survival. Across time, in the overall cohort, we found an increasing age at onset (p = 0.029), a decrease of two months in diagnostic delay (p < 0.001) and a higher relative frequency of progressive muscular atrophy patients. For ALS patients with spinal onset, from P1 to P2, there was a more widespread (54.8% vs 69.4%, p = 0.005) and earlier (36.9 vs 27.2 months, p = 0.05) use of NIV and a noteworthy 13-month increase in median survival (p = 0.041). Conclusions: Our results probably reflect better comprehensive care, and they are relevant for future studies exploring the impact of new treatments on ALS patients.

Epidemiology of amyotrophic lateral sclerosis in the north east Tuscany in the 2018–2021 period

Background

The incidence of Amyotrophic Lateral Sclerosis (ALS) varies among different geographical areas and seems to increase over time. This study aimed to examine the epidemiologic data of ALS in the north-east Tuscany and compare the results with those of similar surveys.

Methods

Data from ALS cases diagnosed in Florence and Prato Hospitals were prospectively collected from 1st June 2018 to 31st May 2021.

Results

The age- and sex-adjusted incidence rate of ALS in cases per 100,000 population was 2.71 (M/F ratio: 1.21), significantly higher as compared to that reported in the 1967-1976 decade in the same geographical area (0.714). The age- and sex-adjusted incidence rate among resident strangers was similar to that of the general population (2.69). A slightly higher incidence rate (4.36) was observed in the north-east area of Florence province, which includes the Mugello valley. The mean prevalence was of 7.17/100,00. The mean age at diagnosis was 69.7 years, with a peak between 70 and 79 years among men and a smoother age curve among women.

Conclusions

ALS epidemiological features in north-east Tuscany are in line with other Italian and European Centers. The dramatic increase of the local disease burden over the last decades probably reflects better ascertainment methods and health system.

Increasing prevalence 2015-2019 of amyotrophic lateral sclerosis in Sardinia, Italy

BACKGROUND

While amyotrophic lateral sclerosis (ALS) incidence has increased during the last decades, structured evidence on increased prevalence is lacking. After reporting a significant yearly increase of ALS incidence over a 10-year period, we checked for increased prevalence in Southern Sardinia over a quinquennium.

METHODS

ALS patients (El Escorial Criteria) recruited from the study area and followed at ALS Centre, University of Cagliari, were included. Prevalence was computed for January 1, 2015 and January 1, 2019 and was calculated for the overall ALS population as well as for tracheostomized and non-tracheostomized patients.

RESULTS

We observed a non-significant trend for greater ALS prevalence in 2019 than in 2015 (18.31 per 100,000 vs. 15.26 per 100,000; rate ratio: 1.83, p = 0.01). By contrast, a significantly raising 2015 to 2019 ALS prevalence was observed in tracheostomized patients. No significant difference could be detected in non-tracheostomized.

CONCLUSIONS

We provided the highest prevalence rate to date reported in the worldwide literature, and also showed a non-significant raising ALS prevalence in the Sardinian population over a quinquennium. The trend in raising ALS prevalence was likely due to extended survival due to invasive interventions.

Genetic landscape of ALS in Malta based on a quinquennial analysis

Genetic risk for amyotrophic lateral sclerosis (ALS) is highly elevated in genetic isolates, like the island population of Malta in the south of Europe, providing a unique opportunity to investigate the genetics of this disease. Here we characterize the clinical phenotype and genetic profile of the largest series of Maltese ALS patients to date identified throughout a 5-year window. Cases and controls underwent neuromuscular assessment and analysis of rare variants in ALS causative or risk genes following whole-genome sequencing. Potentially damaging variants or repeat expansions were identified in more than 45% of all patients. The most commonly affected genes were ALS2, DAO, SETX and SPG11, an infrequent cause of ALS in Europeans. We also confirmed a significant association between ATXN1 intermediate repeats and increased disease risk. Damaging variants in major ALS genes C9orf72, SOD1, TARDBP and FUS were however either absent or rare in Maltese ALS patients. Overall, our study underscores a population that is an outlier within Europe and one that represents a high percentage of genetically explained cases.

Incidence of amyotrophic lateral sclerosis in Sardinia, Italy: age-sex interaction and spatial-temporal variability

Objective: This study assessed amyotrophic lateral sclerosis (ALS) incidence in Sardinia, Italy, and the combined contribution of age and gender to disease risk. We also checked disease incidence for spatial-temporal variability. Methods: ALS patients from all neurological centers of the study area who had onset during 2010-2019 and fulfilled El Escorial revised diagnostic criteria were included. Incidence was calculated for the overall study area and each province separately. Additive interaction between age and sex on ALS incidence was assessed. Results: The average crude annual incidence rate was 3.6/100,000 person-years (95% CI, 3.2-4.1), 3.1/100,000 person-years (95% CI, 2.7-3.5) when age-adjusted. Incidence was greater among people aged ≥65 years and men, with the two variables undergoing significant additive interaction. Incidence increased yearly over the study period, with annual incidence correlating with the increasing yearly frequency of people aged ≥65 years, but not with the proportion of incident cases carrying genetic mutations. Stratifying by province, the rates from Oristano and South Sardinia were higher than the rate from Cagliari. ALS patients from areas at different risk were comparable for frequency of clinical/genetic features. Conclusion: ALS incidence in Sardinia was in the upper part of the European range of variability. We also provided new information about age and sex as risk factors for ALS, showing male sex as a modifier of the effect of aging on ALS incidence. Spatial-temporal variations in ALS incidence correlated to changes in the proportion of the aging population rather than to the distribution of genetic factors.

