People with late-onset multiple sclerosis (MS) tend to more rapidly rise in disability scores than younger patients with early onset MS, according to study in MS patients in Kuwait that compared their scores during follow-up consultations.
Typically, the first symptoms of multiple sclerosis occur between the ages of 18 and 40, with an estimated 20 percent of all MS patients experiencing first symptoms after the age 40. But late-onset MS appears to be increasing in the general population, the researchers said in their study, “Is Time to Reach EDSS 6.0 Faster in Patients with Late-Onset versus Young-Onset Multiple Sclerosis,” published in the journal Plos One.
Later onset disease can also be a diagnostic challenge, since its clinical presentation and course seems to be different from those with earlier onset MS. Few studies have traced the natural progression of late-onset disease.
Researchers at various universities and hospitals in Kuwait gathered demographic and clinical information on MS patients — presentation at onset, disease duration, number of relapses, and expanded disability status scale (EDSS) scores — using data from the Kuwait National MS Registry, established in 2010.
Their focus was time from baseline to sustained disability, defined by an EDSS score of 6.0. This score has been indirectly associated with disability progression, and is defined as the need for “intermittent or unilateral constant assistance [cane, crutch, or other] … to walk about 100 meters with or without resting.”
In total, the study included 99 (10.7%) late-onset patients with a median age of 45.9, and 804 (89.3%) early onset patients, whose median age was 26.6.
EDSS analysis during follow-up found that 19.2% of the late onset group and 15.7% of early onset patients reached EDSS 6.0. Late-onset MS patients reached this higher disability level much more quickly — a median of 6.5 years — than patients diagnosed with MS earlier in life, a group that took a median of 12.8 years to reach 6.0 on the EDSS scale. This difference, the researchers said, represented a 3.6-increased likelihood of late-onset patients reaching EDSS 6.0 compared to early onset patients.
Male gender and spinal symptoms at onset of MS were also significantly associated with increased risk, 1.85 and 1.47, respectively, of reaching EDSS 6.0 in a shorter time.
During this follow-up, a higher proportion of late-onset patients (26.3%) progressed to a more severe disease state — secondary progressive MS — compared to those with earlier onset (17.8%). Researchers also reported that spinal cord disease symptoms at onset were more prevalent among late-onset (46.5%) than early onset (32.3%) patients.
“LOMS [late-onset] patients attained EDSS 6.0 in a significantly shorter period that was influenced by male gender and spinal cord presentation at MS onset,” the researchers concluded, adding, “Since the prevalence of LOMS will continue to increase, there is a need to better understand the natural history of these patients and their response to earlier institution of treatment.”