Military Service and Amyotrophic Lateral Sclerosis in a Population-based Cohort

What do you think caused your ALS? An analysis of the CDC national amyotrophic lateral sclerosis patient registry qualitative risk factor data using artificial intelligence and qualitative methodology

OBJECTIVE

Amyotrophic lateral sclerosis (ALS) is an incurable, progressive neurodegenerative disease with a significant health burden and poorly understood etiology. This analysis assessed the narrative responses from 3,061 participants in the Centers for Disease Control and Prevention's National ALS Registry who answered the question, "What do you think caused your ALS?"

METHODS

Data analysis used qualitative methods and artificial intelligence (AI) using natural language processing (NLP), specifically, Bidirectional Encoder Representations from Transformers (BERT) to explore responses regarding participants' perceptions of the cause of their disease.

RESULTS

Both qualitative and AI analysis methods revealed several, often aligned themes, which pointed to perceived causes including genetic, environmental, and military exposures. However, the qualitative analysis revealed detailed themes and subthemes, providing a more comprehensive understanding of participants' perceptions. Although there were areas of alignment between AI and qualitative analysis, AI's broader categories did not capture the nuances discovered using the more traditional, qualitative approach. The qualitative analysis also revealed that the potential causes of ALS were described within narratives that sometimes indicate self-blame and other maladaptive coping mechanisms.

CONCLUSIONS

This analysis highlights the diverse range of factors that individuals with ALS consider as perceived causes for their disease. Understanding these perceptions can help clinicians to better support people living with ALS (PLWALS). The analysis highlights the benefits of using traditional qualitative methods to supplement or improve upon AI-based approaches. This rapidly evolving area of data science has the potential to remove barriers to accessing the rich narratives of people with lived experience.

Prevalence of amyotrophic lateral sclerosis in the United States using established and novel methodologies, 2017

Objective:To estimate the prevalence of amyotrophic lateral sclerosis (ALS) in the United States for 2017 using data from the National ALS Registry (Registry) as well as capture-recapture methodology to account for under-ascertainment. Established in 2010, the Registry collects and examines data on ALS patients in the US to better describe the epidemiology of ALS (i.e. risk factor exposures, demographics).Methods: The Registry compiled data from national administrative databases (from the Centers for Medicare and Medicaid Services, the Veterans Health Administration, and the Veterans Benefits Administration) and a voluntary enrollment data through a web portal (www.cdc.gov/als). To estimate the number of missing cases, capture-recapture methodology was utilized.Results: The Registry conservatively identified 17,800 adult persons (lower-bound estimate) who met the Registry definition of ALS for an age-adjusted prevalence of 5.5 per 100,000 US population. Using capture-recapture methodology, we obtained a "mean case count" of 24,821 ALS cases (prevalence of 7.7 per 100,000 U.S. population) and estimated the upper-bound estimate to be 31,843 cases (prevalence of 9.9 per 100,000 U.S. population). The pattern of patient characteristics (e.g. age, sex, and race/ethnicity) remained unchanged from previous Registry reports. Overall, ALS was most common among whites, males, and persons aged 60-69 years. The age groups with the lowest number of cases were persons aged 18-39 years. Males had a higher prevalence than females overall and across all data sources.Conclusions: Existing Registry methodology, along with capture-recapture methodology, are being used to better describe the epidemiology and demographics of ALS in the US.

Demographics, clinical characteristics, and prognostic factors of amyotrophic lateral sclerosis in Midwest

INTRODUCTION/AIMS

The Midwest has the highest regional prevalence of self-reported amyotrophic lateral sclerosis (ALS) in the United States, but with limited epidemiological studies. We aimed to explore the characteristics of patients with ALS in the Midwest.

METHODS

This was a retrospective cohort study of participants with ALS deceased between January, 2010, and September, 2020, registered with the ALS Association Mid-America Chapter. Demographics and clinical variables included gender, race/ethnicity, military status, site of onset, interventions (gastrostomy, non-invasive ventilation, tracheostomy), and visits to ALS Association-registered clinics. Disease characteristics were compared to the National ALS Registry, and survival analysis was performed followed by sample augmentation with historical data to estimate survival with hypothetical censoring.

