Sclerosis In Sweden Research Articles

Incidence rate and prevalence of pediatric-onset multiple sclerosis in Sweden: A population-based register study.

Pediatric-onset multiple sclerosis (PoMS) is associated with high health care use. To plan resource allocation for this patient group, knowledge of the incidence rate and prevalence is important. However, such studies are scarce, few are population-based, and the methodology varies widely. We aimed to address this knowledge gap by performing a nationwide study of the incidence rate and prevalence of PoMS in Sweden, an area of high multiple sclerosis (MS) incidence and prevalence. MS cases were identified by linking two nationwide registers, the National Patient Register and the Swedish MS Registry. MS cases having their first central nervous system demyelinating event or MS clinical onset before age 18 years were classified as pediatric onset. Incidence rate and prevalence were estimated annually over the study period (2006-2016) for the total population and stratified by sex and age group (<12, 12-15, and 16-17 years). Temporal trends and ratios between sexes and age groups were estimated. We identified 238 incident cases from 2006 to 2016, corresponding to an overall crude incidence rate of 1.12 per 100,000 person-years and an overall crude prevalence of 2.82 per 100,000 population. There was a higher incidence rate among females and the highest age category. The overall incidence rate and prevalence estimates remained stable during the study period. Sweden exhibits a consistently high incidence rate and prevalence of PoMS that has remained stable over time. This knowledge serves as a tool to aid in planning resource allocation and health services for this patient population.

Recent trends in disease-modifying therapy use and associated sickness absence and disability pension among people with multiple sclerosis in Sweden

Background: Disease-modifying therapies (DMTs) have led to improved health and work productivity among people with multiple sclerosis (PwMS). Objectives: To describe trajectories of recent DMT use and their association with sickness absence and/or disability pension (SADP) among PwMS in Sweden. Methods: A longitudinal register–based study was conducted among 1395 PwMS with treatment start in 2014/2015. While DMT use over 5 years was assessed using sequence analysis resulting in four clusters, a 7-year (Y−2 toY4) trend of SADP was analyzed using zero-inflated negative binomial regression. Results: Four clusters of DMT use trajectories were identified: long-term non-high-efficacy (483, 34.6%), long-term high-efficacy (572, 41%), escalation (221, 15.8%), and discontinuation (119, 8.5%). Progressive MS and higher expanded disability status scale scores were associated with the escalation, long-term high-efficacy, or discontinuation clusters. PwMS in the long-term high-efficacy and escalation clusters had higher likelihood of being on SADP. However, PwMS initiating high-efficacy DMTs demonstrated steeper decline in SADP than others. Conclusion: Using sequence analysis, this study showed recent DMT use trajectories among PwMS where initiation of high-efficacy DMTs has become more common. The trend of SADP was stable and lower in those using non-high-efficacy DMTs and larger improvements were shown in those initiating high-efficacy DMTs.

Haematopoietic stem cell transplantation for treatment of relapsing-remitting multiple sclerosis in Sweden: an observational cohort study

BackgroundA growing evidence base supports the use of autologous haematopoietic stem cell transplantation (aHSCT) for treatment of relapsing-remitting multiple sclerosis (RRMS), but it has not yet been integrated into most...

The evolution of epilepsy surgery in tuberous sclerosis in Sweden: A national registry study

PurposeThis study aimed to characterize the Swedish cohort of surgically treated patients with TSC and explore differences in preoperative investigation and outcome over time. MethodsData on patient and seizure characteristics were retrieved from the Swedish National Epilepsy Surgery Register. Two-year follow-up results were compared between the years 1997–2010 and 2011–2018. Preoperative investigations were re-evaluated. ResultsEighteen tuberectomies and seven callosotomies were identified. Seizure freedom after tuberectomy was achieved in 11 % (1/9) 1997–2010 and 56 % (5/9) 2011–2018. The number of tuberectomies increased each decade. Patients operated on in 1997–2010 had higher seizure frequency (median 175 seizures/month vs. 102) and incidence of infantile spasms (4/9 vs. 1/9, none after 2011). There was a trend towards surgery at a younger age (median 86 months 1997–2010 vs. 48 months 2011–2018). None with >200 seizure/month, SEGA, or history of infantile spasms achieved seizure freedom. Two patients underwent anterior callosotomy (1992 and 1994) and became free of drop attacks. Five callosotomies were performed between 2011 and 2013, one patient became free of drop attacks. Two complications with new neurological deficits were reported. The median age at surgery was higher in the callosotomy group (14 years) than in the tuberectomy group (5 years). ConclusionSeizure freedom after tuberectomy in patients with TSC has increased over time in our cohort. Signs of a heavier disease burden were more frequently observed 1997–2010 and associated with worse outcomes. Callosotomy operations were prevalent at the beginning of the 2010s.

