Having second autoimmune disease doesn’t speed up MS progression

Having a second autoimmune disease does not accelerate disability progression in people with multiple sclerosis (MS), according to a large study.

Among 1,230 MS patients followed over time, those living with an additional autoimmune condition that doesn’t affect the nervous system reached disability milestones at the same rate as those without one, even after accounting for age, sex, and time to treatment.

‘Our findings suggest that concurrent [autoimmune diseases] do not independently accelerate long-term disability progression in MS,’ researchers wrote in the study.

MS is an autoimmune disease in which the immune system mistakenly attacks the brain and spinal cord. It frequently occurs alongside other autoimmune diseases, including those that affect the liver (hepatitis), the digestive tract (inflammatory bowel disease), the skin (psoriasis), the eyes (uveitis), and the joints (arthritis).

Because MS and these conditions share an autoimmune basis, researchers believe they may also share underlying biological pathways and genetic risk factors.

In fact, studies have found that people with MS and their relatives face a higher likelihood of developing another autoimmune condition, suggesting a genetic relationship.

But research examining whether a second autoimmune condition affects MS progression has given inconsistent results.

To learn more, a group of researchers at Istanbul University in Turkey examined clinical data from 1,230 MS patients at a single treatment centre: 95 had at least one other autoimmune condition not affecting the nervous system and 1,135 did not.

Among those with a second autoimmune condition, the most common were uveitis, an inflammatory eye disease (38.9%), and Hashimoto’s disease, a thyroid condition (34.7%).

Other conditions included psoriasis (10.5%), rheumatoid arthritis (6.3%), ankylosing spondylitis (5.3%), and inflammatory bowel disease (4.2%).

The two groups were broadly similar at MS onset in terms of age, body weight, smoking status, family history of MS, and time to first treatment. But patients with a second autoimmune condition were more likely to be women (81.1% vs. 70.3%) and have a longer disease duration.

When the team examined disability levels, significantly more MS patients with a second autoimmune condition had reached a moderate level of disability – a score of 3 or more on the 10-point Expanded Disability Status Scale (EDSS) – compared to those with MS alone.

However, the proportion of patients with an EDSS score of 6 or more, indicating more severe disability, was nearly identical between the two groups.

Importantly, when researchers analysed the speed of worsening disability, there was no meaningful difference between the groups. Both reached moderate- and severe-disability milestones at the same pace.

The sole predictor of faster disability progression was the age at MS onset.

Patients diagnosed after age 35 were 1.9 times more likely to reach a moderate disability milestone and 2.7 times more likely to reach the more severe milestone compared with those diagnosed at younger ages.

‘Our study suggests that the presence of a comorbid [autoimmune disease] did not significantly alter the course of disability progression in MS,’ the researchers concluded.

‘However, comorbid autoimmunity remains a critical factor in clinical practice because it can influence treatment-related complications and overall patient management.’

Read more about symptoms and their progression in our helpful Choices booklet