Background: Multiple sclerosis (MS) has a low prevalence in Hong Kong.
Objective: To reassess MS prevalence in Hong Kong and to examine associated risk factors for relapsing-remitting type MS patients to reach Kurtzke's Extended Disability Status Scale (EDSS) of 6.0, i.e. when walking aid was needed.
Design: Retrospective observational study on MS patients over 11 years.
Setting: Three tertiary hospitals in Hong Kong.
Results: A hundred and six patients were recruited. Female to male ratio was 3.2:1 and the prevalence was 4.8 per 100,000. 95 were relapsing-remitting (RR) type. The mean disease duration was 12.7 years (range: 1-45 years) and the duration of follow up was 11.0+/-0.8 (mean+/-SE) years. The initial mean EDSS was 1.59 and the latest mean EDSS was 4.26. 38 (40%) RR type MS patients progressed to EDSS 6.0 after a mean duration of 6.0 years. With Cox regression analysis, patients with older age (>35y) of onset (HR 2.57; 95% CI:1.29-5.11), higher EDSS of 2.0 or more upon presentation (HR 2.19; 95%CI: 1.12-4.26) were associated with progression to EDSS of 6.0, while there was a tendency towards slower disease progression for patients initially presenting with optic symptoms (HR 0.52; 95%CI: 0.23-1.16). The number of relapses and use of interferon could not be shown to have significant effect on disease progression.
Conclusions: The local period prevalence ratio of MS was 4.8 per 100,000. Older age of onset and higher EDSS upon initial presentation were independent predictors for progression to EDSS of 6.0.