Prevalence and Challenges of Liver Diseases in Patients with Chronic Hepatitis C Virus Infection
Ira M. JAcobson; Gary L. Davis; Hashem El–Serag; Francesco Negro; Christian trépo
Posted: 11/09/2010; Clin Gastroenterol Hepatol. 2010;8(11):924-933. © 2010 AGA Institute
Abstract and Introduction
Abstract
Hepatitis C virus (HCV) infections pose a growing challenge to health care systems. Although chronic HCV infection begins as an asymptomatic condition with few short-term effects, it can progress to cirrhosis, hepatic decompensation, hepatocellular carcinoma (HCC), and death. The rate of new HCV infections is decreasing, yet the number of infected people with complications of the disease is increasing. In the United States, people born between 1945 and 1964 (baby boomers) are developing more complications of infection. Men and African Americans have a higher prevalence of HCV infection. Progression of fibrosis can be accelerated by factors such as older age, duration of HCV infection, sex, and alcohol intake. Furthermore, insulin resistance can cause hepatic steatosis and is associated with fibrosis progression and inflammation. If more effective therapies are not adopted for HCV, more than 1 million patients could develop HCV-related cirrhosis, hepatic decompensation, or HCC by 2020, which will impact the US health care system. It is important to recognize the impact of HCV on liver disease progression and apply new therapeutic strategies.
Abstract
Hepatitis C virus (HCV) infections pose a growing challenge to health care systems. Although chronic HCV infection begins as an asymptomatic condition with few short-term effects, it can progress to cirrhosis, hepatic decompensation, hepatocellular carcinoma (HCC), and death. The rate of new HCV infections is decreasing, yet the number of infected people with complications of the disease is increasing. In the United States, people born between 1945 and 1964 (baby boomers) are developing more complications of infection. Men and African Americans have a higher prevalence of HCV infection. Progression of fibrosis can be accelerated by factors such as older age, duration of HCV infection, sex, and alcohol intake. Furthermore, insulin resistance can cause hepatic steatosis and is associated with fibrosis progression and inflammation. If more effective therapies are not adopted for HCV, more than 1 million patients could develop HCV-related cirrhosis, hepatic decompensation, or HCC by 2020, which will impact the US health care system. It is important to recognize the impact of HCV on liver disease progression and apply new therapeutic strategies.
Introduction
Approximately 180 million people worldwide are infected with hepatitis C virus (HCV)[1] and are at risk of developing serious hepatic complications such as cirrhosis, hepatocellular carcinoma (HCC), or decompensation. In the United States, HCV-related end-stage liver disease is the most common indication for transplantation,[2] and HCV markers are frequently found in cases of HCC.[3,4] Although some data suggest that hepatitis C does not increase overall mortality,[5] it has been postulated that HCV infection could result in an 8- to 12-year reduction in life expectancy.[6] It is estimated that HCV caused more than 86,000 deaths in the European region in 2002.[7] The prevalence of hepatitis C–related cirrhosis and its complications is expected to continue to increase through the next decade.[8] In addition, demographic changes are expected to result in an increasing incidence of severe HCV-related liver disease as the population ages.
Approximately 180 million people worldwide are infected with hepatitis C virus (HCV)[1] and are at risk of developing serious hepatic complications such as cirrhosis, hepatocellular carcinoma (HCC), or decompensation. In the United States, HCV-related end-stage liver disease is the most common indication for transplantation,[2] and HCV markers are frequently found in cases of HCC.[3,4] Although some data suggest that hepatitis C does not increase overall mortality,[5] it has been postulated that HCV infection could result in an 8- to 12-year reduction in life expectancy.[6] It is estimated that HCV caused more than 86,000 deaths in the European region in 2002.[7] The prevalence of hepatitis C–related cirrhosis and its complications is expected to continue to increase through the next decade.[8] In addition, demographic changes are expected to result in an increasing incidence of severe HCV-related liver disease as the population ages.
