Ramping down MS severity

A 10-year study shows that MS may not become
debilitating for all sufferers.

By Brian Hoyle

Up until now, the clinical view of multiple sclerosis (MS) has been that while the severity of the decline in physical functioning can vary among people, a gradual drop was inevitable. A report in the January 13 issue of Neurology calls this assumption into question by showing that 70% of MS sufferers did not suffer significant decline over a 10-year period.

Researchers from the Mayo Clinic in Rochester, Minnesota conducted a 10-year follow-up of 162 patients from a cohort originally assessed in 1991, making it the most comprehensive study ever done on how MS symptoms change over time. They were able to locate all but one of the original patients. Twenty-four patients had died in the intervening years. The 138 patients who were still alive all agreed to be interviewed and allowed an examination of their medical records.

The authors determined the Kurtzke Expanded Disability Status Scales (EDSS) scores for the 138 living patients. EDSS scores quantify the disability in MS based on eight so-called functional systems, which include vision, bowel and bladder control, and sensory and cerebral functioning. A higher score indicates worsening disability. Scores were also determined for the 24 deceased patients by looking at their medical records from within a year of their death.

The mean change in EDSS for the 162 patients was only a single EDSS point. Only 20% of the patients displayed an EDSS change of two points or more. Of the 66 patients whose scores were three or less in 1991, 83% could walk without the use of a cane 10 years later. The 33 patients whose 1991 EDSS scores were three to five didn't fare as well. Forty-eight percent required a cane to walk, and 3% required a wheelchair in 2001. For patients whose EDSS scores were six to seven in 1991, 51% percent required a wheelchair 10 years later. So those patients who were more physically affected to begin with displayed the most deterioration.

Overall, less than half of the participants developed worsening disabilities over the decade. Of the 99 patients who were walking unassisted in 1991, 71 were still doing so in 2001. Only about 20% who did not need a wheelchair in 1991 required one 10 years later.

"The fact that most MS patients don't get progressively worse over 10 years is the really great news," said neurologist Moses Rodriguez, MD, who led the Mayo Clinic team.

The geographic location of the study is important. For as-yet unknown reasons, MS is more common in the northern areas than southern climates. But the real punch comes from the study's size and follow-up period. "This astounding continuity gives the Mayo Clinic study a statistical power rarely seen in studies of living patients, and not likely to be equalled in subsequent efforts," said Rodriguez.

The finding that MS doesn't appear to lead to a downward spiralling of mobility in the majority of those who are affected is hugely encouraging to the Mayo Clinic researchers, who are also involved in treating MS patients. "Natural history studies like this one can provide a long-term benchmark against which outcomes of treatment and placebo groups can be compared, and in addition can help in counselling patients because it allows them to envision a likely future," said Sean Pittock, MD, first author of the Neurology paper.

MS affects 35,000 to 50,000 Canadians and some 200,000 Americans. In Canada, which has one of the highest rates of MS in the world, the disease is the most common neurological disorder affecting young adults.