HIV may lower risk for MS

HIV infection is associated with a significantly decreased risk of developing multiple sclerosis, according to new data.

Researchers said this protective effect may be the result of immunosuppression induced by HIV infection and/or ART medications, and could have implications for the treatment of multiple sclerosis (MS).

“This is the first opportunity we have had, this century, to try and identify the cause of multiple sclerosis, and possibly other autoimmune diseases,” study researcher Julian Gold, MD, FRSPH, told Infectious Disease News. “If is it proven that a retrovirus is involved, and we can repurpose HIV drugs, this will be a major advance for medicine.”

Julian Gold

The study, published in the Journal of Neurology, Neurosurgery and Psychiatry, follows the work of a Danish research team that was prompted to investigate a possible causal relationship between the two diseases after MS symptoms subsided in a patient with HIV for more than a decade after he initiated ART. They determined that HIV or its treatment may have a protective effect on the development of MS, but their study results did not achieve statistical significance.

The present study included more than 21,000 patients with HIV treated in hospitals in England between 1999 and 2011 and almost 5.3 million controls without HIV. The researchers tracked MS for 7 years in patients and compared the actual number of MS cases with the number expected to have occurred in the general population over the study period.

The researchers found that the overall rate ratio (RR) of developing MS in patients with HIV, compared with those without the infection, was 0.38 (95% CI, 0.15-0.79), based on seven actual cases and 18.3 expected cases.

The protective effect of HIV increased as more time elapsed between an HIV diagnosis and an MS diagnosis. After restricting the analysis to those patients whose first record of MS was more than 1 year after the first record of HIV, the researchers found that patients with HIV were 75% (RR=0.25; 95% CI, 0.07-0.65) less likely than those without HIV to develop MS, based on four actual cases and 15.8 expected cases. After more than 5 years, those with HIV were 85% (RR=0.15; 95% CI, <0.01-0.83) less likely to develop MS, based on one actual case and 6.7 expected cases.

The new findings were statistically significant, the researchers said. However, the study was observational and contained no information about whether patients with HIV had received ART.

They noted that there have been no documented cases of patients with coexisting MS and HIV after almost 20 years of ART.

“If subsequent studies demonstrate there is a causal protective effect of HIV and/or its treatment, and if the magnitude of it proves to be similar to our rate ratio of 0.38, this would be the largest protective effect of any factor yet observed in relation to the development of MS,” the researchers wrote.

In a related editorial, Mia van der Kop, MSc, an epidemiologist at the University of British Columbia, said the findings make a significant contribution to the literature on the relationship between HIV and MS.

“Their replication of previous findings, the magnitude of their effect size and the statistical significance of their results combine to provide further evidence to support the hypothesis that there is an association between HIV (or its treatment) and a reduced risk of MS,” she wrote. “However, additional work is required to move beyond hypothesis generation. A logical next step would be to directly examine the association between exposure to ART and the development of MS.” — John Schoen

Study researcher Julian Gold, MD, FRSPH, can be reached at Julian.gold@sesiahs.health.nsw.gov.au.

For more information:

Gold J. Neurol Neurosurg Psychiatry. 2014;doi:10.1136/jnnp-2014-307932.

van der Kop. Neurol Neurosurg Psychiatry. 2014;doi:10.1136/jnnp-2014-308297.

Disclosure: The researchers report no relevant financial disclosures.