Association between cytomegalovirus and MS varies by region

SEATTLE – Cytomegalovirus (CMV) seropositivity is associated with increased likelihood of multiple sclerosis (MS) in the Middle East and decreased likelihood in Europe, according to a meta-analysis presented at the annual meeting of the Consortium of Multiple Sclerosis Centers. In the United States, the association between CMV seropositivity and MS is not statistically significant, whereas combined data from all regions show a significant positive association, researchers said.

“To our knowledge, this is the largest meta-analysis evaluation of the association between CMV seropositivity and MS,” said Smathorn Thakolwiboon, MD, a neurology resident at Texas Tech University, Lubbock, and colleagues. Understanding the reasons for the geographic heterogeneity will require further research, they said.

Researchers have hypothesized that increased incidence of autoimmune conditions may be linked to the prevention or delay of common infections, but studies have been inconclusive (Neurology. 2017 Sep 26;89[13]:1330-7.).

To evaluate the association between CMV seropositivity and MS, Dr. Thakolwiboon and colleagues searched databases, including PubMed/MEDLINE, Embase, and Web of Science, from inception through Dec. 2018. They included in their analysis observational studies that evaluated the seroprevalence of CMV immunoglobulin G (IgG) in adults with MS and healthy controls. They estimated the odds ratio (OR) for CMV seropositivity and MS.

An initial search yielded 982 articles, 56 of which underwent full review. The researchers ultimately included 13 articles in their quantitative analysis. The studies included data from 3,049 patients with MS and 3,604 controls.

Overall, CMV seropositivity was significantly associated with MS (OR, 1.58; 95% confidence interval, 1.04-2.39; P = .031), but the relationship varied by region. In five U.S. studies, the association was not statistically significant (OR, 1.57; 95% CI, 0.83-2.99; P = .168). CMV seropositivity was negatively associated with MS in Europe (OR, 0.81; 95% CI, 0.68-0.96; P less than .001), but positively associated with MS in the Middle East (OR, 5.42; 95% CI, 1.06-27.89; P less than .001). “The meta-analysis showed a heterogeneity of the association between CMV seropositivity and MS,” the researchers concluded. “More genetic and environmental studies are needed for better understanding this geographic heterogeneity.”

Dr. Thakolwiboon had no disclosures. A coauthor disclosed speaking and advisory board roles with EMD Serono, Genzyme, Novartis, and Teva.

jremaly@mdedge.com

SOURCE: Thakolwiboon S et al. CMSC 2019. Abstract EPI01.