RESULTS

The database included 1447 participants with a mean age at diagnosis of 65.7 ± 11.9 y (>60 y at diagnosis: 72%). The median survival from symptom onset was 28.0 mo (95% confidence limit: 26.3, 29.7); sample augmentation increased this to 41.0 mo (38.5, 43.5). Bulbar onset disease and older age at diagnosis were associated with shorter survival. Participants not followed in ALS-Association registered clinics were more frequently male, had familial onset and tracheostomy. Veterans (N = 298) were older at diagnosis but had similar survival after adjustment for age.

DISCUSSIONS

Our cohort had an older age at onset and more frequent bulbar onset than the National ALS Registry, perhaps reflecting ascertainment biases in each registry. Prospective cohort studies with more clinical and functional data are needed to better characterize ALS in Midwest, veterans, and non-clinic populations, and to optimize care.

Military service and related risk factors for amyotrophic lateral sclerosis

BACKGROUND

The cause of amyotrophic lateral sclerosis (ALS) is unknown, but occupations have been explored as a potential proxy measure of risk. There is a substantial body of literature connecting military service to ALS. We aimed to summarize and assess the quality of this evidence.

METHODS

Systematic review of the literature, including observational studies which explored one of the following exposures: general military service (army, air force, marines, or navy); or specific exposures associated with military service measured among military personnel. The outcome of interest was ALS incidence, which could include onset, diagnosis, or death from ALS.

RESULTS

A total of 2642 articles were screened. Following exclusion, 19 articles remained for inclusion in the systematic review, including 1 meta-analysis and 18 original observational studies. Most studies were of moderate quality. In general, the relationship between military service was suggestive of an increased risk, particularly among Gulf War and WWII veterans. Exposure to pesticides (including Agent Orange) certain chemicals (exhaust, burning agents), heavy metals, and head trauma appeared to increase the risk of ALS among military personnel.

CONCLUSIONS

There is a possible association between military service and the subsequent development of ALS; however, the evidence was limited. Studies were generally hindered by small sample sizes and inadequate follow-up time. Future studies should endeavor to objectively measure specific exposures, or combinations thereof, associated with military service, as this will be of vital importance in implementing preventative strategies into military organizations.

Study of Occupational Chromium, Iron, and Nickel Exposure and Amyotrophic Lateral Sclerosis in Denmark

Studies of occupational metal exposures and amyotrophic lateral sclerosis (ALS) have focused primarily on known neurotoxicants, including lead, mercury, selenium, and cadmium. However, these exposures are often co-occurring with other lesser studied metals. We conducted a population-based case-control study with the aim of assessing associations between occupational chromium, iron, and nickel exposures and risk of ALS. We identified ALS cases in Denmark from 1982 through 2013 from the Danish National Patient Registry and matched them to 100 controls based on birth year and sex. Cumulative metal exposures were estimated using job exposure matrices applied to occupational history from the Danish Pension Fund. Although mutually adjusted odds of ALS were higher in men with chromium exposures in the third quartile (aOR = 1.24; 95% CI 0.91, 1.69) and fourth quartile (aOR = 1.19; 95% CI: 0.80, 1.76) compared to those with no exposure, differences did not reach statistical significance. We also observed higher odds of ALS in women with nickel exposures in the third quartile (aOR = 2.21; 95% CI: 1.14, 4.28), but not for the fourth quartile (aOR = 0.61; 95% CI: 0.23, 1.64). Our findings do not suggest associations between occupational exposures to these metals and ALS. However, unavoidable non-differential misclassification from the use of JEMs may have masked truly increased risk.

Chronic Traumatic Encephalopathy and Neuropathological Comorbidities

With age, the presence of multiple neuropathologies in a single individual becomes increasingly common. Given that traumatic brain injury and the repetitive head impacts (RHIs) that occur in contact sports have been associated with the development of many neurodegenerative diseases, including chronic traumatic encephalopathy (CTE), Alzheimer's disease, Lewy body disease, and amyotrophic lateral sclerosis, it is becoming critical to understand the relationship and interactions between these pathologies. In fact, comorbid pathology is common in CTE and likely influenced by both age and the severity and type of exposure to RHI as well as underlying genetic predisposition. Here, we review the major comorbid pathologies seen with CTE and in former contact sports athletes and discuss what is known about the associations between RHI, age, and the development of neuropathologies. In addition, we examine the distinction between CTE and age-related pathology including primary age-related tauopathy and age-related tau astrogliopathy.

