March 13, 2015
A defining characteristic of hepatitis C (HCV) is the fact that a person can get re-infected with the virus if she/he is exposed to it again following cure or spontaneous clearance. Additionally, a person can experience a recurrence, or "relapse", of the virus following treatment. While this usually happens within 3-6 months from the end of treatment, it rarely occurs later.
It was with this in mind that Andrew Hill and colleagues presented a poster at CROI in Seattle entitled "Five-Year Risk of Late Relapse or Reinfection with Hepatitis C after Sustained Virologic Response: Meta-analysis of 49 Studies in 8534 Patients" (1). This review, which actually looked at 66 studies and 11,071 patients, divided patients into 3 groups: HCV mono-infected persons ("low risk"), HCV mono-infected persons who injected drugs (PWIDs) or prisoners, and HIV/HCV co-infected persons. All of the patients reviewed were treated with the dual regimen of pegylated interferon and ribavirin. They all were followed for various lengths of time, and HCV recurrence was defined as confirmed HCV RNA following an SVR of at least 6 months.
After combining the various studies, the following results were found:
|Patient Group||Number of Patients||5-Year Recurrence Rate||Rate per 100 Person Years|
|HCV Mono-Infected, low risk||9,419||1.14%||0.23 per 100 person years|
|HCV Mono-Infected, high risk||819||13.22%||2.80 per 100 person years|
|HIV/HCV Co-infected||833||21.72%||4.78 per 100 person years|
The chart shows that among low-risk, mono-infected persons, the likelihood of HCV re-infection or recurrence following SVR is very low. People who engage in higher risk activities such as injection drug use or prison (where, one can assume high risk activities such as injection drug use continue to occur in the absence of harm reduction interventions such as syringe exchange or opiate substitution therapy) are at increased risk of re-infection.
Similarly, HIV/HCV co-infected individuals are at greatest risk for re-infection. It has been established that HIV-infected persons are at greater risk of sexual transmission of HCV, and although we don't know the exact risk factors for this group, this study's findings lend support to the need for routine HCV screening for people living with HCV.
Understanding the risk of HCV re-infection is very important in helping shape the argument for providing HCV treatment in PWIDs: they are often excluded from HCV treatment under the argument of "why treat them when they are only going to get re-infected later." A 5-year recurrence rate of 13.22% is high, but more information is needed before we can jump to conclusions about PWIDs and HCV re-infection.
An understanding of access to syringe exchange or opiate substitution therapy -- two proven interventions that delay and/or reduce risk for HCV infection -- would provide us with more context for who and where the re-infection risk was greatest. Although such an analysis is beyond the scope of this poster, further research on this subject is important to help us understand how to best treat and prevent HCV in PWIDs.
HCV re-infection is an important issue in HCV care, treatment and prevention. The authors conclude that the "large differences in event rates by risk group suggest that re-infection is significantly more common than late relapse." This can provide a measure of comfort to people who are at low risk for HCV infection following treatment and the achievement of an SVR.
For people at greater risk, however, much work needs to be done. In addition to the further study of the social contexts and risk factors which may facilitate re-infection in PWIDs, people in jail or prison, and HIV/HCV co-infection, we need to increase our efforts at providing them with the tools and health education to stay HCV negative after getting cured of the virus.
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