The natural history of untreated multiple sclerosis has been studied for over a hundred years. The most pessimistic data show that the risk of requiring a cane or worse is 50% at 10 years and 90% at 25 years. This fits the notion that only 10% of untreated patients have “benign” MS, meaning little or no disability at 25 years. Other studies indicate that the course may be less ominous.

"MS patient using cane to walk"
“MS patient using cane to walk”

Be that as it may, it has been difficult to prove that the widespread use since the 1990’s of disease-modifying-therapy has truly reduced long term disability. Two important studies, from British Columbia and Minnesota, have concluded that the rate of disability progression has not changed from 1975 to 2009 in one study and, from 1991 to 2000 in the other.

Disability progression has not changed from 1975 - 2009
“Disability progression has not changed from 1975 – 2009.”

A new study counters the bad news. It captured 80% of all MS patients in Sweden, where the prevalence of MS is high, diagnosed between 1995 and followed for at least 7 and a median of 8.5 years. This was a treated population. It showed that the risk of reaching disability milestones has significantly decreased in the last decade in patients with relapsing onset MS, although, disappointingly, not in progressive MS. The progressive group was not uniformly treated and are more recent highly efficacious medications may make a difference in years to come.

See the article by Beiki and et al in JAMA Neurology, June 2019.

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