Less than half (42%–46%) of patients infected with HCV genotype 1,[9,10] the major genotype in the USA,[11] achieve a sustained virologic response (SVR) with currently available treatment (peginterferon/ribavirin for 48 weeks). There is also evidence to suggest that HCV infection is both underdiagnosed and undertreated.[12–14] The lack of access to effective, welltolerated therapies has serious implications for the current and future burden of HCV. A recent report commissioned by the Institute of Medicine (IOM) of the National Academies highlighted shortcomings in care for viral hepatitis, including the estimate that up to 75% of HCV-infected persons have not even been diagnosed. The report includes sweeping recommendations for prevention, identification, control, and surveillance of HCV in the general population and identifies major gaps in services for specific populations that are disproportionately affected.[15]
In light of the public health threat posed by HCV, efforts are needed to heighten awareness of its impact on patients. Numerous extrahepatic morbidities are associated with HCV infection; these and their consequences are reviewed elsewhere.[16] Here we summarize the latest evidence for the burden of chronic hepatitis C (CHC) in the United States, focusing on hepatic complications
Evidence Acquisition
This review reflects the detailed discussion and opinions of the authors (not the meeting sponsor, Vertex Pharmaceuticals Incorporated) on key articles from the published literature at an advisory board meeting on the burden of liver disease in HCV infection held in Boston, MA, in July 2007. Before the meeting, MEDLINE searches via the PubMed interface were designed and conducted by Paula Michelle del Rosario, a professional medical writer at Gardiner-Caldwell Communications. The searches encompassed the epidemiology and/or burden as a result of HCV-related liver disease by using the Medical Subject Headings (MeSH) [hepatitis C] and either [epidemiology], or [incidence], or [prevalence], or [fibrosis AND epidemiology], or [fibrosis AND mortality], or [liver cirrhosis AND epidemiology], or [liver cirrhosis AND mortality], or [carcinoma, hepatocellular AND epidemiology], or [carcinoma, hepatocellular AND mortality], or [cholangiocarcinoma OR intrahepatic cholangiocarcinoma AND epidemiology], or [fatty liver AND epidemiology], or [fatty liver AND mortality]. Articles not published in the English language and editorials, correspondence, letters, comments, and news articles were excluded. The authors received the search terms and results of the searches in advance of the meeting, and they selected relevant articles for discussion. The authors were responsible for several additions to content and topics covered. Throughout the development of the manuscript, the authors were personally responsible for a marked expansion in the scope of the article, including new references and concepts published since the original advisory board, making this essentially a new article. In addition, the manuscript was thoroughly updated with a repeated PubMed search by Gardiner-Caldwell Communications in September 2009 to capture articles published since the original search was conducted, and relevant publications were selected for inclusion by the authors.
This review reflects the detailed discussion and opinions of the authors (not the meeting sponsor, Vertex Pharmaceuticals Incorporated) on key articles from the published literature at an advisory board meeting on the burden of liver disease in HCV infection held in Boston, MA, in July 2007. Before the meeting, MEDLINE searches via the PubMed interface were designed and conducted by Paula Michelle del Rosario, a professional medical writer at Gardiner-Caldwell Communications. The searches encompassed the epidemiology and/or burden as a result of HCV-related liver disease by using the Medical Subject Headings (MeSH) [hepatitis C] and either [epidemiology], or [incidence], or [prevalence], or [fibrosis AND epidemiology], or [fibrosis AND mortality], or [liver cirrhosis AND epidemiology], or [liver cirrhosis AND mortality], or [carcinoma, hepatocellular AND epidemiology], or [carcinoma, hepatocellular AND mortality], or [cholangiocarcinoma OR intrahepatic cholangiocarcinoma AND epidemiology], or [fatty liver AND epidemiology], or [fatty liver AND mortality]. Articles not published in the English language and editorials, correspondence, letters, comments, and news articles were excluded. The authors received the search terms and results of the searches in advance of the meeting, and they selected relevant articles for discussion. The authors were responsible for several additions to content and topics covered. Throughout the development of the manuscript, the authors were personally responsible for a marked expansion in the scope of the article, including new references and concepts published since the original advisory board, making this essentially a new article. In addition, the manuscript was thoroughly updated with a repeated PubMed search by Gardiner-Caldwell Communications in September 2009 to capture articles published since the original search was conducted, and relevant publications were selected for inclusion by the authors.
