The Burden of Disease and the Evolving Landscape in Hepatitis C Therapy

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Selection from: The Burden of Disease and the Evolving Landscape in Hepatitis C

Therapy

Introduction: Prevalence and Incidence

Chronic active hepatitis C is currently a leading worldwide cause of

liver-related morbidity and mortality. Globally, 3% of the population, or 170

million people, are infected with this bloodborne infection,[1] including nearly

5 million in the United States, 85% of whom have chronic disease.[2-4]

Prevalence

Before measures were implemented to screen for the hepatitis C virus (HCV),

thousands of individuals were exposed. Initially, US estimates of HCV prevalence

were based on data obtained from the Third National Health and Nutrition

Examination Survey (NHANES III) which sampled 21,000 noninstitutionalized

civilian people between 1988 and 1994;[5] 1.8% of this population had antibodies

to HCV and 74% had detectable HCV RNA.[5] These numbers, when projected to the

entire US population, suggested that nearly 4 million individuals in the United

States were infected. These data also identified demographic, ethnic, and

geographic variations. Non-Hispanic blacks and men were most likely to have been

exposed, and 65% of all HCV antibody-positive persons were between the ages of

30 and 49 years. It is now known that this survey of the general population

severely underestimated the actual disease prevalence because it excluded

several populations with known high-risk behaviors. A survey of 1032 outpatient

veterans found that 18% had evidence of HCV exposure,[6] whereas in a screening

of homeless veterans, 40% were found to have evidence of HCV exposure.[7]

Screening in the prison systems has shown even higher rates of HCV exposure,

with a prevalence of 39% among 6536 male inmates and 54% among 977 female

inmates in the California correction system.[8] Although a current accurate

prevalence estimate does not exist, it is likely higher than the 1.8% suggested

by the NHANES data or the 1.6% estimated by a more recent 1999-2002 population

survey (Table 1).[2]

Table 1. Incidence and Prevalence of HCV Infection by Specific

Population[2,5,82,83]

Rate of New Cases of HCV/Year (Incidence)* Total Population With Anti-HCV

(Prevalence) 1994 Total Population With Anti-HCV (Prevalence) 2002 Most

Prevalent Age Range (1994) Most Prevalent Age Range (2002) Metabolic Syndrome

Prevalence

US: total general population 1992: 2.4/100,000

2005: 0.2/100,000 1.8% 1.6% 3.9% 30-39 yrs 4.3% 40-49 yrs 21.8%

Non-Hispanic whites **** 1.5% 1.5 3.2% 30-39 yrs 3.8% 40-49 yrs 23.8%

Non-Hispanic blacks **** 3.2 3.0 6.3% 40-49 yrs 9.4% 40-49 yrs 21.6%

Hispanic **** 2.1*** 1.3*** 6.0% 50-59 yrs ** 50-59 yrs in men 31.9%

Male 0.26/100,000 2.5 2.1 **40-49 yrs 24%

Female 0.21/100,000 1.2 1.1 **40-49 yrs 23.4%

*2005 unless otherwise specified

** Data presented in table form; prevalence not quantified in article

***Peak in prevalence among Mexican Americans 50-59 years may not reflect true

prevalence due to the small numbers of subjects in this age group, and also

likely explains the discrepancy between the 1994 and 2002 reports

****Incidence not quantified; article states no significant difference between

ethnicities

Incidence

After the identification of the virus in 1989 and the recognition of potential

risk factors for exposure, implementation of universal precautions, screening of

blood products, and educational and needle-exchange programs led to a dramatic

decrease in the incidence of hepatitis C. The Centers for Disease Control and

Prevention estimates that the annual incidence of acute HCV infection has

decreased from 240,000 new cases per year in the United States in the 1980s to

26,000 in 2004.[4]

This decrease in disease acquisition will unfortunately not translate to a

decrease in disease burden for decades. In most individuals, the disease is

clinically silent, remaining unrecognized for 20 years or more while significant

hepatic injury occurs, resulting in clinical manifestations. Thus, although the

prevalence of HCV infection peaked in the 1990s, the prevalence of liver disease

caused by HCV is not expected to peak until after the year 2030 and to plateau

around 2040.[9]

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