Environmental and Occupational Risk Factors of Amyotrophic Lateral Sclerosis: A Population-Based Case-Control Study

Objectives: Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neurodegenerative disease with still unknown etiology. We aimed at investigating the association between environmental and occupational factors with ALS risk. Methods: We performed a population-based case-control study in four Italian provinces (Catania, Modena, Novara, and Reggio Emilia) by administration of tailored questionnaires to ALS cases (n = 95) and randomly selected population referents (n = 135). We estimated ALS risk by calculating the odds ratio (OR) with its 95% confidence interval (CI) using an unconditional logistic regression model. Results: We found a positive association with disease risk for history of occupation in the agricultural sector (OR = 2.09, 95% CI 0.79-7.54), especially for longer than 10 years (OR = 2.72, 95% 1.02-7.20). Overall occupational exposure to solvents also suggested a positive association, especially for thinners (OR = 2.27, 95% CI 1.14-4.54) and paint removers (OR = 2.01, 95% CI 0.90-4.48). Both occupational and environmental exposure to electromagnetic fields show a slightly increased risk with OR = 1.69 (95% CI 0.70-4.09) and 2.41 (95% CI 1.13-5.12), respectively. Occupational but not environmental exposure to pesticides (OR = 1.22, 95% CI 0.63-2.37), particularly fungicides, and exposure to metals (OR = 4.20, 95% CI 1.88-9.38), particularly lead, mercury, and selenium, showed an imprecise but positive association. Finally, there was an indication of increased risk for living in proximity to water bodies. Conclusions: Despite the caution that needs to be used due to some study limitations, such as the low number of exposed subjects and the possibility of recall bias, these results suggest the potential role of some environmental and occupational factors in ALS etiology.

Amyotrophic Lateral Sclerosis Among Veterans Deployed in Support of Post-9/11 U.S. Conflicts

INTRODUCTION

Amyotrophic lateral sclerosis (ALS) is a recognized military service-connected condition. Prior prevalence studies of ALS among U.S. war Veterans were not able to address concerns related to neurodegenerative sequelae of traumatic brain injury (TBI) and disregarded risk heterogeneity from occupational categories within service branches.

MATERIALS AND METHODS

We identified the prevalence of definite and possible ALS and cumulative incidence of definite ALS among Post-9/11 U.S. Veterans deployed in support of Post-9/11 conflicts (mean age 36.3) who received care in the Veterans Health Administration during fiscal years 2002-2015. Using a case-control study design, we also evaluated the association of TBI and major military occupation groups with ALS adjusting for demographics and comorbidities.

RESULTS

The prevalence of ALS was 19.7 per 100,000 over 14 years. Both prevalence and cumulative incidence of definite ALS were significantly higher among Air Force personnel compared to other service branches and among tactical operation officers and health care workers compared to general and administrative officers. Neither TBI nor younger age (<45 years) was associated with ALS. Depression, cardiac disease, cerebrovascular disease, high blood pressure, and obstructive sleep apnea were clinical comorbidities significantly associated with ALS in this population of Veterans.

CONCLUSION

This study among a cohort of relatively young Veterans showed a high ALS prevalence, suggesting an early onset of ALS among deployed military service members. The higher prevalence among some military specific occupations highlights the need to determine which occupational exposures specific to these occupations (particularly, Air Force personnel, tactical operations officers, and health care workers) might be associated with early onset ALS.

High BMI is associated with low ALS risk: A population-based study

OBJECTIVE

To investigate the temporal relationship among prediagnostic body mass index (BMI), weight change, and risk of amyotrophic lateral sclerosis (ALS).

METHODS

From the compulsory Norwegian tuberculosis screening program, we collected objectively measured BMI from 85% of all citizens (near 1.5 million) between 20 and 70 years of age living in 18 of 19 Norwegian counties between 1963 and 1975. For those who participated in later health surveys, we collected further information on weight change, lifestyle, and health. We identified ALS cases until September 2017 through national registries of diagnoses at death and at encounters with the specialist health service. Both Cox hazard models and flexible parametric survival models were fitted to address our research question.