Prevalence, Identification of at-risk Individuals, and Effects on Life Expectancy
Various estimates of HCV prevalence in the US population place the number of infected individuals (as defined by anti-HCV antibody positivity) at between 4.1 and 5 million. Of these, 3.2–3.4 million are chronically infected.[17,18] During the first 10–20 years of infection HCV-infected individuals generally experience asymptomatic or mild illness,[19] which explains why an estimated 75% of infections remain undiagnosed in the United States.[15,20] Despite a decline in the number of new US cases of HCV infection from a peak of an estimated 262,000/year in 1986 to 17,000/year in 2007,[21] the prevalence of individuals infected with HCV for more than 20 years is expected to continue to increase until 2015.[22] In the National Health and Nutrition Examination Survey (NHANES; 1999–2002), patients aged 40–49 years accounted for 66% of American HCVinfected patients, and the prevalence of HCV infection in the United States was 2.7 times higher among 40- to 49-year-olds than the general population (Figure 1).[17] This "baby boomer" generation is particularly susceptible to blood-borne HCV transmission as a result of an increased lifetime risk of injection drug use (IDU), blood transfusion before 1992, or sexual activity with ≥20 partners, compared with older or younger patients.[23,24] The prevalence of HCV infection varies by age, sex, and race/ethnicity, and early identification of at-risk individuals through routine questioning by clinicians is critical, because management options are limited in late-stage disease.[24]
Various estimates of HCV prevalence in the US population place the number of infected individuals (as defined by anti-HCV antibody positivity) at between 4.1 and 5 million. Of these, 3.2–3.4 million are chronically infected.[17,18] During the first 10–20 years of infection HCV-infected individuals generally experience asymptomatic or mild illness,[19] which explains why an estimated 75% of infections remain undiagnosed in the United States.[15,20] Despite a decline in the number of new US cases of HCV infection from a peak of an estimated 262,000/year in 1986 to 17,000/year in 2007,[21] the prevalence of individuals infected with HCV for more than 20 years is expected to continue to increase until 2015.[22] In the National Health and Nutrition Examination Survey (NHANES; 1999–2002), patients aged 40–49 years accounted for 66% of American HCVinfected patients, and the prevalence of HCV infection in the United States was 2.7 times higher among 40- to 49-year-olds than the general population (Figure 1).[17] This "baby boomer" generation is particularly susceptible to blood-borne HCV transmission as a result of an increased lifetime risk of injection drug use (IDU), blood transfusion before 1992, or sexual activity with ≥20 partners, compared with older or younger patients.[23,24] The prevalence of HCV infection varies by age, sex, and race/ethnicity, and early identification of at-risk individuals through routine questioning by clinicians is critical, because management options are limited in late-stage disease.[24]
Figure 1.
Prevalence of HCV antibodies by age group (A) and year of birth (B) in the 1988–1994 and 1999–2002 NHANES. Vertical bars, 95% confidence intervals. Adapted with permission from Armstrong et al 2006.17
After 30 years of infection, an estimated 15%–35% of patients will develop cirrhosis (5-year survival, 75%–80%);[6] after 40 years, up to 60% could have cirrhosis.
After 30 years of infection, an estimated 15%–35% of patients will develop cirrhosis (5-year survival, 75%–80%);[6] after 40 years, up to 60% could have cirrhosis.
