While multiple sclerosis may be diagnosed in persons of almost any age, including toddlers and senior citizens, it is most commonly diagnosed in persons who are 20-40 years of age. Less is known about how MS affects those who develop symptoms after the age of 50. So researchers in British Columbia conducted a retrospective study (1980-2004) in adults diagnosed with MS (n=5985).
Late-Onset MS (LOMS) vs Adult-Onset MS (AOMS)
Patients were separated into two groups: those with late-onset MS (symptom onset at ≥50 years of age, n=358) or adult-onset MS (symptom onset between ages 18 and <50, n=5627). Researchers looked at patient characteristics and exposure to disease-modifying therapy (DMT), specifically interferon-beta (IFNð›½), as well as the association between DMT use and disability progression in older relapsing-onset MS adults. IFNð›½-treated relapsing MS patients aged ≥50 (regardless of onset age, n=90) were compared with contemporary (n=171) and historical (n=106) controls.
Results of the study
Among 5985 adults diagnosed with MS, approximately 1 in 16 had late-onset MS. The LOMS group had proportionally more patients with a primary-progressive disease course and men with motor onset symptoms than the AOMS group. The majority of the LOMS cohort (57.5 percent) had a relapsing disease course of which 30.6 percent were prescribed a DMT (most commonly IFNð›½) compared to 41 percent of the relapsing-onset AOMS group.
Among older adults with relapsing-onset MS, no significant association was found between IFNð›½ use and progression of disability (confirmed EDSS ≥6) when compared to contemporary (hazard ratio [HR]: 0.46) or historical (HR: 0.54) controls. In other words, IFNð›½ exposure was not significantly associated with reduced disability in older MS patients.
Disease characteristics differ in patients who develop MS at a later age and this study shows that MS disease-modifying therapies may not be as effective in this older group.
Older adults underrepresented in clinical trials
The treatment of older adults with MS can be challenging with the lack of evidence-based guidelines specific to this growing cohort of patients. For years, older people have been underrepresented in pharmaceutical clinical trials. The average age of participants in early pivotal trials for IFNð›½ drugs was 35, while those over the age of 50 or 55 were excluded. More recent studies have increased upper age limits to 60 or 65 years old. Also, older people tend to have more comorbidities, a common reason for exclusion from many clinical trials.
Authors of the Canadian study emphasize that further studies are needed to develop evidence-based guidelines for this special population. Information regarding the impact of DMTs in older MS patients is needed for a number of reasons:
- Older adults with MS are typically treated using therapeutic guidelines originally established for younger adults, without direct evidence to support this practice.
- Aging affects the pharmacodynamics and pharmacokinetics of drugs, as well as the immune system, thus immunomodulatory therapies might have a different effect in older MS patients.
- Follow-up time in clinical trials is typically 2-3 years, too short to capture the longer term progression profile of patients.
- Clinical trial settings differ from real-world settings, especially in respect to patient characteristics, such as comorbidities and the motivation or ability to adhere to medications.
- As the prevalence of older people living with MS continues to increase with an aging population, there is an important need to better understand the characteristics of older patients including their potential response to drug treatments for MS.
While researchers gather evidence that shows particular therapies are less effective in older MS patients, it is important to explore more effective options.
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Shirani A, Zhao Y, Petkau J, et al. Multiple sclerosis in older adults: the clinical profile and impact of interferon Beta treatment. Biomed Res Int. 2015;2015:451912. doi: 10.1155/2015/451912. Epub 2015 Apr 1.