RESULTS

We identified 2,968 ALS cases during a mean of 33 (maximum 54) years follow-up. High prediagnostic BMI was associated with low subsequent ALS risk across the typical ALS ages in both sexes. Overall, hazard ratio (HR) for ALS per 5-unit increase in prediagnostic BMI was 0.83 (95% confidence interval [CI] 0.79-0.88). After an initial increase during the first 10 years, it decreased almost linearly throughout the observation period and was 0.69 (95% CI 0.62-0.77) after 50 years. Those in the quartile with highest weight gain had lower ALS risk than those in the lowest quartile (HR 0.63, 95% CI 0.44-0.89).

CONCLUSION

High BMI and weight gain are associated with low ALS risk several decades later. The strength of the association between BMI and ALS risk increases up to 50 years after BMI measurement.

Heavy Metal Neurotoxicants Induce ALS-Linked TDP-43 Pathology

Heavy metals, such as lead, mercury, and selenium, have been epidemiologically linked with a risk of ALS, but a molecular mechanism proving the connection has not been shown. A screen of putative developmental neurotoxins demonstrated that heavy metals (lead, mercury, and tin) trigger accumulation of TDP-43 into nuclear granules with concomitant loss of diffuse nuclear TDP-43. Lead (Pb) and methyl mercury (MeHg) disrupt the homeostasis of TDP-43 in neurons, resulting in increased levels of transcript and increased splicing activity of TDP-43. TDP-43 homeostasis is tightly regulated, and positively or negatively altering its splicing-suppressive activity has been shown to be deleterious to neurons. These changes are associated with the liquid-liquid phase separation of TDP-43 into nuclear bodies. We show that lead directly facilitates phase separation of TDP-43 in a dose-dependent manner in vitro, possibly explaining the means by which lead treatment results in neuronal nuclear granules. Metal toxicants also triggered the accumulation of insoluble TDP-43 in cultured cells and in the cortices of exposed mice. These results provide novel evidence of a direct mechanistic link between heavy metals, which are a commonly cited environmental risk of ALS, and molecular changes in TDP-43, the primary pathological protein accumulating in ALS.

Chronic Traumatic Encephalopathy Within an Amyotrophic Lateral Sclerosis Brain Bank Cohort

Chronic traumatic encephalopathy (CTE) is a progressive neurodegenerative disorder linked to repetitive head impacts and has been associated with amyotrophic lateral sclerosis (ALS), a fatal, degenerative neuromuscular disorder. The Department of Veterans Affairs Biorepository Brain Bank (VABBB) is a tissue repository that collects antemortem disease progression data and postmortem central nervous system tissue from veterans with ALS. We set out to determine the frequency of co-morbid ALS and CTE in the VABBB cohort and to characterize the clinical, genetic, and pathological distinctions between participants with ALS only and those with both ALS and CTE (ALS+CTE). Of 155 participants, 9 (5.8%) had neuropathologically confirmed ALS+CTE. Participants with ALS+CTE were more likely to have a history of traumatic brain injury (p < 0.001), served during the first Persian Gulf War (p < 0.05), and to have more severe tau pathology within the frontal cortex and spinal cord (p < 0.05). The most common exposures to head impacts included contact sports (n = 5) and military service (n = 2). Clinically, participants with ALS+CTE were more likely to have bulbar onset ALS (p = 0.006), behavioral changes (p = 0.002), and/or mood changes (p < 0.001). Overall, compared with ALS in isolation, comorbid ALS+CTE is associated with a history of TBI and has a distinct clinical and pathological presentation.

An Evidence Map of the Women Veterans' Health Research Literature (2008-2015)

BACKGROUND

Women comprise a growing proportion of Veterans seeking care at Veterans Affairs (VA) healthcare facilities. VA initiatives have accelerated changes in services for female Veterans, yet the corresponding literature has not been systematically reviewed since 2008. In 2015, VA Women's Health Services and the VA Women's Health Research Network requested an updated literature review to facilitate policy and research planning.

METHODS

The Minneapolis VA Evidence-based Synthesis Program performed a systematic search of research related to female Veterans' health published from 2008 through 2015. We extracted study characteristics including healthcare topic, design, sample size and proportion female, research setting, and funding source. We created an evidence map by organizing and presenting results within and across healthcare topics, and describing patterns, strengths, and gaps.