Prevalence of amyotrophic lateral sclerosis in Latium region, Italy

OBJECTIVE

Prevalence estimate of amyotrophic lateral sclerosis (ALS) ranged between 1.1/100,000 and 11.2/100,000 inhabitants with different design of the study (prospective or retrospective) and sample size. The aim of this study is to conduct for the first time an estimate of the ALS prevalence in the Latium region.

MATERIALS AND METHODS

The study was performed in Latium, a region located in the center of Italy, with a population, as of January 1, 2016, of 5888.472 inhabitants. In this region, a network of 15 clinical centers (of which 4 referral ALS centers are located in Rome) and 10 local health authorities involved in the diagnosis and treatment of ALS patients has been identified. Each patient was classified according to the El Escorial revised criteria.

RESULTS

The prevalence study in 2016 identified 353 ALS cases (200 males). By considering population aged >=20 years, the total crude prevalence rate resulted 7.33 (CI95% 6.59-8.14) × 100,000 and 8.75 and 6.05 in males and females, respectively. Age-specific prevalence rates did not differ among males and females in the population aged less than 49 years. The difference emerged in population aged > 50 years. This type of diagnosis was recorded for 343 patients (11 missing). 68% of these patients have a definite diagnosis, 14% likely, 11% possible, and 12% defined as suspect.

CONCLUSIONS

The estimate of prevalence rates observed in this study is probably in line with the values reported in the literature for prospective prevalence studies.

Trends in survival of ALS from a population-based registry

Objective: To assess survival of ALS patients in general and in selected demographic and clinical subgroups comparing two periods (1998-2000 vs. 2008-2010). Methods: Newly diagnosed adults resident of Lombardy, Northern Italy from a population-based registry were included. Data were collected on age at diagnosis, sex, site of onset, diagnostic delay, and El-Escorial diagnostic category. Patients were followed until death or last observation. Survival was evaluated using Kaplan-Meier curves and Cox's proportional hazards models. Results: In 2008-2010 (267 patients), median survival was 2.4 years and 1-year, 2-year, 3-year and 5-year survival rates were 79%, 56%, 41% and 24%. Longer survival was associated with male sex, younger age, spinal onset, and longer diagnostic delay. Multivariable analysis confirmed higher death in 65-69yr (HR 2.8; 95% CI 1.4-5.6), 70-74yr (HR 3.2; 95% CI 1.6-6.3) and 75 + yr (HR 6.9; 95% CI 3.5-13.8) categories, compared to ≤49yr, in females (HR 1.4; 95% CI 1.02-1.8), compared to males, and in patients diagnosed after 6-12 months (HR 1.9; 95% CI 1.4-2.7), compared with longer diagnostic delay. In 1998-2000 (235 patients), median survival was 2.2 years. The 1-year, 2-year, 3-year and 5-year survival rates were 77%, 53%, 38% and 20%. When adjusting for demographic and clinical variables, the HR for death in 2008-2010 versus 1998-2000 was 0.80 (95% CI 0.66-0.98). A significant increase of survival in 2008-2010 was found only in patients aged 50-59yr and 70-74yr at diagnosis. Conclusions: Survival of ALS has increased over time in the last decades, especially in middle aged and elderly patients. The benefits of comprehensive care in selected age groups might explain our findings.

ALS incidence and population aging in Northern Italy

Objective: Data on and increase of the incidence of amyotrophic lateral sclerosis (ALS) are conflicting and reflect the use of differing populations and designs. We investigated the incidence of ALS using data from a large population-based registry (SLALOM) in two three-year periods using the same diagnostic criteria and equal methods of case ascertainment. Methods: The registry is based in Lombardy, a 10 million population area of Northern Italy. Using different sources of cases (hospital discharge and ambulatory records, regional claims and prescription records) from nine Lombardy provinces (population, 5,485,163), all patients with newly diagnosed ALS during the periods 1998-2000 and 2008-2010 were included. Results: A total of 235 and 440 newly diagnosed patients were traced during the two study periods. The corresponding incidence rates were, respectively, 1.61 and 2.72 per 100,000 person-years. Data varied with age, sex and province by a significant increase was found only in men aged 65 through 74 years. Conclusions: Based on our findings, the increased incidence of ALS with time is real and can be largely interpreted as a reflection of the advancing age of the general population.

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.

