Prevalence survey of multiple sclerosis in the Australian Capital Territory

Aim: This study sought to obtain an estimate of the prevalence of multiple sclerosis (MS) in the Australian Capital Territory (ACT), a largely urban region that differs climatically and socioeconomically from other Australian cities examined in previous MS surveys. Methods: Prevalence day was chosen to coincide with the 1996 National Census. All ACT neurologists' records for the previous 5 years were examined and cases of MS were classified according to the published diagnostic criteria of Rose et al. and Poser et al. Results: By the criteria of Rose et al., as used in previous Australian surveys of MS, prevalence was 79.9/100 000 (95% confidence interval (CI) = 63.4-99.2) for females, 32.8 (22.7-46.2) for males and 56.7 (43.1-74.1) for all people, standardized to the 1996 population. Standardized to the 1981 population for direct comparison with 1981 surveys in New South Wales, the prevalence of MS in the ACT was still unexpectedly high, particularly for females. Using the criteria of Poser et al., the prevalence of MS standardized to the 1996 population was 70.6/ 100 000 (95% CI = 58.4-85.3) for females, 28.0 (20.3-37.8) for males and 49.5 (42.2-58.2) for all people. There was evidence from a relatively short duration of disease in the ACT sample that some persons with long-standing MS had been missed in the survey and therefore that the prevalence of MS observed in the ACT was an underestimate. Conclusions: The survey found an unexpectedly high prevalence of MS in the ACT. Possible reasons for this are discussed. There was no evidence that the advent of magnetic resonance imaging had increased the numbers of persons diagnosed with MS in the present survey.