ST. LOUIS –
Whether the pathophysiology is different, or if the disease is simply compounded by the effects of aging, is uncertain. It is likely, however, that patients with late onset are at greater risk of misdiagnosis and delayed treatment, said Mattia Wruble, a 4th-year medical student at the University of Virginia.
The reason is that MS usually presents in young women as relapsing-remitting disease, but late onset is more typically primary progressive, with a higher proportion of men, which is something that has been demonstrated in previous work and also found in the new study.
“What we didn’t expect to find,” however, was greater “disability and higher disability accrual rates” across all subtypes. Late-onset MS “is a worse disease, a more severe disease” that might even need different treatment options, Ms. Wruble said at the American Neurological Association annual meeting.
Ms. Wruble and colleagues compared the charts of 1,381 patients with MS onset before age 50 years, at a median age of 33 years, with 143 patients whose symptoms began at age 50 years or later, at a median of 55 years.
It was one of the largest late-onset MS samples to date. Incidence of the condition is on the rise, but research has been limited. The investigators hoped to address a need for “a better and more thorough characterization of” the disease to aid treatment and improve outcomes, Ms. Wruble said.
There was a higher proportion of men in the late-onset group, 38% vs. 26%. About 75% of patients with early onset had relapsing remitting disease, and 10% had primary progressive disease. The late-onset group was about evenly split between relapsing-remitting and primary progressive MS (P less than .001).
Patients with late onset MS also had a higher degree of disability at their most recent visit across all subtypes (median Expanded Disability Status Scale score of 5 versus 3), despite having a shorter duration of disease (mean 12 vs. 17 years from symptom onset).
Overall disease accrual rate in the late-onset group was twice that of early-onset group, a decline of 0.647 points per year on the EDSS versus 0.357 points (P less than .001). The finding held when limited to early and late relapsing-remitting cases. The accrual rate for late-onset primary and secondary progressive MS was 1.5 times that of early-onset cases.
Transition to secondary progressive disease also was faster in the late-onset group, a mean of about 7 years versus 15-19 years. Patients with late onset also were more likely to have a history of smoking.
The cerebrospinal fluid in late-onset MS generally has fewer unique oligoclonal bands, which are part of the McDonald diagnostic criteria for MS. “The McDonald criteria were made for patients between 20 and 50 years old; maybe they are not the best criteria to diagnose this late-onset group,” Ms. Wruble said.
There was no external funding, and Ms. Wruble had no disclosures.
SOURCE: Wruble M et al. ANA 2019. Abstract S234.