Neuropathological profile of long-duration amyotrophic lateral sclerosis in military Veterans

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting both the upper and lower motor neurons. Although ALS typically leads to death within 3 to 5 years after initial symptom onset, approximately 10% of patients with ALS live more than 10 years after symptom onset. We set out to determine similarities and differences in clinical presentation and neuropathology in persons with ALS with long vs. those with standard duration. Participants were United States military Veterans with a pathologically confirmed diagnosis of ALS (n = 179), dichotomized into standard duration (<10 years) and long-duration (≥10 years). The ALS Functional Rating Scale-Revised (ALSFRS-R) was administered at study entry and semi-annually thereafter until death. Microglial density was determined in a subset of participants. long-duration ALS occurred in 76 participants (42%) with a mean disease duration of 16.3 years (min/max = 10.1/42.2). Participants with long-duration ALS were younger at disease onset (P = 0.002), had a slower initial ALS symptom progression on the ALSFRS-R (P < 0.001) and took longer to diagnose (P < 0.002) than standard duration ALS. Pathologically, long-duration ALS was associated with less frequent TDP-43 pathology (P < 0.001). Upper motor neuron degeneration was similar; however, long-duration ALS participants had less severe lower motor neuron degeneration at death (P < 0.001). In addition, the density of microglia was decreased in the corticospinal tract (P = 0.017) and spinal cord anterior horn (P = 0.009) in long-duration ALS. Notably, many neuropathological markers of ALS were similar between the standard and long-duration groups and there was no difference in the frequency of known ALS genetic mutations. These findings suggest that the lower motor neuron system is relatively spared in long-duration ALS and that pathological progression is likely slowed by as yet unknown genetic and environmental modifiers.

Rapid Eye Movement Sleep Behavior Disorder and Neurodegenerative Diseases: An Update

Rapid eye movement sleep behavior disorder (RBD) is a sleep behavior disorder characterized by abnormal behaviors and loss of muscle atonia during rapid eye movement (REM) sleep. RBD is generally considered to be associated with synucleinopathies, such as Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), and usually precedes years before the first symptom of these diseases. It is believed that RBD predicts the neurodegeneration in synucleinopathy. However, increasing evidences have shown that RBD is also found in non-synucleinopathy neurodegenerative diseases, including Alzheimer’s disease (AD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS), etc. Sleep disturbance such as RBD may be an early sign of neurodegeneration in these diseases, and also serve as an assessment of cognitive impairments. In this review, we updated the clinical characteristics, diagnosis, and possible mechanisms of RBD in neurogenerative diseases. A better understanding of RBD in these neurogenerative diseases will provide biomarkers and novel therapeutics for the early diagnosis and treatment of the diseases.

Muscleblind acts as a modifier of FUS toxicity by modulating stress granule dynamics and SMN localization

Mutations in fused in sarcoma (FUS) lead to amyotrophic lateral sclerosis (ALS) with varying ages of onset, progression and severity. This suggests that unknown genetic factors contribute to disease pathogenesis. Here we show the identification of muscleblind as a novel modifier of FUS-mediated neurodegeneration in vivo. Muscleblind regulates cytoplasmic mislocalization of mutant FUS and subsequent accumulation in stress granules, dendritic morphology and toxicity in mammalian neuronal and human iPSC-derived neurons. Interestingly, genetic modulation of endogenous muscleblind was sufficient to restore survival motor neuron (SMN) protein localization in neurons expressing pathogenic mutations in FUS, suggesting a potential mode of suppression of FUS toxicity. Upregulation of SMN suppressed FUS toxicity in Drosophila and primary cortical neurons, indicating a link between FUS and SMN. Our data provide in vivo evidence that muscleblind is a dominant modifier of FUS-mediated neurodegeneration by regulating FUS-mediated ALS pathogenesis.

Predictors of diagnostic delay in amyotrophic lateral sclerosis: a cohort study based on administrative and electronic medical records data

Objectives: To characterize the timing and pathway of amyotrophic lateral sclerosis (ALS) diagnosis and to identify predictors of delayed diagnosis in a retrospective cohort. Methods: The cohort included all patients with incident ALS between 2010 and 2014 in Friuli-Venezia Giulia (FVG) region, Italy, admitted to two University Hospitals. Information on demographics, clinical presentation, and healthcare use was obtained from health databases and electronic medical records (EMRs). Total diagnostic time (TDT), the interval between ALS symptoms onset and diagnosis, was compared between patient groups through Wilcoxon-Mann-Whitney test. The adjusted odds ratio (aOR), with 95% confidence interval (95% CI), of having a TDT ≥12 months was estimated using unconditional logistic regression. Results: Among 134 patients, median TDT (interquartile range [IQR]) was 11.5 months (7.1-18.3), shorter in those aged <60 years vs. ≥60 years (8.1; 5.1-11.1 vs. 12.4; 7.4-21.5; p = 0.0064), first referred to a neurologist vs. other specialist (10.2; 6.1-16.3 vs. 13.2; 8.1-24.5; p = 0.0386) and without neurologic comorbidities (11.1; 7.1-16.5 vs. 19.7; 8.8-33.7; p = 0.0243). TDT was ≥12 months in 64 (48.5%) patients and was predicted by male sex (aOR: 2.47; 95% CI: 1.06-5.75), age at onset ≥60 years (11.46; 3.13-41.9), spinal onset (2.04; 1.00-5.93), and prior therapies or first referral to a non-neurologist (3.15; 1.36-7.29). Conclusions: In this cohort, delayed diagnosis was common, particularly in older patients and in those with neurological comorbidities. Timely referral to a neurologist may improve diagnostic timing.