RESULTS

We identified 2276 abstracts and assessed each for relevance. We excluded 1092 abstracts and reviewed 1184 full-text articles; 750 were excluded. Of 440 included articles, 208 (47%) were related to mental health, particularly post-traumatic stress disorder (71 articles), military sexual trauma (37 articles), and substance abuse (20 articles). The number of articles addressing VA priority topic areas increased over time, including reproductive health, healthcare organization and delivery, access and utilization, and post-deployment health. Three or fewer articles addressed each of the common chronic diseases: diabetes, hypertension, depression, or anxiety. Nearly 400 articles (90%) used an observational design. Eight articles (2%) described randomized trials.

CONCLUSIONS

Our evidence map summarizes patterns, progress, and growth in the female Veterans' health and healthcare literature. Observational studies in mental health make up the majority of research. A focus on primary care delivery over clinical topics in primary care and a lack of sex-specific results for studies that include men and women have contributed to research gaps in addressing common chronic diseases. Interventional research using randomized trials is needed.

Military service and the risk of amyotrophic lateral sclerosis: A meta-analysis

To explore the relationship between the risk of amyotrophic lateral sclerosis and exposure to overall military service, we conducted a search of articles relevant to military service and the risk of ALS that used human subjects and were published in English through 20 May 2016, using Ovid Medline and Embase databases. Studies specially investigating the risk of ALS for Gulf war veterans were excluded. Quality of the cohort and case-control studies was assessed according to the Newcastle-Ottawa Scale (NOS). Analysis of data and publication bias were performed with Review Manager 5.3. A total of 8 case-control studies and 3 cohort studies were included in the meta-analysis. Only two case-control studies were conducted in Japan, comparing to 9 studies conducted in Europe/USA. The NOS scores of all studies were ≥6/9. The risk of ALS was significantly increased in military personnel compared to non-military personnel (pooled OR=1.29, 95% CI: 1.08-1.54, by random-effects model), with a moderate heterogeneity (P=0.01, I²=55%) due to some studies with lower quality, conformed by subgroup and sensitivity analysis. The present meta-analysis supports a positive association between overall military service and the risk of ALS. Additional studies are needed to find out related factors influencing the ALS risk of veterans, especially by gender and for specific geographic regions such as Asia. That would also do some favor to explore the etiology and mechanism of ALS.

The Potential Role of BMAA in Neurodegeneration

Neurodegenerative diseases are a major public health issue throughout the world with devastating effects on patients and families. Sporadic forms of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis are generally thought to develop as a consequence of genetic susceptibility and environmental influences. A number of environmental triggers have been identified in association with amyotrophic lateral sclerosis and Parkinson's disease. We discuss the role of β-methylamino-L-alanine in the development of neurodegeneration and the potential importance of this neurotoxin as a risk for neurodegeneration.

Occupational formaldehyde and amyotrophic lateral sclerosis

Prior studies have yielded inconsistent evidence regarding the association between formaldehyde exposure and amyotrophic lateral sclerosis (ALS). We conducted a population case-control study in the Danish National Registries on the relationship between occupationally-derived formaldehyde exposure and ALS. Occupational history was obtained from a comprehensive and prospectively recorded pension database of all paid work in Denmark since 1964, and was linked to a job-exposure matrix to derive individual exposure estimates. Each case was matched to 4 age- and sex-matched population controls alive on the date of the case diagnosis via risk set sampling, and odds ratios and confidence intervals (CI) were calculated via conditional logistic regression, adjusting for potential confounders. There were 3650 incident cases of ALS in the Danish National Patient Register from 1982 to 2009. Among controls, 25% were ever employed in jobs with a positive prevalence of formaldehyde exposure. Exposure to formaldehyde was associated with a 1.3-fold increased rate of ALS (95% CI 1.2-1.4). This study suggests that formaldehyde exposure, or employment in formaldehyde-exposed occupations, is related to the risk of ALS.

Environmental and Occupational Exposures and Amyotrophic Lateral Sclerosis in New England

BACKGROUND

Recent data provide support for the concept that potentially modifiable exposures are responsible for sporadic amyotrophic lateral sclerosis (ALS).

OBJECTIVE

To evaluate environmental and occupational exposures as risk factors for sporadic ALS.

METHODS

We performed a case-control study of ALS among residents of New England, USA. The analysis compared questionnaire responses from 295 patients with a confirmed ALS diagnosis to those of 225 controls without neurodegenerative illness.

