Impact of disease-modifying therapies on the survival of patients with multiple sclerosis in Taiwan, 1997-2008

Background: Little is known about the impact of disease-modifying therapies (DMTs) on the survival of patients with multiple sclerosis (MS) throughout the world. Objective: We conducted this study to investigate the association between DMTs and the survival of patients with MS in Taiwan. Methods: A total of 1,240 individuals who had a primary diagnosis of MS and a seriously disabling disease certificate in Taiwan between 1 January 1997 and 1 December 2008 were followed up until 31 December 2009 to check what medical services were provided to them and whether they had a date of death recorded in the national mortality database. Disease-modifying therapies, including interferon beta 1-a, interferon beta 1-b and glatiramer acetate, were included in the analysis. Follow-up information was available on all individuals; the mean follow-up time was 54.3 months (standard deviation [SD] 38.8 months). A Cox regression model was utilized to reveal the effect of DMTs on MS mortality by controlling for sex, age, residence, insurance amount and geographic region. Results: Eighty-eight of the 1,240 individuals (7.1 %) died. The risk of mortality in the first year showed a 7-fold age- and sex-standardized mortality rate increase over that of the general population in Taiwan. In the fully adjusted model, the final independent risk factors were older age, rural residence, lower economic status and lower adherence to DMTs. Conclusion: The results of this study support the notion that DMTs can improve the survival of patients with MS, and show that individuals with the risk factors of older age, rural residence and lower economic status had a higher MS-related mortality risk in Taiwan.