Epidemiology of amyotrophic lateral sclerosis in Friuli-Venezia Giulia, North-Eastern Italy, 2002-2014: a retrospective population-based study

OBJECTIVES

To describe the epidemiology of Amyotrophic Lateral Sclerosis (ALS) in Friuli-Venezia Giulia (FVG) region, Italy, over a 13-year period (2002-2014), estimating ALS (a) incidence, prevalence, and clinical features; (b) mortality, also comparing Udine municipality to the rest of FVG.

METHODS

We conducted a retrospective population-based study. ALS incident cases were ascertained using multiple sources and validated through expert review. We calculated crude and standardized incidence rate (IR), point prevalence and mortality rate (MR), each with 95% confidence interval. Standardized incidence (SIR) and mortality (SMR) ratio were calculated to compare Udine to FVG.

RESULTS

Among 444 incident cases (50.0% men, median age 68.5 years), onset was bulbar in 30.2%, spinal in 59.9%, mixed in 9.9%; 3.6% had familial ALS. Crude and 2000 European population standardized IR was respectively 2.81 (2.56-3.09) and 2.09 (1.89-2.29) per 100,000 person-years. Standardized male-to-female incidence ratio was 1.05. IR peaked at age 65-74 years (men: 9.93, 8.04-12.32; women: 7.74, 6.18-9.67) and decreased thereafter. Prevalence was 8.36 (6.74-9.97) cases per 100,000 inhabitants on 30 June 2009 and 7.98 (6.40-9.56) on 30 June 2014. SIR was 1.20 and SMR 1.11.

CONCLUSIONS

When assessed over a long period, incidence of ALS was in the range of Italian and European population-based registries and showed a consistent pattern by age and sex. IR and MR were only slightly higher in Udine vs. FVG.

Potential Role of the Gut Microbiome in ALS: A Systematic Review

Amyotrophic lateral sclerosis (ALS) etiology and pathophysiology are not well understood. Recent data suggest that dysbiosis of gut microbiota may contribute to ALS etiology and progression. This review aims to explore evidence of associations between gut microbiota and ALS etiology and pathophysiology. Databases were searched for publications relevant to the gut microbiome in ALS. Three publications provided primary evidence of changes in microbiome profiles in ALS. An ALS mouse model revealed damaged tight junction structure and increased permeability in the intestine versus controls along with a shifted microbiome profile, including decreased levels of butyrate-producing bacteria. In a subsequent publication, again using an ALS mouse model, researchers showed that dietary supplementation with butyrate relieved symptoms and lengthened both time to onset of weight loss and survival time. In a small study of ALS patients and healthy controls, investigators also found decreased levels of butyrate-producing bacteria. Essential for maintaining gut barrier integrity, butyrate is the preferred energy source of intestinal epithelial cells. Ten other articles were reviews and commentaries providing indirect support for a role of gut microbiota in ALS pathophysiology. Thus, these studies provide a modicum of evidence implicating gut microbiota in ALS disease, although more research is needed to confirm the connection and determine pathophysiologic mechanisms. Nurses caring for these patients need to understand the gut microbiome and its potential role in ALS in order to effectively counsel patients and their families about emerging therapies (e.g., prebiotics, probiotics, and fecal microbial transplant) and their off-label uses.

Age-specific ALS incidence: a dose-response meta-analysis

To evaluate the association between worldwide ALS incidence rates and age, using a dose-response meta-analysis. We reviewed Medline and Embase up to July 2016 and included all population-based studies of newly-diagnosed cases, using multiple sources for case ascertainment. A dose-response meta-analysis was performed. A meta-regression investigated potential sources of heterogeneity. Of 3254 articles identified in the literature, we included 41 incidence studies covering 42 geographical areas. Overall, the fit between observed and predicted age-specific rates was very good. The expected variation of ALS incidence with age was characterized, in each study, by a progressive increase in the incidence from the 40s leading to a peak in the 60s or 70s, followed by a sharp decrease. Cochran's Q test suggested a significant heterogeneity between studies. Overall, estimated patterns of ALS age-specific incidence (at which the peak was reached) were similar among subcontinents of Europe and North America: peak of ALS incidence ranged in these areas between 6.98 and 8.17/100,000 PYFU, which referred to age in the range 71.6-77.4 years. The relationship between age and ALS incidence appeared different for Eastern Asia which was characterized by a peak of ALS incidence at 2.20/100,000 PYFU around 75 years of age. This study confirms the consistency of the age-specific ALS incidence pattern within different subcontinents. Age-specific incidence appears lower in Eastern Asia as compared to Europe and North America.

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.

