Amyotrophic lateral sclerosis as a multi-step process: an Australia population study.

Objective: This study sought to investigate whether a multistep process was also evident in an Australian amyotrophic lateral sclerosis (ALS) population. Methods: Mortality rates for ALS patients (years 2007-2016) were obtained from the Australian Institute of Health and Welfare (AIHW). The log incidence of ALS, as reflected by crude mortality rates, was regressed against log of age disease onset. Results: From a total population of 24 million, 6524 cases of ALS were identified. A linear relation between the log incidence and log age was identified, with r(2) value of 0.99, indicating that ALS is a multistep process. The linear slope estimate was 5.0, suggesting that six steps were required for development of ALS. Conclusions: This study established a linear relationship between log incidence and log age onset in an Australia ALS population, consistent with a multistep process. Identification of these steps will likely be of therapeutic benefit in ALS.