Given the high prevalence of HCV infection among 40- to 49-year-olds[17] and that Americans are now expected to live into their mid-70s or beyond, the incidence of complications of HCV infections can be expected to further increase in coming years. In fact, from 1995–2004, US HCV-related mortality already increased 123% from 1.09/100,000 to 2.44/100,000 persons, although this study has some limitations.[25] Furthermore, the proportion of CHC patients in the United States with cirrhosis is projected to rise from 25% in 2010 to 45% in 2030.[8] Projections also estimate that without effective treatment, the annual number of US patients with cirrhosis, hepatic decompensation, or HCC will roughly double by 2020, and liver-related deaths will almost triple (Table 1).[26] Although not all data agree with these estimates,[5] several studies have suggested that HCV infection could have a deleterious effect on population mortality rates and life expectancy.[27,28] HCV increased the risk of death in several analyses, irrespective of comorbidities such as coinfection with human immunodeficiency virus (HIV)[29] or hepatitis B virus (HBV)[30,31] and even after adjustment for alcohol consumption.[32] Furthermore, numerous studies[33–37] and a Cochrane review[38] indicated that achievement of an SVR through effective antiviral therapy can significantly reduce mortality in patients with chronic HCV. If all HCV-infected patients were treated with currently available treatment in 2010, liver-related HCV-associated deaths could be reduced by 36% by 2020,[8] whereas antiviral treatment rates are currently declining. Improvements in diagnosis and treatment are therefore necessary to reduce the associated public health burden.[15,39]
Hepatic Consequences
Individuals with CHC are at increased risk of liverrelated morbidity and mortality. HCV infection was associated with 27% of all US liver transplants performed in 2007,[2] and US-based studies demonstrated that up to 51%–55% of HCC patients have anti-HCV antibodies.[3,4] There is also a link between steatosis and liver fibrosis in HCV-infected patients,[40] as well as a potential association between HCV infection and HCC or, as described more recently, of intrahepatic cholangiocarcinoma (ICC).[41–45] In some ethnic groups such as Latinos the course of HCV infection is more aggressive, with a higher risk of cirrhosis than other ethnic groups.[46] Furthermore, disease progression is more rapid in patients who are coinfected with HCV and HIV. Coinfected patients have approximately double the risk of cirrhosis or decompensation than those infected with HCV alone.[47]
Fibrosis and Cirrhosis
Progressive hepatic fibrosis leading to cirrhosis is the major complication of chronic HCV infection and accounts for almost all HCV-related morbidity and mortality.[26] Early studies suggested little, if any, fibrosis progression during the first decade of infection, followed by a slow, regular progression during the next 15 years, increasing to an intermediate rate during the subsequent decade.[48,49] In a German cohort study of 1833 women infected with HCV-contaminated immunoglobulin, 0.5% of patients developed cirrhosis after 25 years.[50] Similarly, in a study of 376 HCV-infected women conducted by the Irish Hepatology Research Group, 51% of patients had fibrosis after 17 years, but only 2% had probable/definite cirrhosis.[51] These estimates of cirrhosis rates are considerably lower than those from the US multicohort study[8] and the widely cited US military study (approximately 35%).[5] Fibrosis outcomes of 184 women from the same cohort were followed up for the subsequent 5 years; 49% showed no change in fibrosis, 24% showed regression, and 27% showed progression.[52]
Recent data reinforce the potential for severe liver disease to develop in some patients. Among 485 plasma donors infected during the early 1970s, 34% had stage F3/F4 fibrosis (bridging fibrosis), cirrhosis, or HCC after 31 years; their 35-year cumulative survival was 84% versus 91%–95% for the general population.[53] Similarly, a study of 300 black and white Americans with untreated HCV infection found that 29% of patients had stage F3/F4 fibrosis after 20 years, and 4.7% had confirmed cirrhosis.[54] It should be noted, however, that these studies could have selected patients with severe disease.
The nonlinear progression of fibrosis was recently confirmed in a meta-analysis of 111 HCV studies.[55] The mean annual stage-specific transition probabilities were 0.117 for stage F0 to F1, 0.085 for F1 to F2, 0.120 for F2 to F3, and 0.116 for F3 to F4. Although the estimated prevalence of cirrhosis was 16% after 20 years, there was wide variation between studies, suggesting that fibrosis is a highly unpredictable process.