Assessing amyotrophic lateral sclerosis prevalence in Norway from 2009 to 2015 from compulsory nationwide health registers

OBJECTIVE

In Norway, diagnoses from specialist health care visits, drug prescriptions, and causes of deaths are registered in compulsory health registers. We aimed to determine amyotrophic lateral sclerosis (ALS) prevalence from 2009 to 2015 by combining these registers.

METHODS

We validated the Norwegian Patient Registry (NPR) through hospital files, and linked it with the Norwegian Cause of Death Registry and the Norwegian Prescription Database. Poisson regression models were fitted for estimating gender ratios, time trends and possible interactions. Similar models were used for mortality data subtracted from the dataset.

RESULTS

Eleven percent of patients with at least one ALS-related entry in NPR did not have ALS. ALS prevalence could nevertheless be reliably estimated through ascertaining cases identified in two separate registers, or with at least two entries in NPR with first entry within four years prior to prevalence date. ALS prevalence remained stable, and was 7.6/100,000 (95% CI 6.9-8.4) at 31st December 2015. Mean male:female ratio was higher for prevalence (1.8; 95% CI 1.6-2.0) than for mortality (1.5; 95% CI 1.2-1.8) (p = 0.04). There were also significant regional differences in prevalence (p < 0.01) but not in mortality.

CONCLUSIONS

Norwegian compulsory health registers provide reliable tools for ALS surveillance, and suggest gender and regional differences in survival after diagnosis.

The changing picture of amyotrophic lateral sclerosis: lessons from European registers

Prospective population based-registers of amyotrophic lateral sclerosis (ALS) have operated in Europe for over two decades, and have provided important insights into our understanding of ALS. Here, we review the benefits that population registers have brought to the understanding of the incidence, prevalence, phenotype and genetics of ALS and outline the core operating principles that underlie these registers and facilitate international collaboration. Going forward, we offer lessons learned from our collective experience of operating population-based ALS registers in Europe for over two decades, focusing on register design, maintenance, identification and management of bias and the value of cross-national harmonisation and integration.

Factors predicting survival in ALS: a multicenter Italian study

The aim of this multicenter, retrospective study is to investigate the role of clinical characteristics and therapeutic intervention on ALS prognosis. The study included patients diagnosed from January 1, 2009 to December 31, 2013 in 13 Italian referral centers for ALS located in 10 Italian regions. Caring neurologists collected a detailed phenotypic profile and follow-up data until death into an electronic database. One center collected also data from a population-based registry for ALS. 2648 incident cases were collected. The median survival time from onset to death/tracheostomy was 44 months (SE 1.18, CI 42-46). According to univariate analysis, factors related to survival from onset to death/tracheostomy were: age at onset, diagnostic delay, site of onset, phenotype, degree of certainty at diagnosis according to revised El Escorial criteria (R-EEC), presence/absence of dementia, BMI at diagnosis, patients' provenance. In the multivariate analysis, age at onset, diagnostic delay, phenotypes but not site of onset, presence/absence of dementia, BMI, riluzole use, R-EEC criteria were independent prognostic factors of survival in ALS. We compared patients from an ALS Registry with patients from tertiary centers; the latter ones were younger, less frequently bulbar, but more frequently familial and definite at diagnosis. Our large, multicenter study demonstrated the role of some clinical and demographic factors on ALS survival, and showed some interesting differences between referral centers' patients and the general ALS population. These results can be helpful for clinical practice, in clinical trial design and to validate new tools to predict disease progression.

Isolated rapid eye movement sleep without atonia in amyotrophic lateral sclerosis

OBJECTIVE

The aim of this study was to quantitatively analyze, with the most recent and advanced tools, the presence of periodic leg movements during sleep (PLMS) and/or rapid eye movement (REM) sleep without atonia (RSWA), in a group of patients with amyotrophic lateral sclerosis (ALS), and to assess their eventual correlation with the clinical severity of the disease.

METHODS

Twenty-nine ALS patients were enrolled (mean age 63.6 years) along with 28 age-matched "normal" controls (mean age 63.8 years). Functional impairment due to ALS was evaluated using the ALS-Functional Rating Scale-Revised (ALS-FRS) and the ALS severity scale (ALSSS). Full video polysomnographic night recordings were obtained, and PLMS were analyzed by considering their number/hour of sleep and periodicity index, the distribution of intermovement intervals, and the distribution during the night. The characteristics of the chin electromyogram (EMG) amplitude during REM sleep were analyzed by means of the automatic atonia index and the number of chin EMG activations (movements).

RESULTS

The ALS patients showed longer sleep latency than the controls, together with an increase in number of stage shifts, increased sleep stage 1, and decreased sleep stage 2. None of the leg PLMS parameters were different between the ALS patients and controls. The REM atonia index was significantly decreased in the ALS patients, and the number of chin movements/hour tended to increase. Both REM atonia index and number of chin movements/hour correlated significantly with the ALS-FRS; REM atonia was higher and chin movements were less in ALS patients with more preserved function (higher scores on the ALS-FRS).

CONCLUSION

Abnormal REM sleep atonia seemed to be a genuine effect of ALS pathology per se and correlated with the clinical severity of the disease. It is unclear if this might constitute the basis of a possible risk for the development of REM sleep behavior disorder or represent a form of isolated RSWA in ALS.

