Abstract
Background The Greater Hobart region (42.5°S) of Tasmania has consistently had the highest recorded prevalence and incidence rates of MS in Australia. We re-assessed MS epidemiology in 2009–2019 and assessed longitudinal changes over 68 years.
Methods Cases recruited from clinic-based datasets and multiple other data sources. 2019 prevalence and 2009–19 annual incidence and mortality rates estimated, and differences assessed using Poisson regression.
Results 436 MS cases resident on prevalence day were identified. Prevalence 197.1/100,000 (147.2/100,000 age-standardised), a 48% increase since 2009 and 4.6-fold increase since 1961. 2009–19 incidence rate 5.9/100,000 person-years (6.1/1000,000 age-standardised), a 2.8-fold increase since 2001–9 and 60% since 1951–61. 2009–19 mortality rate 1.5/100,000 person-years (0.9/100,000 age-standardised), comparable to 2001–9 (1.0/100,000) but reduced by 61% from 1951–59 (2.1/100,000). Standardised mortality ratio decreased from 2.0 in 1971–79 to 1.0 in 2009–19. Female:male prevalence sex-ratio was 2.8, comparable to the 2009 value (2.6), incidence sex-ratio (2.9) increased from 2001–9 (2.1). Comparisons with Newcastle, Australia (latitude=32.5°S) demonstrate a near complete abrogation of the latitudinal prevalence gradient (ratio=1.0) and incidence (ratio=1.1), largely attributable to changing Hobart demography.
Conclusions Prevalence and incidence of MS continue to increase significantly in Hobart, alongside marked reductions in mortality and increased case longevity. The marked increase in incidence is of particular note and may reflect changes in MS risk behaviours decades ago including changes to sun exposure, obesity rates, and smoking behaviours, particularly in females. Falling mortality contributes to increase longevity and prevalence and likely reflects improved overall MS health care and implementation of DMT therapy.