Infection duration is a major risk factor for severe fibrosis,[55] with the progression rate in a 50-year-old being almost 3 times that in a 20-year-old.[56] Age at time of infection is also important. In a biopsy analysis of 247 treatment-naïve HCV patients, progression rates were 0.13, 0.14, 0.27, and 0.36 fibrosis units/year for patients aged ≤19, 20–24, 25–36, and >36 years at infection, respectively.[57] Age >36 years (vs ≤36 years) at time of infection was independently associated with faster progression. Men infected before age 50 have been identified as comprising the majority of cases of cirrhosis today (73.6%), whereas men aged >50 years when infected have faster disease progression compared with other age groups.[8]
Several other factors, including sex, baseline fibrosis, HCV genotype, HIV/HBV coinfection, and alcohol consumption, also influence fibrosis progression (Table 2).[54–69] Identifying these factors can be useful when determining prognosis and advising patients on minimizing liver damage. Indeed, a recent study suggested that HCV genotype 3 might pose a particularly high risk of progressive fibrosis.[69] Insulin resistance has been linked with fibrosis,[70,71] and several studies have reported that this relationship remains significant, irrespective of HCV genotype.[62,72,73] In addition, serum aminotransferase level elevations and the degree of hepatocellular necrosis/inflammation on biopsy have been found to predict fibrosis progression.[74] Genetic factors might also play a role in fibrosis progression.[75,76] Recent data indicate that the cirrhosis risk score, which is based on the association of 7 host genes, might help to differentiate HCV patients at high versus low risk of progressing toward cirrhosis, including those with early or mild CHC.[76–78] Steatosis has also been linked to fibrosis progression,[40,67,79] as has regular cannabis use.[68,80] There is evidence of an association between cigarette smoking and hepatitis fibrosis,[81] but not all studies have verified such an association.[82]
Hepatocellular Carcinoma
The greatest increase in US cancer deaths from 1995–2004 was in those caused by cancers of the liver and bile duct, of which HCC comprised about 76%.[83] This might be attributed to the increasing incidence of HCV-related HCC because rates for HBVrelated and alcohol-related HCC have remained stable during recent years.[84,85] The incidence of HCV-related HCC in the United States is projected to peak in 2019 at 14,000 cases/year.[8] In a large US database, the proportion of HCV-related cases of HCC among HCC patients aged ≥65 years doubled from 11% in 1993–1996 to 21% in 1996–1999.[84] During the past decade, the fastest increase in HCC incidence has affected Hispanics and whites.[86] In multivariate analysis HCV infection was an independent predictor for the development of HCC.[87] Furthermore, maintenance therapy with peginterferon did not reduce the 5-year incidence of HCC in the HALT-C cohort.[88]
Comparisons of US and Japanese HCV strains suggest that the US HCV epidemic began about 2 to 3 decades after that in Japan.[89,90] This has led to speculation that the burden of HCC in the United States might eventually equal that currently seen in Japan as HCV-infected individuals age and their infection duration increases. In Japan, HCV-related HCC accounts for 80% of all HCC cases,[91] and the rate of HCC among HCV-infected men has risen from 17.4/100,000 in 1972–1976 (32,335 deaths) to 27.4/100,000 in 1992–1996 (109,365 deaths).[92]
A recent Italian study of 214 HCV-infected patients with Child–Pugh class A cirrhosis showed that HCC developed at a rate of almost 4%/year.[93] HCC was the first complication to occur in 55 (27%) patients; after 17 years, HCC had developed in 68 (32%) patients.[93] In another cohort of 416 patients with uncomplicated Child–Pugh class A HCV-related cirrhosis, the incidence of HCC was 13.4% at 5 years, and the 5-year HCC death rate was 15.3%, with the hazard rate of HCC tending to increase over time.[94]
Several factors influence the risk of HCC in patients with HCV-related cirrhosis. Generally, HCC risk is increased in patients aged >50 years or those infected when aged >50 years, patients with longer duration of infection, men, overweight or diabetic patients, and patients with advanced cirrhosis or elevated alpha-fetoprotein.[8,95,96] Other possible risk factors include the presence of steatosis,[41] HCV genotype 1b,[97] Asian/African American race,[98] and occult HBV infection.[99] As for hepatic fibrosis, an association between cigarette smoking and HCV-related HCC has been suggested in some studies[100] but not others.[101]