Five-Year Incidence of Amyotrophic Lateral Sclerosis in British Columbia (2010-2015)

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal degenerative neurological disease with significant effects on quality of life. International studies continue to provide consistent incidence values, though complete case ascertainment remains a challenge. The Canadian population has been understudied, and there are currently no quantitative data on the incidence of ALS in British Columbia (BC). The objectives of this study were to determine the five-year incidence rates of ALS in BC and to characterize the demographic patterns of the disease.

METHODS

The capture-recapture method was employed to estimate ALS incidence over a five-year period (2010-2015). Two sources were used to identify ALS cases: one database from an ALS medical centre and another from a not-for-profit ALS organization.

RESULTS

During this time period, there were 690 incident cases within the two sources. The capture-recapture method estimated 57 unobserved cases, corresponding to a crude five-year incidence rate of 3.29 cases per 100,000 (CI 95%=3.05-3.53). The mean age of diagnosis was 64.6 (CI 95%=59.7-69.4), with 63.5 (CI 95%=56.9-70.1) for men and 65.7 (CI 95%=58.6-72.7) for women. There was a slight male preponderance in incidence, with a 1.05:1 ratio to females. Peak numbers in incidence occurred between the ages of 70 and 79.

CONCLUSIONS

The incidence of ALS in BC was found to be consistent with international findings though nominally higher than that in other Canadian provinces to date.

Prognostic factors and survival of ALS patients from Belgrade, Serbia

Our aim was to assess the incidence, survival and its prognostic factors in ALS patients from the area of the City of Belgrade, Serbia. A retrospective analysis included 325 probable or definite ALS cases from all five Belgrade neurology departments in the period 1992-2009. Each patient was regularly followed up during the disease until death or until 31 December 2009. Results showed that the average annual ALS incidence rate was 1.11 per 100,000 inhabitants. Male predominance was registered, except for patients with ALS onset after the age of 80 years. Mean survival from the first symptoms was 4.4 ± 0.2 years. Cumulative probability of survival was 71% for two years, 24% for five years, and 17% for seven years. Patients with diagnostic delay longer than 1.6 years had a 1.4-times better chance for survival (p <0.01). Spinal-onset patients on riluzole therapy had 1.8-times better survival (p < 0.01). Patients with early-onset ALS and higher ALSFRS-R score at initial evaluation also had somewhat better survival (p < 0.05). In conclusion, the average annual ALS incidence rate was 1.11 per 100,000 inhabitants. Longer survival was observed in patients with early onset, longer diagnostic delay, less functional impairment at the time of diagnosis, and riluzole treatment.

Black hairy tongue in a patient with amyotrophic lateral sclerosis

Black hairy tongue (BHT) is a condition characterized by the elongation of filiform papillae associated with a marked discoloration, from yellowish-brown to black, and a thick lingual coating. BHT is usually observed in the elderly and in patients with limited self-sufficiency, as a consequence of poor oral hygiene. In this perspective, the patients affected by amyotrophic lateral sclerosis (ALS) represent a high-risk category for the occurrence of BHT. The fast and inexorable loss of their self-sufficiency due to progressive muscle atrophy as well as the impropriate education of healthcare assistants have demonstrated to have significant reflection on the maintenance of an adequate standard of oral hygiene. This paper firstly described a case of BHT in a patient affected by ALS. A case of BHT in a patient (Caucasic, male, 63 years old) affected by ALS was described. The primary goal of the work was to teach and motivate the patient to the use of the tongue cleaner in association with the local application of chlorexidine 0.20%. Furthermore, in order to support the patient with accurate domiciliary oral hygiene, a proper training for his health-care assistant was provided. The maintenance of the oral health of ALS patient is fundamental to prevent systemic complications that could jeopardize the already fragile physical balance of these patients. The dedicated monitoring by a dentist or a dental hygienist would seem essential in order to achieve this objective.

Epidemiology of amyotrophic lateral sclerosis: A review of literature

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of motor neurons, resulting in worsening weakness of voluntary muscles until death occurs from respiratory failure. The incidence of ALS in European populations is two to three people per year per 100,000 of the general population. In Europe, crude prevalences range from 1.1/100,000 population in Yugoslavia to 8.2/100,000 in the Faroe Islands. Major advances have been made in our understanding of the genetic causes of ALS, whereas the contribution of environmental factors has been more difficult to assess and large-scale studies have not yet revealed a replicable, definitive environmental risk factor. The only established risk factors to date are older age, male gender and a family history of ALS. Median survival time from onset to death is usually 3 years from the first appearance of symptoms. Older age and bulbar onset are consistently reported to have poorer outcomes. However, there are conflicting data regarding gender, diagnostic delay and El Escorial criteria. The rate of symptom progression has been revealed to be an independent prognostic factor. Psychosocial factors and impaired cognitive function are negatively related to ALS outcome, while nutritional status and respiratory function are also related to ALS prognosis. The effect of enteral nutrition on survival is still unclear, although noninvasive positive pressure ventilation (NIPPV) has been found to improve survival. These findings have relevant implications for the design of future trials.

