Lower risk of multiple sclerosis (MS) in in patients with chronic hepatitis C

From the nationwide Swedish inpatient and outpatient registries
(2001 -2013) the standardized incidence ratio for developing
MS was compared between patients with and without
hepatitis C. For each patient with hepatitis up to 5 controls
were included. Controls were matched for age, sex, and place
of residence. The incidence of MS in patients with hepatitis C
was 37 of 42,522 (0.087 %) compared to 544 of 202,694 (0.27%)
in the controls. The incidence per 100,000 person years of follow
up was 36.2 compared to 13.2. The risk of developing MS
was significantly lower for both men and women.

Ref; Soderholm J et al. J Neurology 2019;266:2208-2215

Comment: There is no obvious explanation to the low incidence
of MS in hepatitis C but also with HIV-infection lower incidence
of MS has been reported. Will the possible protective
effect of HCV disappear after treatment of HCV?