Chronic HCV-related inflammation might increase HCC risk by shifting hepatocytic transforming growth factor– beta signaling from tumor suppression to fibrogenesis.[102] HCC generally develops after cirrhosis is established, signifying the likely importance of long-standing necrosis and regeneration, an environment of extensive scarring, in its pathogenesis. HCV might influence hepatocarcinogenesis through the oncogenic effects of its core protein, which might augment oxidative stress.[103] It might also alter the signaling cascade of mitogen-activated protein kinase and activating factor 1, thereby activating cellcycle control. Liver angiogenesis and the neovascular response,[104,105] plus genomic changes that deregulate components of the Jak/STAT pathway in early carcinogenesis,[106] might also promote HCV-related hepatocarcinogenesis. Additional mechanisms have also been proposed.[107]
Cholangiocarcinoma
Various small studies have demonstrated a link between HCV and ICC.[42–45] A recent large cohort study of >140,000 HCV-infected military veterans[108] showed a >2-fold increase in ICC risk in HCV-infected patients versus noninfected controls. However, many of these hospital-based, case-control studies are limited by the potential for selection or ascertainment bias,[108] and some studies have failed to observe any association between HCV and ICC.[109,110] The association of HCV infection with susceptibility to ICC, and the pathogenetic basis for such an association, warrant further investigation. Chronic HCV infection was not a risk for extrahepatic cholangiocarcinoma (ECC).[111]
Decompensation
Patients with HCV-associated cirrhosis are at high risk of developing hepatic decompensation, manifesting as hepatic synthetic dysfunction or complications of portal hypertension. Clinical signs of decompensation include ascites, encephalopathy, and upper gastrointestinal hemorrhage caused by variceal bleeding.[93,112]
Hepatic Consequences
Individuals with CHC are at increased risk of liverrelated morbidity and mortality. HCV infection was associated with 27% of all US liver transplants performed in 2007,[2] and US-based studies demonstrated that up to 51%–55% of HCC patients have anti-HCV antibodies.[3,4] There is also a link between steatosis and liver fibrosis in HCV-infected patients,[40] as well as a potential association between HCV infection and HCC or, as described more recently, of intrahepatic cholangiocarcinoma (ICC).[41–45] In some ethnic groups such as Latinos the course of HCV infection is more aggressive, with a higher risk of cirrhosis than other ethnic groups.[46] Furthermore, disease progression is more rapid in patients who are coinfected with HCV and HIV. Coinfected patients have approximately double the risk of cirrhosis or decompensation than those infected with HCV alone.[47]
Fibrosis and Cirrhosis
Progressive hepatic fibrosis leading to cirrhosis is the major complication of chronic HCV infection and accounts for almost all HCV-related morbidity and mortality.[26] Early studies suggested little, if any, fibrosis progression during the first decade of infection, followed by a slow, regular progression during the next 15 years, increasing to an intermediate rate during the subsequent decade.[48,49] In a German cohort study of 1833 women infected with HCV-contaminated immunoglobulin, 0.5% of patients developed cirrhosis after 25 years.[50] Similarly, in a study of 376 HCV-infected women conducted by the Irish Hepatology Research Group, 51% of patients had fibrosis after 17 years, but only 2% had probable/definite cirrhosis.[51] These estimates of cirrhosis rates are considerably lower than those from the US multicohort study[8] and the widely cited US military study (approximately 35%).[5] Fibrosis outcomes of 184 women from the same cohort were followed up for the subsequent 5 years; 49% showed no change in fibrosis, 24% showed regression, and 27% showed progression.[52]
Recent data reinforce the potential for severe liver disease to develop in some patients. Among 485 plasma donors infected during the early 1970s, 34% had stage F3/F4 fibrosis (bridging fibrosis), cirrhosis, or HCC after 31 years; their 35-year cumulative survival was 84% versus 91%–95% for the general population.[53] Similarly, a study of 300 black and white Americans with untreated HCV infection found that 29% of patients had stage F3/F4 fibrosis after 20 years, and 4.7% had confirmed cirrhosis.[54] It should be noted, however, that these studies could have selected patients with severe disease.
The nonlinear progression of fibrosis was recently confirmed in a meta-analysis of 111 HCV studies.[55] The mean annual stage-specific transition probabilities were 0.117 for stage F0 to F1, 0.085 for F1 to F2, 0.120 for F2 to F3, and 0.116 for F3 to F4. Although the estimated prevalence of cirrhosis was 16% after 20 years, there was wide variation between studies, suggesting that fibrosis is a highly unpredictable process.