Self-reported restrictions in different life domains and associated factors among people with multiple sclerosis in Sweden.

The heterogeneous symptoms of multiple sclerosis (MS) can considerably impact the lives of people with MS (PwMS). The aim of this study was to describe the extent of restrictions in different life domains that PwMS experience in relation to their symptoms and level of disability. A cross-sectional survey was conducted among working-age PwMS in Sweden. The 4052 participants who answered the questions on restrictions in work and private life domains (family, leisure activities, and contact with friends/acquaintances) were included. Predictors of restrictions in the four domains were determined through multinomial logistic regression. Approximately one-third of the PwMS reported no restrictions in the domains of work (35.7%), family (38.7%), leisure activities (31.1%) or contact with friends/acquaintances (40.3%), the remaining participants reported moderate to severe restrictions. Tiredness/fatigue was the most commonly reported most-limiting symptom (49.5%). PwMS with Expanded Disability Status Scale (EDSS) scores of zero reported restrictions in life domains ranging from 39.6% (friends/acquaintances) to 45.7% (leisure activities). Age, sex, education, type of living area, MS type, type of most-limiting symptom, and EDSS score predicted restrictions in work and private life domains. Most PwMS reported similar levels of restrictions in both their work and private lives. Restrictions in these life domains were also reported by PwMS with low disability levels (EDSS = 0) and were often associated with invisible symptoms such as fatigue. Even in a contemporary MS cohort, close to 90% of PwMS report limitations due to MS.

Observed associations between indicators of socioeconomic status and risk of multiple sclerosis in Sweden are explained by a few lifestyle-related factors.

The association between socioeconomic status (SES) and the risk of multiple sclerosis (MS) is unclear. The aim was to study whether a potential association between indicators of SES and MS risk in Sweden is explained by lifestyle/environmental factors. Using the Swedish MS registry and the Swedish patient registries, a register study was performed comprising all cases diagnosed with MS in Sweden between 1990 and 2018 (N= 24,729) and five randomly selected controls per case, matched by year and age at disease onset, sex and residential area at disease onset. Data from two matched case-control studies combined comprising data on environment/lifestyle factors (7193 cases, 9609 controls, inclusion period 2005-2018) were also utilized. For all participants, information regarding ancestry, formal education (available 1990-2018) and family income (available 1998-2018) was retrieved from the National Board of Health and Welfare. The registry study revealed no association between education and MS risk, whereas an income exceeding the upper quartile was associated with lower MS risk compared to having an income in the lowest quartile (odds ratio 0.86, 95% confidence interval 0.82-0.90). These findings were replicated in the crude analyses of the case-control study. However, after adjustment for confounding, no association was observed between income and risk of MS. Education and income were not associated with occurrence of MS after adjustment for a few lifestyle-related factors (smoking, alcohol consumption, body mass index and sun exposure habits), indicating that SES has no influence on MS risk besides its association with these lifestyle factors in the Swedish context.

Trajectories of disease-modifying therapies and associated sickness absence and disability pension among 1923 people with multiple sclerosis in Sweden

