The incidence and prevalence of motor neurone disease in South Australia

Background: Motor neurone disease (MND) is a neurodegenerative disease that leads to significant morbidity and mortality. The Global Burden of Disease (GBD) project estimated the MND all-age global prevalence is 4.5 (95% confidence interval (CI)=4.1–5.0) per 100,000 persons and the all-age incidence of 0.78 (95% CI = 0.71–0.86) per 100,000 person-years. Whether the prevalence and incidence of MND within South Australia using registry data is in keeping with these global estimates has not been studied. 

Objective: To describe the prevalence and annual incidence rates (IRs) of MND in South Australia between 2017 and 2019. 

Methods: A retrospective cohort study calculating the point prevalence of MND on 31 December 2017, 2018 and 2019 utilizing data from the Australasian Motor Neurone Disease Registry (AMNDR). The annual IRs between 2017 and 2019 were calculated using population data reported in the 2016 Australian census and age-standardized rates utilized the world population from the United Nations Population Division’s World Population Prospects. 

Results: A total of 256 MND patients were identified, of whom 114 were alive on 31 December 2019. Based on the 2016 population of 1,676,653 persons, the estimated prevalence was 6.79 per 100,000 persons. The crude IR for the all-age South Australian population was 3.34 per 100,000 person-years (95% CI, 2.85–3.88). The estimated annual IRs based on those ≥20 yo were 4.98 (3.84–6.35), 3.68 (2.71–4.88), and 4.21 (3.17–5.49) per 100,000 person-years for 2017, 2018, and 2019, respectively. 

Conclusion: The crude prevalence and incidence of MND in South Australia were considerably higher than global estimates. This may reflect higher rates of the disease or higher rates of case ascertainment compared to the GBD project.