Relapsing and progressive MS: the sex-specific perspective

Abstract

Background: Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease whose aetiology is not fully understood. The female sex is clearly predominant, with a sex ratio between 2 and 3. In primary progressive MS the sex ratio almost balances out. Since the age at onset is higher for patients with progressive onset (POMS) than for relapsing onset (ROMS), it can be hypothesized that the age at onset is a decisive factor for the sex ratio.

Methods: To address this aspect, we compare clinical and demographic data between females and males for the different disease courses within the population of the German MS Register by the German MS Society. Only patients with complete details in mandatory data items and a follow-up visit since 01. Jan 2018 were included.

Results: A total of 18,728 patients were included in our analyses, revealing a female-to-male ratio of 2.6 (2.7 for patients with ROMS and 1.3 for POMS). The age at diagnosis is higher in patients with POMS (43.3 and 42.3 years for females and males versus 32.1 and 33.2 years, respectively). Females irrespective of disease course are statistically significantly more often affected by cognitive impairment (POMS: p = 0.013, ROMS: p = 0.001) and depression (POMS: p = 0.002, ROMS: 0.001) and suffer more often from pain (POMS and ROMS: p < 0.001). Fatigue is significantly more often seen in females with ROMS (p < 0.001) but not in POMS. Females with ROMS retire significantly (p < 0.001) earlier (42.8 versus 44.2 years) and to a greater extent than males (28 versus 24%). Disease progression was similar for women and men.

Conclusion: Our analysis shows that clinical and demographic data differ more between disease courses than between men and women. For pain, depression and cognitive impairment the female sex is the decisive factor. Whether these factors are responsible for the earlier retirement of females with ROMS is not clear. Appropriate measures for optimization of symptomatic treatment as well as to promote employment should be taken.

Keywords: age of onset; multiple sclerosis; progressive MS; relapsing MS; sex ratio.

Figure 1.

Age at onset for females (red) and males (blue) and progressive onset multiple sclerosis (POMS; left) and relapsing onset multiple sclerosis (ROMS; right).

Figure 2.

Frequency of initial symptoms in females and males, broken down by disease course [relapsing onset multiple sclerosis (A) and progressive onset multiple sclerosis (B)]. p-values: *p < 0.05, **p < 0.01

Figure 3.

Frequency of current symptoms in females and males, broken down by disease course [relapsing onset multiple sclerosis (A) and progressive onset multiple sclerosis (B)]. p-values: *p < 0.05, **p < 0.01.

Figure 4.

The temporal course of disability in women (red) and men (blue) in their respective disease courses and broken down by age and disease duration. (A) EDSS of patients with relapsing onset multiple sclerosis (ROMS) broken down by age. (B) EDSS of patients with progressive onset multiple sclerosis (POMS) broken down by age. (C) EDSS of patients with ROMS broken down by disease duration (years). (D) EDSS of patients with POMS broken down by disease duration (years). The solid line shows the proportion of patients with the corresponding EDSS (left axis). The dotted line shows the percentage of patients who have not reached an EDSS of 6 (right axis). EDSS, Expanded Disability Status Scale.