Infection duration is a major risk factor for severe fibrosis,[55] with the progression rate in a 50-year-old being almost 3 times that in a 20-year-old.[56] Age at time of infection is also important. In a biopsy analysis of 247 treatment-naïve HCV patients, progression rates were 0.13, 0.14, 0.27, and 0.36 fibrosis units/year for patients aged ≤19, 20–24, 25–36, and >36 years at infection, respectively.[57] Age >36 years (vs ≤36 years) at time of infection was independently associated with faster progression. Men infected before age 50 have been identified as comprising the majority of cases of cirrhosis today (73.6%), whereas men aged >50 years when infected have faster disease progression compared with other age groups.[8]
Several other factors, including sex, baseline fibrosis, HCV genotype, HIV/HBV coinfection, and alcohol consumption, also influence fibrosis progression (Table 2).[54–69] Identifying these factors can be useful when determining prognosis and advising patients on minimizing liver damage. Indeed, a recent study suggested that HCV genotype 3 might pose a particularly high risk of progressive fibrosis.[69] Insulin resistance has been linked with fibrosis,[70,71] and several studies have reported that this relationship remains significant, irrespective of HCV genotype.[62,72,73] In addition, serum aminotransferase level elevations and the degree of hepatocellular necrosis/inflammation on biopsy have been found to predict fibrosis progression.[74] Genetic factors might also play a role in fibrosis progression.[75,76] Recent data indicate that the cirrhosis risk score, which is based on the association of 7 host genes, might help to differentiate HCV patients at high versus low risk of progressing toward cirrhosis, including those with early or mild CHC.[76–78] Steatosis has also been linked to fibrosis progression,[40,67,79] as has regular cannabis use.[68,80] There is evidence of an association between cigarette smoking and hepatitis fibrosis,[81] but not all studies have verified such an association.[82]
Hepatocellular Carcinoma
The greatest increase in US cancer deaths from 1995–2004 was in those caused by cancers of the liver and bile duct, of which HCC comprised about 76%.[83] This might be attributed to the increasing incidence of HCV-related HCC because rates for HBVrelated and alcohol-related HCC have remained stable during recent years.[84,85] The incidence of HCV-related HCC in the United States is projected to peak in 2019 at 14,000 cases/year.[8] In a large US database, the proportion of HCV-related cases of HCC among HCC patients aged ≥65 years doubled from 11% in 1993–1996 to 21% in 1996–1999.[84] During the past decade, the fastest increase in HCC incidence has affected Hispanics and whites.[86] In multivariate analysis HCV infection was an independent predictor for the development of HCC.[87] Furthermore, maintenance therapy with peginterferon did not reduce the 5-year incidence of HCC in the HALT-C cohort.[88]
Comparisons of US and Japanese HCV strains suggest that the US HCV epidemic began about 2 to 3 decades after that in Japan.[89,90] This has led to speculation that the burden of HCC in the United States might eventually equal that currently seen in Japan as HCV-infected individuals age and their infection duration increases. In Japan, HCV-related HCC accounts for 80% of all HCC cases,[91] and the rate of HCC among HCV-infected men has risen from 17.4/100,000 in 1972–1976 (32,335 deaths) to 27.4/100,000 in 1992–1996 (109,365 deaths).[92]
A recent Italian study of 214 HCV-infected patients with Child–Pugh class A cirrhosis showed that HCC developed at a rate of almost 4%/year.[93] HCC was the first complication to occur in 55 (27%) patients; after 17 years, HCC had developed in 68 (32%) patients.[93] In another cohort of 416 patients with uncomplicated Child–Pugh class A HCV-related cirrhosis, the incidence of HCC was 13.4% at 5 years, and the 5-year HCC death rate was 15.3%, with the hazard rate of HCC tending to increase over time.[94]
Several factors influence the risk of HCC in patients with HCV-related cirrhosis. Generally, HCC risk is increased in patients aged >50 years or those infected when aged >50 years, patients with longer duration of infection, men, overweight or diabetic patients, and patients with advanced cirrhosis or elevated alpha-fetoprotein.[8,95,96] Other possible risk factors include the presence of steatosis,[41] HCV genotype 1b,[97] Asian/African American race,[98] and occult HBV infection.[99] As for hepatic fibrosis, an association between cigarette smoking and HCV-related HCC has been suggested in some studies[100] but not others.[101]