Stratification of ALS patients' survival: a population-based study

The natural history of amyotrophic lateral sclerosis (ALS) and patient risk stratification are areas of considerable research interest. We aimed (1) to describe the survival of a representative cohort of French ALS patients, and (2) to identify covariates associated with various patterns of survival using a risk classification analysis. ALS patients recruited in the FRALim register (2000-2013) were included. Time-to-death analyses were performed using Kaplan-Meier method and Cox model. A recursive partitioning and amalgamation (RECPAM) algorithm analysis identified subgroups of patients with different patterns of survival. Among 322 patients, median survival times were 26.2 and 15.6 months from time of onset and of diagnosis, respectively. Four groups of patients were identified, depending on their baseline characteristics and survival (1) ALSFRS-R slope >0.46/month and definite or probable ALS (median survival time (MST) 10.6 months); (2) ALSFRS-R slope >0.46/month and possible or probable laboratory-supported ALS (MST: 18.1 months); (3) ALSFRS-R slope ≤0.46/month and definite or probable ALS (MST: 22.5 months), and (4) ALSFRS-R slope ≤0.46/month and possible or probable laboratory-supported ALS (MST: 37.6 months). Median survival time is among the shortest ever reported by a worldwide population-based study. This is probably related to the age structure of the patients (the oldest identified to date), driven by the underlying population (30 % of subjects older than 60 years). Further research in the field of risk stratification could help physicians better anticipate prognosis of ALS patients, and help improve the design of randomized controlled trials.

Space-time distribution of the ALS incident cases by onset type in the Health District of Ferrara, Italy

OBJECTIVES

An ecological study in the resident population of the Health District (HD) of Ferrara, Italy, has been carried out to establish the distribution in space and time of the amyotrophic lateral sclerosis (ALS) incident cases according to the disease onset type and gender in the period 1964-2009.

MATERIAL AND METHODS

The hypothesis of a uniform distribution was assumed.

RESULTS

The incident cases of spinal onset ALS and bulbar onset ALS were evenly distributed in space and time in both men and women. The spinal onset ALS incident cases distribution according to gender was significantly different from the expected in the extra-urban population (20 observed cases in men 95% Poisson confidence interval 12.22-30.89, expected cases in men 12.19; six observed cases in women 95% Poisson confidence interval 2.20-13.06, expected cases in women 13.81), whereas no difference was found in the urban population. The spinal onset ALS incidence was higher in men than in women in the extra-urban population (difference between the rates = 1.53, 95% CI associated with the difference 0.52-2.54), whereas no difference between sexes was found in the urban population.

CONCLUSIONS

The uneven distribution according to gender of the spinal onset ALS incident cases only in the extra-urban population suggests the involvement of a gender related environmental risk factor associated with the extra-urban environment. Despite some limits of the spatial analysis in the study of rare diseases, the results appear consistent with the literature data.

Constructional apraxia in frontotemporal dementia associated with the C9orf72 mutation: broadening the clinical and neuropsychological phenotype

In our study we analysed clinical and neuropsychological data in a cohort of 57 Sardinian patients with FTD (55 apparently unrelated and two belonging to the same family), who underwent genetic screening for the C9orf72 mutation. Eight out of 56 patients were found positive for the C9orf72 mutation representing 14% of the entire cohort and 31.6% of the familial cases (6/19). C9orf72 mutated patients differed from the other FTD cases of the cohort for a younger age of onset, higher frequency of familial history for FTD and higher prevalence of delusional psychotic symptoms and hallucinations. In the neuropsychological assessment, C9orf72 mutated patients differed from non-mutated for the high frequency of visuospatial dysfunction regarding constructional apraxia (p = 0.02). In conclusion, our study confirms that Sardinian FTD patients have peculiar genetic characteristics and that C9orf72 mutated patients have a distinctive clinical and neuropsychological profile that could help differentiate them from other FTD patients. In our cohort we found that constructional apraxia, rarely reported in FTD, can properly discriminate between C9orf72 mutated and non-mutated patients and contribute to broaden the neuropsychological profile in frontotemporal dementia associated with this mutation.

A fruitful endeavor: modeling ALS in the fruit fly

For over a century Drosophila melanogaster, commonly known as the fruit fly, has been instrumental in genetics research and disease modeling. In more recent years, it has been a powerful tool for modeling and studying neurodegenerative diseases, including the devastating and fatal amyotrophic lateral sclerosis (ALS). The success of this model organism in ALS research comes from the availability of tools to manipulate gene/protein expression in a number of desired cell-types, and the subsequent recapitulation of cellular and molecular phenotypic features of the disease. Several Drosophila models have now been developed for studying the roles of ALS-associated genes in disease pathogenesis that allowed us to understand the molecular pathways that lead to motor neuron degeneration in ALS patients. Our primary goal in this review is to highlight the lessons we have learned using Drosophila models pertaining to ALS research. This article is part of a Special Issue entitled ALS complex pathogenesis.