RESULTS

Self-reported job- or hobby-related exposure to one or more chemicals, such as pesticides, solvents, or heavy metals, increased the risk of ALS (adjusted OR 2.51; 95% CI 1.64-3.89). Industries with a higher toxicant exposure potential (construction, manufacturing, mechanical, military, or painting) were associated with an elevated occupational risk (adjusted OR 3.95; 95% CI 2.04-8.30). We also identified increases in the risk of ALS associated with frequent participation in water sports, particularly waterskiing (adjusted OR 3.89; 95% CI 1.97-8.44). Occupation and waterskiing both retained independent statistical significance in a composite model containing age, gender, and smoking status.

CONCLUSIONS

Our study contributes to a growing body of literature implicating occupational- and hobby-related toxicant exposures in ALS etiology. These epidemiologic study results also provide motivation for future evaluation of water-body-related risk factors.

Amyotrophic Lateral Sclerosis and the Military: A Population-based Study in the Danish Registries

BACKGROUND

Prior studies have suggested that military service may be associated with the development of amyotrophic lateral sclerosis (ALS). We conducted a population-based case-control study in Denmark to assess whether occupation in the Danish military is associated with an increased risk of developing ALS.

METHODS

There were 3,650 incident cases of ALS recorded in the Danish National Patient Registry between 1982 and 2009. Each case was matched to 100 age- and sex-matched population controls alive and free of ALS on the date of the case diagnosis. Comprehensive occupational history was obtained from the Danish Pension Fund database, which began in 1964.

RESULTS

2.4% (n = 8,922) of controls had a history of employment in the military before the index date. Military employees overall had an elevated rate of ALS (odds ratio [OR] = 1.3; 95% confidence interval [CI]: 1.1, 1.6). A 10-year increase in years employed by the military was associated with an OR of 1.2 (95% CI: 1.0, 1.4), and all quartiles of time employed were elevated. There was little suggestion of a pattern across calendar year of first employment, but there was some evidence that increasing age at first employment was associated with increased ALS rates. Rates were highest in the decade immediately following the end of employment (OR = 1.6; 95% CI: 1.2, 2.2).

CONCLUSIONS

In this large population-based case-control study, employment by the military is associated with increased rates of ALS. These findings are consistent with earlier findings that military service or employment may entail exposure to risk factors for ALS.

Race/ethnicity, socioeconomic status, and ALS mortality in the United States

OBJECTIVE

To determine whether race/ethnicity and socioeconomic status are associated with amyotrophic lateral sclerosis (ALS) mortality in the United States.

METHODS

The National Longitudinal Mortality Study (NLMS), a United States-representative, multistage sample, collected race/ethnicity and socioeconomic data prospectively. Mortality information was obtained by matching NLMS records to the National Death Index (1979-2011). More than 2 million persons (n = 1,145,368 women, n = 1,011,172 men) were included, with 33,024,881 person-years of follow-up (1,299 ALS deaths , response rate 96%). Race/ethnicity was by self-report in 4 categories. Hazard ratios (HRs) for ALS mortality were calculated for race/ethnicity and socioeconomic status separately and in mutually adjusted models.

RESULTS

Minority vs white race/ethnicity predicted lower ALS mortality in models adjusted for socioeconomic status, type of health insurance, and birthplace (non-Hispanic black, HR 0.61, 95% confidence interval [CI] 0.48-0.78; Hispanic, HR 0.64, 95% CI 0.46-0.88; other races, non-Hispanic, HR 0.52, 95% CI 0.31-0.86). Higher educational attainment compared with < high school was in general associated with higher rate of ALS (high school, HR 1.23, 95% CI 1.07-1.42; some college, HR 1.24, 95% CI 1.04-1.48; college, HR 1.10, 95% CI 0.90-1.36; postgraduate, HR 1.31, 95% CI 1.06-1.62). Income, household poverty, and home ownership were not associated with ALS after adjustment for race/ethnicity. Rates did not differ by sex.

CONCLUSION

Higher rate of ALS among whites vs non-Hispanic blacks, Hispanics, and non-Hispanic other races was not accounted for by multiple measures of socioeconomic status, birthplace, or type of health insurance. Higher rate of ALS among whites likely reflects actual higher risk of ALS rather than ascertainment bias or effects of socioeconomic status on ALS risk.

