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New Drugs Could Halt U.S. Hepatitis C Epidemic, but Only with Increased Testing and Treatment

Treatment using direct-acting antiviral agents (DAAs) could have a major impact on the hepatitis C virus (HCV) epidemic in the U.S., according to a model published in the November 30 online edition of Clinical Infectious Diseases. A 4-fold increase in treatment rates could prevent over a quarter of a million HCV-related deaths by 2040, and prevalence could be reduced by 90% with the scale up of screening efforts, especially targeting people who inject drugs (PWID). But the investigators caution that elimination of the epidemic with DAAs would require near-universal testing and a 20% annual treatment rate.

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"We found that HCV prevalence, HCV-associated liver disease, and HCV-associated mortality in the United States can be substantially reduced through widespread treatment with DAAs," write the researchers. "Up to 150,000 additional cases could be identified by increasing HCV screening, effectively eliminating HCV from the non-injecting population. Further opportunities exist to greatly reduce prevalence and new infections among [people who inject drugs] through targeted screening and treatment."

An estimated 5 million individuals in the U.S. have chronic HCV infection. More than half are unaware of their status, including two-thirds of injection drug users with HCV -- the population most affected by hepatitis C.

DAAs have transformed the hepatitis C treatment, achieving cure rates in excess of 90%. The new treatments have both individual and public health benefits: reducing rates of liver-related illness and death, and also preventing HCV transmission. However, the full benefit of DAAs is likely to be compromised because of low rates of screening and treatment uptake, especially among people who inject drugs.

A team of investigators therefore developed a model to calculate the potential impact of current and enhanced levels of treatment and screening on the hepatitis C epidemic through 2040.

The model was based on epidemiological data collected between 1992 and 2014. It took into account age-related HCV prevalence and transmission mode, the impact of enhanced screening beyond current populations (CDC and U.S. Preventive Services Task Force guideline recommended the routine testing of people born between 1945 and 1965), and also expansion of treatment rates. The investigators also modeled the rates of testing and treatment required to control the epidemic among people who inject drugs.

Approximately 100,000 individuals each year currently access hepatitis C therapy. If this figure remained unchanged, there would be almost 900,000 new infections and over 800,000 HCV-related deaths by 2040. However, overall prevalence would also fall by 80%. If annual treatment increased to 200,000, 300,000, or 400,000, the 80% reduction would be achieved by 2031, 2028, or 2025, respectively.

Increasing treatment rates would also lead to significant improvements in liver-related illness and death, according to the model. Doubling treatment rates would prevent approximately 290,000 new cases of liver cirrhosis and 140,000 liver-related deaths. A 4-fold increase would avert over 500,000 new cirrhosis diagnoses and in excess of 250,000 deaths.

Without an expansion of screening, however, at least 462,000 hepatitis C cases would go untreated. Universal screening of individuals who do not inject drugs was shown to have the potential to reduce HCV prevalence to 300,000 cases. Reducing prevalence below this level would require a targeted offer of testing among people who inject drugs.

Currently, the annual screening rate in this population is a little over 4%. If unchanged, by 2040 total prevalence among people who inject drugs would fall by at most 53%, and the annual rate of new infections would fall by no more than 15%. A 90% reduction in prevalence among drug injectors would require annual screening and treatment rates of 20% and 30%, respectively.

"DAAs hold tremendous promise of improving health outcomes and reducing transmissions," conclude the authors. "Our analysis provides a forecast for the potential impact of DAAs in reducing HCV-associated liver disease, demonstrating that achievable expansion of HCV treatment at current screening rates can substantially reduce morbidity and mortality."

1/10/16

Reference

DP Durham, LA Skrip, RD Bruce, et al. DP et al. The Impact of Enhanced Screening and Treatment on Hepatitis C in the United States. Clinical Infectious Diseases. November 30, 2015 (epub ahead of print).