Hepatitis C rates in US track the opioid epidemic

Liz Highleyman
Published:
14 December 2018
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Nearly 2.4 million people in the United States are living with active hepatitis C virus (HCV) infection, according to the latest data from the US Centers for Disease Control and Prevention (CDC). Study results show that HCV prevalence is highest in states heavily impacted by the ongoing opioid epidemic.

Although direct-acting antivirals (DAAs) can cure more than 90% of people with HCV, presentations at the AASLD Liver Meeting last month in San Francisco reveal gaps in screening and treatment, especially for younger adults.

"WHO [World Health Organization] elimination goals are unattainable at current rates of linkage to HCV care in the US," Nancy Reau of Rush University Medical Center in Chicago and colleagues warned.

Estimates prior to the DAA era suggested that around 4 million people in the US were chronically infected with HCV. Since that time, hundreds of thousands of people have been successfully treated, but new infections continue to occur, especially among people who inject drugs.

The 2003-2010 National Health and Nutrition Examination Survey (NHANES), an ongoing household survey that asks participants about their health status and collects specimens for testing, found that 3.6 million people had antibodies against HCV. About 25% of people acutely infected with HCV spontaneously clear the virus without treatment.

But NHANES excludes groups known to have high HCV prevalence, including people who are incarcerated, homeless, living in long-term care facilities or members of the military, leading researchers to estimate that closer to 4.6 million people were HCV antibody positive and at least 3.5 million had active infection during this period.

The latest CDC figures show that approximately 4.1 million adults are HCV antibody positive and approximately 2.4 million – about 1% of the US adult population – are HCV RNA positive, indicating active infection. These figures are based on 2013-2016 NHANES findings along with additional data on incarcerated and homeless people, nursing home residents and those in the military.

This figure represents a decrease of around 1 million since the advent of DAAs, suggesting that the number of people achieving a cure may now exceed the number of new HCV infections.

"[C]ompared to past estimates based on similar methodology, HCV antibody prevalence may have increased, while RNA prevalence may have decreased, likely reflecting the combination of the opioid crisis, curative treatment for HCV infection, and mortality among the HCV-infected population," the study authors concluded.

The latest CDC surveillance numbers show that 2967 acute or new HCV infections were reported in 2016. However, a majority of new infections are not detected and reported, and the agency estimates that the total number is actually around 41,200.

New HCV infections are largely occurring among white young adults in non-urban areas. At The Liver Meeting, Eli Rosenberg of the University at Albany School of Public Health reported that between 2013 and 2016, three states in the Appalachian region – West Virginia, Tennessee and Kentucky – had among the highest prevalence nationwide.

Other states with above average prevalence were located in the South or West, while the Midwest and Northeast had the lowest prevalence. In terms of absolute numbers, nine states accounted for 52% of people living with active HCV infection. The states with the highest HCV rates were frequently those "deeply affected by the opioid crisis," according to the researchers.

Cascade of care

MappingHCV.com, supported by AbbVie and launched at The Liver Meeting, is a new interactive online resource featuring national US and state-­level data on HCV screening, diagnosis and treatment.

AbbVie researchers analysed two large national laboratory datasets that included more than 17 million HCV antibody tests and 1.5 million HCV RNA tests between 2013 and 2016. In line with Rosenberg's findings, this analysis showed that West Virginia and Washington, DC, had the highest overall prevalence of active HCV infection, while West Virginia and Kentucky had the highest prevalence among adults age 30 to 52 years.

Two other studies based on the same datasets, looking at the US HCV care cascade, were presented at The Liver Meeting.

Mark Sulkowski of Johns Hopkins Hospital in Baltimore and colleagues aimed to identify gaps in HCV screening and diagnosis. Traditionally, baby boomers born between 1945 and 1965 have had the highest HCV prevalence in the US, and guidelines recommend that everyone in this age group should be tested at least once. People in other age groups are advised to be screened if they are known to be at risk.

The researchers found that the number of people screened per year steadily increased from over 4 million in 2013 to over 5 million in 2016, but the proportion who were HCV antibody positive remained roughly stable (from 5.3% to 5.6%). Some states that implemented new screening policies saw large jumps, for example Connecticut (from 17 to 28 people screened per 1000 residents).

However, while the proportion of HCV antibody positive baby boomers (age 48 to 71) decreased from 9.1% to 8.1%, the proportion of positive young adults (age 18 to 39) rose from 2.8% to 3.9%. In the younger group, rates increased from 4.1% to 5.6% among men and from 2.2% to 3.0% among women.

The share of antibody positive people who received confirmatory HCV RNA testing rose dramatically, from 45.0% in 2013 to 76.5% in 2016. The researchers attributed this increase in part to wider use of 'reflex' or automatic HCV RNA testing if a blood sample tests antibody positive; people are often lost to follow-up if they have to come back for a separate confirmatory HCV RNA test.

"While rates of HCV antibody screening and confirmatory RNA testing are improving, results from this study confirm a rising HCV epidemic among young adults," the researchers concluded. "Revisions to the current recommendations for HCV antibody screening should be considered to improve detection of active HCV among younger persons for whom risk behaviours (such as injection drug use) may not be reported due to stigma."

Nancy Reau's team looked at linkage to care among people who tested HCV antibody positive.

As noted, 76.5% received confirmatory HCV RNA testing in 2016 and 63.9% were found to have active HCV infection. Of these, 17.4% saw a gastroenterologist, hepatologist or other specialist, while about 40.5% saw a primary care provider (PCP).

The proportion who saw a specialist in 2016 declined from 2013 while the proportion who saw a PCP rose – perhaps reflecting growing knowledge about DAA treatment and data showing that primary care providers can manage hepatitis C treatment with similar success.

Nonetheless, patients remained much more likely to receive treatment if they saw a specialist. Further, young adults were less likely than baby boomers to receive treatment, regardless of whether they saw a specialist  (22.6% vs 32.0% treated) or a PCP (4.5% vs 8.1%, respectively).

"Undiagnosed and untreated young adults represent a growing proportion of the chronic HCV patients and addressing gaps in care among young patients is essential to treating HCV infection," the researchers concluded. "These findings suggest that health systems need to not only redouble efforts to diagnose and treat baby boomers, but also develop additional screening efforts among younger patients." 


References

Hofmeister M et al. Estimating prevalence of hepatitis C virus infection in the United States, 20132016. Hepatology, 2018.

Rosenberg E et al. Prevalence of chronic hepatitis C virus infection, US states and District of Columbia, 2013-2016. The Liver Meeting, abstract 0088, 2018.

View the abstract.

Reau N et al. National examination of HCV linkage to care in the United States (2013­2016) based on large real­world dataset. The Liver Meeting, abstract 1567, 2018.

View the abstract.

Sulkowski M et al. National estimates for HCV screening and diagnosis rates in the United States (2013­2016) based on large real­world dataset. The Liver Meeting, abstract 1565, 2018.

View the abstract.

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