Different Factors Impact Spontaneous Clearance of Hepatitis C

Immune mechanisms found to have significant impact on overcoming HCV.

Among men who have sex with men and became acutely infected with hepatitis C, the virus spontaneously cleared in nearly half the cases with higher percentages among men who were noninjection drug users than men who inject drugs, according to a prospective study out of Johns Hopkins University.

Past research indicates that the probability of spontaneous clearance of the hepatitis C virus without antiviral drug treatment ranges from 11% to 49%, according to authors of the study that appears in the November 1, 2015 issue of the Oxford journal Clinical Infectious Diseases. The authors conducted a prospective study to find out what factors are associated with spontaneous clearance of the virus specifically among men who have sex with men (MSM), according to lead author Eric Seaberg, PhD, of Johns Hopkins Bloomberg School of Public Health.

The researchers used a mixture-cure model to evaluate the probability of spontaneous clearance of acute hepatitis c virus infection among 101 MSM who participated in the Multicenter AIDS Cohort Study, an ongoing observational study that was initiated in 1984 and conducted in four metropolitan areas of the country.

Data was collected at the beginning of the study and during semiannual visits and HIV status was determined at baseline and during follow-up for HIV-uninfected participants, according to the journal article.

Testing for the hepatitis C virus was conducted for participants enrolled before 2001 by use of cryopreserved serum samples obtained at enrollment and the last study visit. For men enrolled in 2001 or later, a prospective protocol was used to test for the hepatitis C virus that included retesting every 2 years for those who continued to test negative.

The study outcome was defined as spontaneous clearance of the hepatitis C virus within 2 years of infection. In order to confirm clearance in men with sufficient follow up data, there were 2 consecutive hepatitis C virus RNA positive or negative results obtained at least 6 months apart.

Researchers examined such characteristics as recruitment period, study site, race, ethnicity and age; cigarette use, alcohol and non-injection recreational drug use and injection drug use. They also looked at the number of sex partners during the previous 6 months, whether condoms were used, and HIV infection status, among other factors.

Time varying-risk factors were gathered from the last visit that took place before the hepatitis C infection was initially determined. The exceptions were drug use and sexual exposures, which were derived from combined data at visits immediately before and after hepatitis C infection to characterize risk measures during the interval in which each participant was infected with hepatitis C.

From 1984 to 2012, a total of 125 men in the cohort study became infected with the hepatitis C virus and of those 24 were excluded from Seaberg’s study analysis for lack of accurate timing and risk factor data. The journal article notes that this was the first study to examine spontaneous clearance of the hepatitis C virus prospectively in a cohort of HIV-infected and HIV-uninfected men who have sex with men with the infection acquired predominantly by sexual contact.

Seaberg and his team of researchers found that injection drug users were much less likely to clear the hepatitis C virus spontaneously. Results showed that overall hepatitis C clearance occurred in 46% of MSM, 49% in non-injection drug users and 23% in injection drug users.

“Given that nearly half of the men who acquired HCV (hepatitis C virus) through male-to-male sex spontaneously cleared the virus in this study, MSM who develop acute HCV infections should be carefully monitored for spontaneous clearance before treatment is initiated,” concluded the study authors. “Furthermore, discovering immune mechanisms that might explain an increased probability of spontaneous HCV clearance among MSM who acquired HCV through sexual contact compared with those who acquired HCV percutaneously could aid HCV vaccine development.”