Prevalence of Amyotrophic Lateral Sclerosis - United States, 2012-2013

PROBLEM/CONDITION

Amyotrophic lateral sclerosis (ALS), commonly known as Lou Gehrig's disease, is a progressive and fatal neuromuscular disease for which no cure or viable treatment has been identified. ALS, like most noncommunicable diseases, is not a nationally notifiable disease in the United States. The prevalence of ALS in the United States during 2010-2011 was estimated to be 3.9 cases per 100,000 persons in the general population. Updated prevalence estimates are needed to help monitor disease status, better understand etiology, and identify risk factors for ALS.

PERIOD COVERED

2012-2013.

DESCRIPTION OF SYSTEM

The National ALS Registry, established in 2009, collects data on ALS patients in the United States to better describe the incidence and prevalence of ALS, examine risk factors such as environmental and occupational exposures, and characterize the demographics of those living with ALS. To identify prevalent cases of ALS, data are compiled from four national administrative databases (maintained by the Centers for Medicare and Medicaid Services, the Veterans Health Administration, and the Veterans Benefits Administration). To identify cases not included in these databases and to better understand risk-factors associated with ALS and disease progression, the Registry also includes data that are collected from patients who voluntarily enroll and complete online surveys.

RESULTS

During 2012 and 2013, the Registry identified 14,713 and 15,908 persons, respectively, who met the surveillance case definition of ALS. The estimated ALS prevalence rate was 4.7 cases per 100,000 U.S. population for 2012 and 5.0 per 100,000 for 2013. Due to revisions to the algorithm and use of death data from the National Death Index, an updated prevalence estimate has been calculated retrospectively for October 19, 2010-December 31, 2011. This updated estimate showed a prevalence rate of 4.3 per 100,000 population and a total of 13,282 cases. Since the inception of the Registry, the pattern of characteristics (e.g., age, sex, and race/ethnicity) among persons with ALS have remained unchanged. Overall, ALS was more common among whites, males, and persons aged 60-69 years. The age groups with the lowest number of ALS cases were persons aged 18-39 years and those aged ≥80 years. Males had a higher prevalence rate of ALS than females overall and across all data sources. These findings remained consistent during October 2010-December 2013.

INTERPRETATION

The Registry is the only available data source that can be used to estimate the national prevalence for ALS in the United States. Use of both administrative national databases and self-report from patients enables a comprehensive approach to estimate ALS prevalence. The overall increase in the prevalence rate from 4.3 per 100,000 persons (revised) during 2010-2011 to 4.7 and 5.0 per 100,000 persons, respectively, during 2012-2013 likely is not an actual increase in the number of ALS cases. Rather, this increase might be attributed to improved case ascertainment due to the refinement of the algorithm used to identify definite ALS cases, along with an increased public awareness of the Registry. Registry estimates of ALS prevalence are consistent with findings from long-established ALS registries in Europe and from smaller-scale epidemiologic studies previously conducted in the United States.

PUBLIC HEALTH ACTIONS

Data collected by the National ALS Registry are being used to better describe the epidemiology of ALS in the United States and to help facilitate research. The combined approach of using national administrative databases and a self-enrollment web portal to collect data is novel and potentially could be used for other non-notifiable diseases such as Parkinson's disease or multiple sclerosis. Increased public awareness of the Registry might lead to more ALS cases being identified from the secure web portal (https://www.cdc.gov/als), which can ascertain cases apart from the national administrative databases. For example, in 2014, the ALS Ice Bucket Challenge, a social media-centered campaign, received extensive public visibility and created increased awareness of ALS. The Agency for Toxic Substances and Disease Registry (ATSDR) works closely with ALS advocacy and support groups, researchers, health care professionals, and others to promote the National ALS Registry and to identify all cases of ALS in the United States. In addition to estimating the prevalence of ALS, the Registry is being used to collect specimens from patient enrollees through a new biorepository, connect patient enrollees with new clinical trials and epidemiologic studies, and fund studies to help learn more about the etiology of ALS. Additional information about the National ALS Registry is available at http://www.cdc.gov/als or by calling toll-free at 1-877-442-9719.

