Efficacy of beta-interferon in relapsing multiple sclerosis among Hong Kong Chinese

Abstract

INTRODUCTION: Multiple sclerosis (MS) is the most common central nervous system inflammatory demyelinating disorder characterised by relapsing neuroinflammation affecting different regions of the brain, cord, and optic nerves. Beta-interferon (β-IFN) is a first-line disease-modifying drug for MS. METHODS: We retrospectively studied the response to β-IFN of Chinese MS patients followed up in Queen Mary Hospital (QMH). RESULTS: A total of 92 Chinese MS patients who had been followed up by the Neurology Clinic of QMH with follow-up data available were studied. Their mean age at MS onset was 28.8 (range, 12-56) years, mean disease duration 163.3 (range, 6-468) months, and 71 (77.2%) were female. Of the 92 patients, 49 (53.3%) were treated with β-IFN and 41 (44.6%) received β-IFN for 12 months or longer. These 49 patients were studied in detail. Their median duration of β-IFN therapy was 32 (range, 5-204) months and median time from clinical onset to initiation of β-IFN therapy was 39 (range, 2-348) months. The mean annualised relapse rate (ARR) of the 49 patients decreased significantly from pre-treatment 1.19 to post-treatment 0.37; P=0.001 (median, 0.75 to 0.00). Of the 49 patients, 34 (69.4%) had ARR reduction by 30% or more. The median modified Rio score, a measure of clinical relapse and MRI disease activity, was 0.71 at 12 months of β-IFN therapy. Concerning disability, the mean Expanded Disability Status Scale (EDSS) score before β-IFN and after β-IFN therapy/at latest follow-up were 1.8 and 3.3 respectively (median, 2.0 and 2.5, respectively). Overall, 34 (37%) patients had EDSS score of 6 or more at the latest follow-up. Kaplan-Meier analysis reviewed the median time to EDSS score 6 of these 34 patients was 100 months, and there was no difference in median time to EDSS score 6 between those with and without β-IFN therapy for 12 months or longer (85 months vs 100 months; P=0.937 by log-rank test). CONCLUSION: β-IFN therapy for 12 months or longer is moderately effective for prevention of clinical relapse but may not prevent/slow down disability progression in relapsing MS among Hong Kong Chinese.