Steady rise in MS seen among adults older than age 50 in Italy
Incidence of late-onset MS tracked in Sicilian province from 2005 to 2020
The incidence of late-onset multiple sclerosis (LOMS), a form of multiple sclerosis (MS) that begins after age 50, has risen steadily between 2005 and 2020, particularly among people in their 60s, scientists in Italy report.
“Our study is the first population-based study describing the IR [incidence rate] of LOMS in a 16-years time period finding an increasing IR over the time,” the researchers wrote. Data show “a gradual age shift is taking place from LOMS to very late onset multiple sclerosis … defined as MS whose onset occurs at the age of 60 years or older.”
The study, “Incidence of late onset multiple sclerosis in Italy: a population-based study,” was published in Scientific Reports.
MS as a late-onset disease tends to show greater disability, cognitive issues
Most often, MS is diagnosed in younger adults between the ages of 20 and 40, but the disease can affect people of all ages. LOMS, which is marked by a diagnosis after age 50, can differ from the more commonly known disease.
For example, while MS is about three times more common in younger women than men, this sex gap tends to decrease with LOMS. Primary progressive MS, which affects about 10% of all younger adults with MS, is slightly more prevalent in people with LOMS. These older adults also tend to have a higher disability level and greater cognitive issues at the time of diagnosis.
A few studies have reported a rising incidence of LOMS in recent decades, meaning that the number of new cases per year has increased. Whether this also occurred in Italy, a country with a high incidence of MS, is not known.
Scientists, mostly with the University of Catania, examined the number of new LOMS cases diagnosed between 2005 and 2020 across that province in eastern Sicily.
Over that period, a total of 183 people were diagnosed with LOMS at hospitals and MS centers there. Their average age was 55.8 at diagnosis, 38.2% were men, and 21.3% had PPMS. Their median Expanded Disability Status Scale (EDSS) score was 2.5, indicating minimal to mild disability.
Rise in incidence rates particularly seen among patients ages 60 to 69
The incidence rate of LOMS during those years was 2.87 per 100,000 person-years (a measurement that combines the number of people studied with the time they were observed). Results were adjusted to the Catalan population, but rates were similar when adjusted to the Italian or European populations.
A rise in incidence rates from 2.54 per 100,000 between 2005-2010 to 3.32 per 100,000 between 2016-2020 was noted. This increase was particularly more evident in patients 60 to 69 years old when diagnosed — rising from 1.12 to 3.12 cases per 100,000 person-years over those time periods.
“Possible explanations to this gradual increase in the age at onset can be attributed either to the aging population or to the improvement in the diagnostic accuracy, although a possible role of changing environmental risk factors cannot be ruled out,” the researchers wrote.
Sex differences among these patients, relative to younger patients, also were noted over time. Women had a higher incidence rate in the 50-59 age group, but this gap decreased at older ages, with men and women being diagnosed at more comparable rates.
“This testifies a reduction in the female-to-male gradient in the incidence of MS, with the disappearance in subjects over the age of 60,” they noted. These patterns align with prior research suggesting that sex-related differences in MS incidence tend to decrease with age.
Older patients in study less likely than others to be prescribed a DMT
The treatment landscape for LOMS also can differ from that of younger patients. While disease-modifying therapies (DMTs) can alter the course of MS, 38.5% of LOMS patients in the study received no treatment.
This may be due to limited clinical trial data for older adults, concerns about medication safety, or a preference for therapies with fewer side effects. “There is still paucity of information regarding efficacy of disease-modifying therapies in LOMS,” the researchers wrote.
Although conducted in Italy, the study’s findings could reflect broader trends as populations age worldwide, the team suggested. Study findings also underscore the need for better diagnostic tools and treatment options tailored to older MS patients.
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