There is limited information on the trajectories of disease-modifying therapy (DMT) use and their association with sickness absence and/or disability pension (SADP) among people with multiple sclerosis (PwMS). The objective of the study was to identify trajectories of DMT use over 10 years among PwMS, identify sociodemographic and clinical factors associated with the trajectories, and to assess the association between identified trajectories and SADP days. A longitudinal register-based study was conducted, on a prospective data set linked across six nationwide registers, assessing treatment courses of PwMS with DMTs for the 10 years following multiple sclerosis (MS) onset. The study included 1923 PwMS with MS onset in 2007-2010, when aged 19-56 years. In each 6-month-period, their treatment was categorized as before treatment, high-efficacy, non-high-efficacy, or no DMT. Sequence analysis was performed to identify sequences of the treatment categories and cluster them into different DMT trajectories. Cluster belonging, in relation to demographic and clinical characteristics, was assessed through log-multinomial regression analysis. The association of trajectories/cluster-belonging with SADP net days was assessed using generalized estimating equation (GEE) models. Cluster analyses identified 4 trajectories of DMT use: long-term non-high-efficacy DMTs (38.6%), escalation to high-efficacy DMTs (31.2%), delayed start and escalation to high-efficacy DMTs (15.4%), and discontinued/ no DMT (14.2%). Age, MS type, expanded disability status scale (EDSS) score and the number of DMT switches were associated with cluster belonging. The youngest age group (18-25) were more likely to be in the escalation to high-efficacy cluster. People with primary progressive MS were more likely to be in the delayed start or discontinued/ no DMT cluster. Higher EDSS scores were associated to being in the other three clusters than in the long-term non-high-efficacy DMTs cluster. Higher number of DMT switches were associated with being in the escalation to high-efficacy DMTs cluster but less likely to be in the delayed start or discontinued/ no DMT clusters. Descriptive analyses showed a trend of fewer mean SADP days among PwMS using non-high-efficacy DMT than the other clusters about 9 years after onset. PwMS in the escalation to high-efficacy and discontinued/no DMT clusters had more SADP days. PwMS in the delayed start and escalation to high-efficacy DMTs cluster, started with fewer SADP days which increased over time. SADP days adjusted through GEE models showed trends comparable with the descriptive analysis. This study described the long-term real-world trajectories of DMT use among PwMS in Sweden using sequence analysis and showed the association of the trajectories with SADP days as well as sociodemographic and clinical characteristics.

RWD105 Healthcare Resource Utilization and Disease Modifying Treatment Use Among Patients with Multiple Sclerosis in Sweden: A Nationwide Register-Based Study

RWD105 Healthcare Resource Utilization and Disease Modifying Treatment Use Among Patients with Multiple Sclerosis in Sweden: A Nationwide Register-Based Study

Incidence and prevalence of systemic sclerosis in Sweden, 2004–2015, a register-based study

Objectiveswe aim to present an in-depth report of the incidence and prevalence of systemic sclerosis (SSc) in Sweden in a nation-wide register-based study covering the entire Swedish population Methodseach individual residing in Sweden is given a unique personal identity number. We linked the National Patient Register and the Total Population Register to identify 1) patients with prevalent SSc on 2015–12–31 and 2) patients with incident SSc during the time period 2004–2015 based on ICD-10 codes. We estimated prevalence and incidence overall and stratified on age, sex, and county. Resultswe identified 1774 prevalent cases, median age was 65 years (IQR 19.2) and 84% were women. The point prevalence estimate was 22.7 per 100,000 (95%CI 13.3–32.0). 1139 individuals were newly diagnosed with SSc during 2004–2015 with a median age of 60 years (IQR 20.6) and 80% were women. The mean standardized incidence was 11.9 per 1,000,000 person-years (95%CI 5.1–18.7). The annual incidence remained stable over the study period. Women had five times higher incidence and prevalence than men. The highest prevalence stratified by age strata was observed in the group aged 70–79. ConclusionSSc incidence and prevalence in Sweden are comparable to estimates from southern Europe, as opposed to the previous assumption of lower occurrence in northern Europe. We further observe that SSc incidence has been rather constant throughout recent years in Sweden with no obvious increase.

Rituximab Infusion Timing, Cumulative Dose, and Hospitalization for COVID-19 in Persons With Multiple Sclerosis in Sweden

Rituximab Infusion Timing, Cumulative Dose, and Hospitalization for COVID-19 in Persons With Multiple Sclerosis in Sweden

Modeling the cost-effectiveness of prolonged-release fampridine for the treatment of walking impairment in patients with multiple sclerosis in Sweden

