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Study Suggests MS Drugs Delay Progression of Disability in Relapsing MS

December 7, 2007

A large-scale analysis suggests that disease-modifying drugs for MS (specifically, interferon beta-1a, interferon beta-1b or glatiramer acetate) are effective in reducing disability progression in people whose MS started with relapses. Murray Brown, PhD (Dalhousie University, Halifax, Nova Scotia) and colleagues developed estimates of drug effectiveness based on data from 590 people with MS treated with the drugs. Compared to estimated rates of progression before treatment, therapy was estimated to reduce progression in the EDSS by 90-105% over the course of the period studied in people with relapsing MS.  The reduction in progression of the EDSS was 100-112% for patients with relapsing-remitting MS but only 8-22% for those with secondary-progressive MS. Although this study was based on clinical observations and not on a well-controlled clinical trial, it provides much-needed evidence of the longer-term benefit of therapy.


Disease-modifying drugs(DMDs) have been shown to reduce future disease activity for many individuals with relapsing forms of MS by reducing the frequency and severity of clinical attacks,  the accumulation of tissue damage seen on MRI, and in some cases the progression of disability over the relatively short duration of the studies (usually approximately 2 years). However, research proving that these drugs can delay the progression of disability over the long term is lacking.

In this novel study (Neurology2007 Oct 9;69(15):1498-507),funded by Health Canada, the MS Society of Canada, Nova Scotia Health Research Foundation and others, Murray Brown, PhD  and colleagues used the Dalhousie MS Research Unit’s database to track the course of 590 people with relapsing forms of MS. The database includes 25 years of clinical data on people with MS, including up to six years of data on people whose three classes of DMDs were paid for by Nova Scotia’s Department of Health from 1998 to 2004.

The study population included 390 people with RR MS and 200 people with SP MS at an average of 8.9 years since disease onset. Because this study was “observational” meaning that the investigators were looking at this group of patients in a real-world setting and not in a controlled clinical trial annual EDSS scores (a scale used to measure disease activity) were not always available, but were estimated before, during and after treatment using statistical models.

The results suggest that the DMDs significantly delayed estimated EDSS progression in both groups combined by 90-105%. The effect was greater in those who began treatment and remained classified as RR MS in 2004 (100-112%) than in those who began treatment as RR MS or SP MS and ended up being classified as SP MS in 2004 (8-22%).  Switching treatments  was followed by significant estimated EDSS progression in those with SP MS, and stopping treatment also resulted in significant estimated EDSS progression in the group as a whole, although not significantly in RR MS and SP MS separately.  The authors conclude that “Because Nova Scotia estimates of DMD relative treatment effect size for RRMS subgroups are very large (100% to 110%) for the initial DMD, treatment may temporarily arrest disability progression or even reduce disability slightly.+ (Page 1506)

In an accompanying editorial, Maria Trojano, MD (University of Bari, Italy) applauds the use of this type of study to determine the long-term effects of MS treatments. “The popular belief that only RCTs [randomized controlled trials] produce trustworthy resultsand that all observational studies are misleading does a disserviceto patient care, clinical investigation, and education of healthcare professionals,” she writes. “We should celebrate an enhanced qualityof observational studies and the opportunity it provides fora less expensive evaluation of therapies in clinical medicine.”

Aaron Miller, MD, Chief Medical Officer of the National MS Society, adds, “This study adds important information to our knowledge about DMDs, and hopefully will inspire future observational and controlled studies to further report on their ability to delay disease progression. These drugs remain the best defense available to reduce future disease course of MS.”

Further information about the DMDs is available on our Web site

-- Research and Clinical Programs Department

+RR MS Relapsing-remitting MS is a course of MS in which clearly defined flare-ups are followed by partial or complete recovery periods.**SP MS Secondary-progressive MS, an initial period of relapsing-remitting MS, followed by a steadily worsening disease course with or without occasional flare-ups or minor recoveries.

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