Incidence and mortality of ALS: a 42-year population-based nationwide study

Background and aim: Recent studies have suggested that the incidence rate (IR) and the rate of death (MR) of amyotrophic lateral sclerosis (ALS) are increasing. Still, it remains unclear whether this is due to improved case ascertainment or represents a true increase. We examined the development in the incidence and mortality of ALS in Denmark for 42 years.

Methods: We retrieved individual-level data of all patients aged above 18 years with first-time ALS diagnosed at any Danish department of neurology. The IR and MR were calculated based on data from 1980 to 2021, stratified by gender and age.

Results: We identified 5,943 patients with ALS and identified a total of 5,069 deaths in the nationwide population. Overall, the IR was 3.4 per 100,000 persons per year (95% CI 3.4-3.5). ALS incidence rose gradually during the study period, and the IR was 2.8 times higher (95% CI 2.4-3.2) when comparing the latest period (2018-2021) with the first (1980-1983). Parallel to the IR, the MR increased over time and was associated with male gender and rose with age at diagnosis, peaking in the 70-79-year age group.

Conclusion: In Denmark, the IR and MR of ALS increased threefold from 1980 to 2021, with steadily increasing risk related to male gender and in particular to higher age. Considering our aging societies, the number of elderly patients with ALS can be expected to increase considerably.