Aims: To evaluate the cost-effectiveness of adding prolonged-release (PR)-fampridine to best supportive care (BSC) versus BSC alone for the improvement of walking ability in patients with MS. Methods: A cost-utility analysis based on a Markov model was developed to model responders and timed 25-foot walk (T25FW) scores, accumulated costs, and quality-adjusted life-years (QALY) in adults with MS and Expanded Disability Status Scale (EDSS) scores between 4 and 7. The analysis was conducted from a Swedish societal perspective. Results: In the base-case analysis, PR-fampridine plus BSC led to a higher QALY gain than BSC alone. The largest direct cost was professional care provision followed by hospital inpatient stays while the indirect cost was the loss of earnings due to days off work. The incremental cost-effectiveness ratio (ICER) for PR-fampridine plus BSC compared with BSC alone was 57,109 Swedish Kronor (kr)/QALY (€5,607/QALY [1 kr = €0.0981762 on 8 April 2021] and $6,675/QALY [1 kr = $0.116890 on 8 April 2021]). All sensitivity analyses performed resulted in ICERs below 500,000 kr (€49,088 and $58,445). Limitations: Resource use data were not specific to the Swedish market. Conclusions: PR-fampridine represents a cost-effective treatment for MS-related walking impairment in Sweden, due to improvements in patients’ quality of life and reduced healthcare resource utilization.

Types of working-life sequences among people recently diagnosed with multiple sclerosis in Sweden: a nationwide register-based cohort study

ObjectivesTo explore sequences of annual states of activity and sickness absence (SA) or disability pension (DP) (SA/DP) among working-aged people with multiple sclerosis (PwMS) as well as characteristics associated with...

The fiscal consequences of public health investments in disease-modifying therapies for the treatment of multiple sclerosis in Sweden

Background and aims: The economic consequences of multiple sclerosis (MS) are broader than those observed within the health system. The progressive nature suggests that people will not be able to live a normal productive life and will gradually require public benefits to maintain living standards. This study investigates the public economic impact of MS and how investments in disease-modifying therapies (DMTs) influence the lifetime costs to government attributed to changes in lifetime tax revenue and disability benefits based on improved health status linked to delayed disease progression.Methods: Disease progression rates from previous MS Markov cohort models were applied to interferon beta-1a, peginterferon beta-1a, dimethyl fumarate, and natalizumab using a public economic framework. The established relationship between expanded disability status scale and work-force participation, annual earnings, and disability rates for each DMT were applied. Subsequently, we assessed the effect of DMTs on discounted governmental costs consisting of health service costs, social insurance and disability costs, and changes in lifetime tax revenues.Results: Fiscal benefits attributed to informal care and community services savings for interferon beta-1a, peginterferon beta-1a, dimethyl fumarate, and natalizumab were SEK340,387, SEK486,837, SEK257,330, and SEK958,852 compared to placebo, respectively. Tax revenue gains linked to changes in lifetime productivity for interferon beta-1a, peginterferon beta-1a, dimethyl fumarate, and natalizumab were estimated to be SEK27,474, SEK39,659, SEK21,661, and SEK75,809, with combined fiscal benefits of cost savings and tax revenue increases of SEK410,039, SEK596,592, SEK326,939, and SEK1,208,023, respectively.Conclusion: The analysis described here illustrates the broader public economic benefits for government attributed to changes in disease status. The lifetime social insurance transfer costs were highest in non-treated patients, and lower social insurance costs were demonstrated with DMTs. These findings suggest that focusing cost-effectiveness analysis only on health costs will likely underestimate the value of DMTs.

Earnings among people with multiple sclerosis in Sweden, by education and occupation

Abstract Background Multiple sclerosis (MS) may affect the individual’s working life. We aimed to 1) investigate the mean levels and distributions of earnings among people with MS (PwMS) before and after MS diagnosis compared to people without an MS diagnosis, and whether such differences in earnings were associated with educational level or occupation and 2) assess the prevalence of sickness absence (SA) and disability pension (DP). Methods Population-based cohort study (10 years prior to 5 years after MS diagnosis) using microdata linked from nationwide Swedish registers of all individuals aged 30-54 with MS diagnosed in 2003-2006 (n = 2553) and references without MS (n = 7584) randomly selected by stratified matching (sex and age). Annual mean earnings, by educational level and type of occupation, were compared with t-tests. Tobit regressions investigated the associations of earnings with individual characteristics. Lastly, the proportions on SA and DP, stratified by educational level and type of occupation, were examined in the diagnosis year and 5 years later. Results Differences in earnings between PwMS and references were observed beginning one year prior to diagnosis and increased with time. PwMS had lower mean earnings for the diagnosis year (difference=SEK 28,000, p-value&amp;lt;0.05), and the difference had more than doubled (p-value&amp;lt;0.05) 5 years later. These differences remained after taking educational level and type of occupation into account. PwMS with university education and/or more qualified occupations had mean earnings most like their respective references’. PwMS had higher prevalence of SA and DP than the references, in both the diagnosis year and 5 years later. Conclusions Earnings of people with MS were lower than references’ already one year before diagnosis, and the gap increased thereafter. Results indicate that educational level and type of occupation are of importance for earnings. Moreover, SA and DP were more common among people with MS. Key messages Our results indicate that working-aged people with MS have less earnings than references already one year before diagnosis and that thereafter this gap in earnings increases with time. Education and occupation were influential in explaining the people with MS’ heterogeneous earnings, with a hierarchal ordering of who maintained similar earnings to their respective peers.