Military service, deployments, and exposures in relation to amyotrophic lateral sclerosis etiology

BACKGROUND

Factors underlying a possible excess of amyotrophic lateral sclerosis (ALS) among military veterans remain unidentified. Limitations of previous studies on this topic include reliance on ALS mortality as a surrogate for ALS incidence, low statistical power, and sparse information on military-related factors.

OBJECTIVES

We evaluated associations between military-related factors and ALS using data from a case-control study of U.S. military veterans.

METHODS

From 2005 to 2010, we identified medical record-confirmed ALS cases via the National Registry of Veterans with ALS and controls via the Veterans Benefits Administration's Beneficiary Identification and Records Locator System database. In total, we enrolled 621 cases and 958 frequency-matched controls in the Genes and Environmental Exposures in Veterans with Amyotrophic Lateral Sclerosis study. We collected information on military service and deployments and 39 related exposures. We used unconditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). We used inverse probability weighting to adjust for potential bias from confounding, missing covariate data, and selection arising from a case group that disproportionately included long-term survivors and a control group that may or may not differ from U.S. military veterans at large.

RESULTS

The odds of ALS did not differ for veterans of the Air Force, Army, Marines, and Navy. We found higher odds of ALS for veterans whose longest deployment was World War II or the Korean War and a positive trend with total years of all deployments (OR=1.27; 95% CI: 1.06, 1.52). ALS was positively associated with exposure to herbicides for military purposes, nasopharyngeal radium, personal pesticides, exhaust from heaters or generators, high-intensity radar waves, contaminated food, explosions within one mile, herbicides in the field, mixing and application of burning agents, burning agents in the field, and Agent Orange in the field, with ORs between 1.50 and 7.75.

CONCLUSIONS

Although our results need confirmation, they are potentially important given the large number of U.S. military veterans, and they provide clues to potential factors underlying the apparent increase of ALS in veteran populations.

Participation in Physical Activity and Risk for Amyotrophic Lateral Sclerosis Mortality Among Postmenopausal Women

IMPORTANCE

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal disease with no known cause. Case studies primarily of athletes and several case-control studies have suggested that high levels of strenuous physical activity (PA) may increase the risk for ALS. This relationship has yet to be evaluated among women in population-based cohort studies.

OBJECTIVE

To evaluate the relationship between PA and risk for ALS mortality in a large cohort of postmenopausal women.

DESIGN, SETTING, AND PARTICIPANTS

The Women's Health Initiative (WHI) enrolled 161 809 postmenopausal women, aged 50 to 79 years (mean [SD] age, 63.6 [7.24] years), between 1993 and 1998 into either a clinical trial or an observational study at 40 clinical research centers across the United States. We conducted a cohort study from November 2014 to September 2015 using baseline and mortality data during an average of 9.6 years of follow-up from the entire WHI cohort, through September 1, 2013 (with 1.1% lost to follow-up), to address whether there is a relationship between PA and ALS mortality.

EXPOSURES

The WHI assessed frequency and duration of mild, moderate, and strenuous PA at baseline via self-administered questionnaire.

MAIN OUTCOMES AND MEASURES

Underlying cause of death from ALS collected from death certificates.

RESULTS

The WHI enrolled 161 809 women, of whom 165 died of ALS; women who died of ALS were older (median age, 66 years; interquartile range, 61-69 years) compared with the total WHI study population (median age, 63 years; interquartile range, 57-69 years). Age-adjusted ALS mortality rates varied from 7.4 (95% CI, 5.5-9.9)/100 000 person-years for no strenuous PA to 10.6 (95% CI, 5.6-20.0)/100 000 person-years for strenuous PA 3 or more days per week (P = .07). Adjusted for age and body mass index (calculated as weight in kilograms divided by height in meters squared), the odds ratio for death from ALS for participants with strenuous PA 3 or more days per week compared with no reported strenuous PA was 1.56 (95% CI, 1.02-2.37; P = .04).

CONCLUSIONS AND RELEVANCE

To our knowledge, this is the first cohort study to report an increased risk for ALS mortality associated with strenuous PA in postmenopausal women. The association between strenuous PA and ALS risk observed does not compromise the overall benefit of strenuous PA for total mortality, coronary heart disease, and breast cancer reported in other WHI investigations, but it may provide an important clue to the etiology of ALS, if replicated by other studies.