Genetic architecture of ALS in Sardinia

Conserved populations, such as Sardinians, displaying elevated rates of familial or sporadic amyotrophic lateral sclerosis (ALS) provide unique information on the genetics of the disease. Our aim was to describe the genetic profile of a consecutive series of ALS patients of Sardinian ancestry. All ALS patients of Sardinian ancestry, identified between 2008 and 2013 through the Italian ALS Genetic Consortium, were eligible to be included in the study. Patients and controls underwent the analysis of TARDBP, C9ORF72, SOD1, and FUS genes. Genetic mutations were identified in 155 out of 375 Sardinian ALS cases (41.3%), more commonly the p.A382T and p.G295S mutations of TARDBP and the GGGGCC hexanucleotide repeat expansion of C9ORF72. One patient had both p.G295S and p.A382T mutations of TARDBP and 8 carried both the heterozygous p.A382T mutation of TARDBP and a repeat expansion of C9ORF72. Patients carrying the p.A382T and the p.G295S mutations of TARDBP and the C9ORF72 repeat expansion shared distinct haplotypes across these loci. Patients with cooccurrence of C9ORF72 and TARDBP p.A382T missense mutation had a significantly lower age at onset and shorter survival. More than 40% of all cases on the island of Sardinia carry a mutation of an ALS-related gene, representing the highest percentage of ALS cases genetically explained outside of Scandinavia. Clinical phenotypes associated with different genetic mutations show some distinctive characteristics, but the heterogeneity between and among families carrying the same mutations implies that ALS manifestation is influenced by other genetic and nongenetic factors.

Epidemiology of amyotrophic lateral sclerosis in Emilia Romagna Region (Italy): A population based study

Our objective was to describe incidence and clinical features of ALS from a prospective population-based study in Emilia Romagna Region (ERR). From 2009 onwards, a prospective registry recorded all incident cases of ALS among residents in the ERR (population, 4.4 million inhabitants), involving 17 neurological departments. For each patient, detailed demographic and clinical information was collected by caring physicians. Results showed that from 1 January 2009 to 31 December 2011, 347 patients received a new diagnosis of ALS with a crude incidence rate of 2.63/100,000/year. There was micro-geographic heterogeneity throughout ERR, with higher incidence rates in the low density population (3.27/100,000) (p < 0.01). ALS patients have been more frequently employed in agriculture than the general ERR population (8.64% vs. 4.6%, p < 0.01). Clinical features were similar to those described in previous population based studies. In conclusion, we report incidence rates similar to those reported by European registries, reflecting good accuracy of our prospective study. We confirmed previous studies reporting higher incidence rates in rural areas and among agricultural workers. Although genetics has been gaining increasing importance in ALS aetiology, some epidemiological data are still unexplained. Identifying geographical areas or populations with high incidence rates can be a starting point for identifying environmental risk factors. Further studies having this specific aim can shed light on these topics.

The epidemiology of ALS: a conspiracy of genes, environment and time

Amyotrophic lateral sclerosis (ALS) is a relentlessly progressive neurodegenerative disease of motor neurons, resulting in worsening weakness of voluntary muscles until death from respiratory failure occurs after about 3 years. Although great advances have been made in our understanding of the genetic causes of ALS, the contribution of environmental factors has been more difficult to assess. Large-scale studies of the clinical patterns of ALS, individual histories preceding the onset of ALS, and the rates of ALS in different populations and groups have led to improved patient care, but have not yet revealed a replicable, definitive environmental risk factor. In this Review, we outline what is currently known of the environmental and genetic epidemiology of ALS, describe the current state of the art with respect to the different types of ALS, and explore whether ALS should be considered a single disease or a syndrome. We examine the relationship between genetic and environmental risk factors, and propose a disease model in which ALS is considered to be the result of environmental risks and time acting on a pre-existing genetic load, followed by an automatic, self-perpetuating decline to death.

Global epidemiology of amyotrophic lateral sclerosis: a systematic review of the published literature

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is relatively rare, yet the economic and social burden is substantial. Having accurate incidence and prevalence estimates would facilitate efficient allocation of healthcare resources.

OBJECTIVE

To provide a comprehensive and critical review of the epidemiological literature on ALS.

METHODS

MEDLINE and EMBASE (1995-2011) databases of population-based studies on ALS incidence and prevalence reporting quantitative data were analyzed. Data extracted included study location and time, design and data sources, case ascertainment methods and incidence and/or prevalence rates. Medians and interquartile ranges (IQRs) were calculated, and ALS case estimates were derived using 2010 population estimates.

RESULTS

In all, 37 articles met the inclusion criteria. In Europe, the median incidence rate (/100,000 population) was 2.08 (IQR 1.47-2.43), corresponding to an estimated 15,355 (10,852-17,938) cases. Median prevalence (/100,000 population) was 5.40 (IQR 4.06-7.89), or 39,863 (29,971-58,244) prevalent cases.

CONCLUSIONS

Disparity in rates among ALS incidence and prevalence studies may be due to differences in study design or true variations in population demographics such as age and geography, including environmental factors and genetic predisposition. Additional large-scale studies that use standardized case ascertainment methods are needed to more accurately assess the true global burden of ALS.