New cohort shows the impact of hepatitis B and hepatitis C on the 'baby boom' generation

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A new US study provides more evidence of the disproportionate impact of viral hepatitis infections on the 'baby boom' generation. Writing in the online edition of Clinical Infectious Diseases, investigators from the newly established Chronic Hepatitis Cohort Study (CHeCS) reported that 75% of hepatitis C infections were among patients born between 1945 and 1964, with half of all hepatitis B infections located in the same age group.

Both infections had a significant health impact, with high rates of hospitalisation and death.

“The mortality rates and relative youth of CHeCS patients who were dying was…notable,” comment the authors.

Glossary

antiviral

A drug that acts against a virus or viruses.

biopsy

A procedure to remove a small sample of tissue so that it can be examined for signs of disease.

person years

In a study “100 person years of follow-up” could mean that information was collected on 100 people for one year, or on 50 people for two years each, or on ten people over ten years. In practice, each person’s duration of follow-up is likely to be different.

hepatitis B virus (HBV)

The hepatitis B virus can be spread through sexual contact, sharing of contaminated needles and syringes, needlestick injuries and during childbirth. Hepatitis B infection may be either short-lived and rapidly cleared in less than six months by the immune system (acute infection) or lifelong (chronic). The infection can lead to serious illnesses such as cirrhosis and liver cancer. A vaccine is available to prevent the infection.

comorbidity

The presence of one or more additional health conditions at the same time as a primary condition (such as HIV).

An estimated 3.2 million individuals in the US have chronic hepatitis C infection and another 1 million have chronic hepatitis B infection.

Neither infection has been recognised as a serious threat to public health until recently. As a result, surveillance, prevention and treatment programmes have been inadequate and poorly resourced.

Doctors wished to “assess the larger implications and impact of chronic hepatitis B and C on the US population”. They therefore established the CHeHS cohort.

The cohort involves approximately 11,000 patients who received care for either hepatitis B or C between 206 and 2008 in the cities of Detroit (Michigan), Danville (Pennsylvania), Portland (Oregon) and Honolulu (Hawaii). It is “dynamic”, meaning that new patients will be added to the cohort as they enter care.

The present study reported on the baseline demographics, liver biopsy status, hospitalisation and mortality rates with follow-up to the end of 2010.

To be eligible for inclusion in the cohort, participants had to be aged over 18 and have confirmed chronic hepatitis B or chronic hepatitis C infection.

The hepatitis B-infected cohort comprised 2202 people. They had been receiving care for a median of 5.3 years and contributed a total of 14,034 person-years of follow-up.

Approximately half were born between 1945 and 1964, with an additional 23% born between 1965 and 1974.

Most (57%) were men, 58% were Asian or Pacific Islander and13% were black. Over three-quarters (76%) had private health insurance.

Just over a fifth (22%) had undergone liver biopsy. On average, 9% of the cohort were hospitalised each year. A total of 706 participants (47%) had an undetectable viral load, and 58% of these individuals had received antiviral treatment.

By the end of 2010, 9% of participants had died. Approximately half these deaths (57%) occurred in people aged between 44 and 63 years.

The hepatitis C-infected cohort comprised 8810 participants. They had been receiving care for a median of 5.3 years.

Three-quarters of participants belong to the 'baby boom' generation and were born between 1945 and 1964. Most (60%) were men, 70% were white and 23% were black. Just under two-thirds (62%) of participants had private health insurance.

Viral load results were available for 63% of patients, and the most recent values were undetectable for a fifth of these individuals. The majority of those (80%) with an undetectable viral load had received antiviral treatment. Overall, 38% of patients had received hepatitis C therapy.

Between 2001 and 2010, 38% of hepatitis C-infected patients had a liver biopsy and 28% were tested for HIV. There was a 3% prevalence of HIV co-infection.

Approximately 13% of participants were hospitalised each year. Fourteen per cent of participants had died by the end of 2010, a mortality rate of 33 per 1000 person-years. There was an especially high mortality rate among those born during the 'baby boom' years, a quarter of whom died.

“Data from CHeCS are already yielding unique and useful information that may be used for public health action and policy development,” comment the investigators. “Our results strongly support the new policy of ‘birth cohort’ testing of those born in 1945 through 1964. This approach is likely to be more effective than the previous risk-based testing strategy in identifying persons infected with HCV in the distant past.”

They expect the cohort will “yield much data-driven information about the impact of therapies, comorbidities, and conditions on the general population with HBV and HCV in the future”.

References

Moorman AC et al. Baseline characteristics and mortality among people in care for chronic viral hepatitis: the chronic hepatitis cohort study. Clin Infect Dis, online edition. DOI: 10.1093/cid/cis815, 2012.