Antibiotics use and risk of amyotrophic lateral sclerosis in Sweden.

Previous animal studies have suggested a disrupted intestinal microbiome in amyotrophic lateral sclerosis (ALS). Due to the known effect of antibiotics on gut microflora, the potential role of antibiotics use on the risk of ALS deserves an investigation. A nested case-control study was conducted using several Swedish national registers. In all, 2484 ALS patients diagnosed between 1 July 2006 and 31 December 2013 were included as cases, and five controls per case individually matched to the case by sex, birth year and area of residence were randomly selected from the general Swedish population. Information on antibiotics prescriptions before ALS diagnosis was extracted from the Prescribed Drug Register for both cases and controls. A conditional logistic regression model was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). After accounting for potential diagnostic delay in ALS by excluding all prescriptions within 1 year before diagnosis, any antibiotics use was associated with a higher risk of ALS. The ORs (95% CIs) were 1.06 (0.94-1.19), 1.13 (1.00-1.28) and 1.18 (1.03-1.35) when comparing 1, 2-3 and ≥4 prescriptions to no prescription (P for trend=0.0069). Similar results were noted for antibiotics used for respiratory infections and urinary tract as well as skin and soft tissue infections. Amongst different individual antibiotics, the risk of ALS was especially increased in relation to more than two prescriptions of beta-lactamase sensitive penicillin (OR 1.28; 95% CI 1.10-1.50). Use of antibiotics, especially repeated, might be associated with a higher subsequent risk of ALS.

Rapidly increasing off-label use of rituximab in multiple sclerosis in Sweden - Outlier or predecessor?

Off-label use of rituximab to treat MS patients in Sweden is high, and the need for long-term safety data may not be met. Our objectives were to assess the rate of rituximab prescription in patients with multiple sclerosis in Sweden and, in addition, to evaluate the safety of rituximab in a single centre for patients with multiple sclerosis. Review of the Swedish MS register was performed to study the number of MS patients treated with rituximab during the last 6years. Investigation also included a retrospective review of medical files in search for possible side effects/adverse events in all adult patients with MS treated with rituximab at Uppsala University Hospital. Presently, in Sweden the rate of rituximab prescriptions in relation to other annually started of disease- modifying drugs in MS is 53.5%. The share of MS patients in Sweden who are treated with rituximab is very high, and also rapidly increasing. Taken into account the off-label use, cases with adverse medical conditions that could possibly be related to rituximab use should be reported thoroughly.

A nationwide survey of the influence of month of birth on the risk of developing multiple sclerosis in Sweden and Iceland

Previous studies have shown that the risk of multiple sclerosis (MS) is associated with season of birth with a higher proportion of MS patients being born in spring. However, this relationship has recently been questioned and may be due to confounding factors. Our aim was to assess the influence from season or month of birth on the risk of developing MS in Sweden and Iceland. Information about month of birth, gender, and phenotype of MS for patients born 1940–1996 was retrieved from the Swedish MS registry (SMSR), and their place of birth was retrieved from the Swedish Total Population Registry (TPR). The corresponding information was retrieved from medical journals of Icelandic MS patients born 1981–1996. The control groups consisted of every person born in Sweden 1940–1996, their gender and county of birth (TPR), and in Iceland all persons born between 1981 and 1996 and their gender (Statistics Iceland). We calculated the expected number of MS patients born during each season and in every month and compared it with the observed number. Adjustments were made for gender, birth year, and county of birth. We included 12,020 Swedish and 108 Icelandic MS patients in the analyses. There was no significant difference between expected and observed MS births related to season or month of birth in Sweden or Iceland. This was even the results before adjustments were made for birth year and birth place. No significant differences were found in subgroup analyses including data of latitude of birth, gender, clinical phenotype, and MS onset of 30 years or less. Our results do not support the previously reported association between season or month of birth and MS risk. Analysis of birth place and birth year as possible confounding factors showed no major influence of them on the seasonal MS risk in Sweden and Iceland.

