Comorbidities Vary Among Genders in Multiple Sclerosis

Patients with multiple sclerosis (MS) have comorbidities more often than expected, and there are significant differences in the occurrence and type of comorbidity in male and female MS patients.

Ruth Ann Marrie, MD, PhD, of the University of Manitoba in Canada, and colleagues, conducted a study to investigate the prevalence of comorbidity in the MS patient population. Their work was published in Neurology, in March 2016.

The researchers stated their objective as being “To determine the prevalence of comorbidity in the multiple sclerosis (MS) population at the time of MS diagnosis," adding "We also compared the prevalence of comorbidity in the MS population to that in a matched cohort from the general population.”

The researchers used administrative health data from 4 Canadian provinces to identify 23,382 MS cases along with 116,638 controls.

The majority (71.9%) of the MS patients were female, and the most common comorbidity was depression, at 19.1% of the patients. Next was hypertension with 15.2% of the the MS patients having the condition.

The researchers add, “Among physical comorbidities, the prevalence of diabetes, hypertension, hyperlipidemia, ischemic heart disease, chronic lung disease, and epilepsy increased with age.”

Women suffered more psychiatric comorbidities, including depression, anxiety, and bipolar disorder. When compared to the matched controls, the researchers say, “all psychiatric comorbidities were more common in the MS population,” and the same was true for physical comorbidities with the exception of hyperlipidemia.

The researchers note, “For some comorbidities, the strengths of the associations differed by sex or age.” And, although hypertension was 16% higher in women with MS, it was 48% higher in men with MS. One unexpected finding was that more women than men with MS also have chronic lung disease: 39% more women with MS had the condition, whereas 21% more mne with MS did.

Overall, the researchers found “the highest rate ratios observed for physical comorbidities were seen for fibromyalgia, inflammatory bowel disease, and epilepsy.”

The differences between sexes was striking, and surprised the researchers.

“The reasons for these findings are uncertain, but sex-based differences in the association between environmental factors and disease risk are recognized,” they say. Another surprising finding was the “burden of psychiatric comorbidity for both sexes even at MS diagnosis,” according to the researchers.

Depression and anxiety are well-known risks for those with established MS, but the finding that it is often a preexisting condition is fairly new.

The researchers conclude that “comorbidity is more common than expected in MS, even around the time of diagnosis.”

They suggest that future studies should investigate the relationship of the clinical characteristics of disease progression and comorbidities.