Epidemiology of amyotrophic lateral sclerosis: a population-based analysis, 2015-2020

Background: Epidemiological data on amyotrophic lateral sclerosis (ALS) in Spain have primarily been derived from small cohort studies, with limited information on survival and comorbidities. This study presents a 10-year follow-up of a large, well-phenotyped community-dwelling ALS cohort in Catalonia, Spain. Methods: This observational study utilized data from the Information System for the Development of Research in Primary Care (SIDIAP), which includes health records for 6,301,095 individuals from 2015 to 2020. We assessed ALS incidence, prevalence, comorbidities, territorial distribution, mortality, and survival times. Results: From 2015 to 2020, 1173 ALS cases were identified, with a median age at diagnosis of 68 years, and 50.4% of cases were female. Incidence and prevalence were estimated at 2.39 per 100,000 person-years and 7.98 cases per 100,000 persons. Dementia was present in 6.8% of cases before ALS diagnosis, while depression and/or anxiety affected 45.7%. Median survival from diagnosis was 2.19 years. Multivariate analysis identified older age at diagnosis (HR: 1.04, 95% CI: 1.04-1.05, p value < 0.001), alcohol abuse (HR: 1.56, 95% CI: 1.04-2.56, p value = 0.017), history of stroke (HR: 1.47, 95% CI: 1.07-2.04, p = 0.006), and dementia (HR: 1.57, 95% CI: 1.18-2.12, p value = 0.001) as independent predictors of mortality. Conclusions: ALS incidence and prevalence in Catalonia are higher than previously estimated for Spain and align closely with rates observed in other Western countries. Older age at diagnosis, alcohol abuse, stroke history, and dementia were all significantly associated with reduced survival. These findings underscore important risk factors affecting prognosis, offering valuable insights into ALS progression.