Costs of illness of multiple sclerosis in Sweden: a population-based register study of people of working age

BackgroundMultiple sclerosis (MS) causes work disability and healthcare resource use, but little is known about the distribution of the associated costs to society.ObjectivesWe estimated the cost of illness (COI) of working-aged individuals with MS, from the societal perspective, overall and in different groups.MethodsA population-based study was conducted, using data linked from several nationwide registers, on 14,077 individuals with MS, aged 20–64 years and living in Sweden. Prevalence-based direct and indirect costs in 2010 were calculated, including costs for prescription drug use, specialized healthcare, sick leave, and disability pension.ResultsThe estimated COI of all the MS patients were SEK 3950 million, of which 75% were indirect costs. MS was the main diagnosis for resource use, causing 38% of healthcare costs and 67% of indirect costs. The distribution of costs was skewed, in which less than 25% of the patients accounted for half the total COI.ConclusionsIndirect costs contributed to approximately 75% of the estimated overall COI of MS patients of working age in Sweden. MS was the main diagnosis for more than half of the estimated COI in this patient group. Further studies are needed to gain knowledge on development of costs over time during the MS disease course.

The External Validity of Mapping MSIS-29 on EQ-5D Among Individuals With Multiple Sclerosis in Sweden.

Background: Mapping can be performed to predict utility values from condition-specific measures when preference-based measures are absent. A previously developed algorithm that predicts EQ-5D-3L index values from the Multiple Sclerosis Impact Scale (MSIS-29) has not yet been externally validated. Aim: To examine the external validity of a previously developed mapping algorithm by testing the accuracy of predicting EQ-5D-3L index values from MSIS-29 among multiple sclerosis (MS) patients in Sweden. Methods: Cross-sectional individual-level data were collected from population-based Swedish registers between 2011 and 2014. Health-related quality of life was assessed through MSIS-29 and EQ-5D-3L at one point in time among 767 individuals with known disability level of MS. A previously developed mapping algorithm was applied to predict EQ-5D index values from MSIS-29 items, and the predictive accuracy was assessed through mean absolute error and root mean square error. Results: When applying the algorithm, the predicted mean EQ-5D-3L index value was 0.77 compared to the observed mean index value of 0.75. Prediction error was higher for individuals reporting EQ-5D values <0.5 compared to individuals reporting EQ-5D values ≥0.5. Mean absolute error (0.12) and root mean square error (0.18) were smaller or equal to the prediction errors found in the original mapping study. Conclusion: The mapping algorithm had similar predictive accuracy in the two independent samples although results showed that the highest predictive performance was found in groups with better health. Varied predictive accuracy in subgroups is consistent with previous studies and strategies to deal with this are warranted.

Occupational Exposure to Electric Shocks and Magnetic Fields and Amyotrophic Lateral Sclerosis in Sweden.

Amyotrophic lateral sclerosis (ALS) has been consistently related to "electric occupations," but associations with magnetic field levels were generally weaker than those with electrical occupations. Exposure to electric shock has been suggested as a possible explanation. Furthermore, studies were generally based on mortality or prevalence of ALS, and studies often had limited statistical power. Using two electric shock and three magnetic field job-exposure matrices, we evaluated the relationship of occupational magnetic fields, electric shocks, electric occupations, and incident ALS in a large population-based nested case-control study in Sweden. Subanalyses, specified a priori, were performed for subjects by gender and by age (less than and more than 65 years). Overall, we did not observe any associations between occupational magnetic field or electric shock exposure and ALS. For individuals less than 65 years old, high electric shock exposure was associated with an odds ratio (OR) of 1.22 (95% confidence interval [CI] = 1.03, 1.43). The corresponding result for the age group 65 years or older was OR = 0.92 (95% CI = 0.81, 1.05). Results were similar regardless which job exposure matrices, exposure definitions, or cutpoints were used. For electric occupations, ORs were close to unity, regardless of age. For welders, no association was observed overall, although for welders <65 years the OR was 1.52 (95% CI = 1.05, 2.21). In this very large population-based study based on incident ALS case subjects, we did not confirm previous observations of higher risk of ALS in electrical occupations, and provided only weak support for associations between electric shocks and ALS.