Chronic HCV-related inflammation might increase HCC risk by shifting hepatocytic transforming growth factor– beta signaling from tumor suppression to fibrogenesis.[102] HCC generally develops after cirrhosis is established, signifying the likely importance of long-standing necrosis and regeneration, an environment of extensive scarring, in its pathogenesis. HCV might influence hepatocarcinogenesis through the oncogenic effects of its core protein, which might augment oxidative stress.[103] It might also alter the signaling cascade of mitogen-activated protein kinase and activating factor 1, thereby activating cellcycle control. Liver angiogenesis and the neovascular response,[104,105] plus genomic changes that deregulate components of the Jak/STAT pathway in early carcinogenesis,[106] might also promote HCV-related hepatocarcinogenesis. Additional mechanisms have also been proposed.[107]
Cholangiocarcinoma
Various small studies have demonstrated a link between HCV and ICC.[42–45] A recent large cohort study of >140,000 HCV-infected military veterans[108] showed a >2-fold increase in ICC risk in HCV-infected patients versus noninfected controls. However, many of these hospital-based, case-control studies are limited by the potential for selection or ascertainment bias,[108] and some studies have failed to observe any association between HCV and ICC.[109,110] The association of HCV infection with susceptibility to ICC, and the pathogenetic basis for such an association, warrant further investigation. Chronic HCV infection was not a risk for extrahepatic cholangiocarcinoma (ECC).[111]
Decompensation
Patients with HCV-associated cirrhosis are at high risk of developing hepatic decompensation, manifesting as hepatic synthetic dysfunction or complications of portal hypertension. Clinical signs of decompensation include ascites, encephalopathy, and upper gastrointestinal hemorrhage caused by variceal bleeding.[93,112]
In an analysis of data from 1000 HCV patients with mild to advanced fibrosis, the incidence of decompensated cirrhosis after 5–7 years of follow-up was 43.5/10,000 person-years or about 1 in 230 patients/year.[65] Similarly, a retrospective study reported the 5-year risk of decompensation to be 18% in 384 HCV patients with compensated cirrhosis (incidence, 3.9%/year),[112] and a recent estimate suggests decompensation is currently present in 11.7% of CHC patients with cirrhosis.[8] Decompensation has become more common since 1995, and because the proportion of CHC patients with cirrhosis is expected to increase through 2030, the incidence of decompensation can be expected to increase accordingly.[8] It should be noted, however, that this model estimates that the majority of cirrhotic patients with chronic HCV infection will not develop decompensation during the first 3 decades of infection. Annual incidence rates for ascites (2.9%), jaundice (2.0%), upper gastrointestinal bleeding (0.7%), and encephalopathy (0.1%) were established in a later prospective study of 214 HCV-RNA seropositive patients after 114 months of follow-up.[93]
Age at HCV acquisition is relevant, with decompensation risk as high as 133/10,000 person-years in patients infected after 39 years of age.[65] In addition, the presence of the human leukocyte antigen DRB1*1201–3 allele might be associated with a higher rate of progression toward decompensated cirrhosis and HCC.[65] The identification of reliable proteomic/genomic markers for risk of advanced HCV-related liver disease would aid prognostication and therapeutic decision-making.
Steatosis
Steatosis occurs to some degree in about half of all patients with chronic HCV infection.[40,113] In a meta-analysis of data from >3000 patients, steatosis was independently associated with the presence of fibrosis, diabetes, hepatic inflammation, ongoing alcohol abuse, overweight (body mass index >25), age ≥45 years, and genotype 3 infection.[40] Among 101 HCV-infected patients with no factors predisposing to fatty liver, steatosis was found in 41% of patients, irrespective of sex, age, or infection route.[114]
Steatosis occurs to some degree in about half of all patients with chronic HCV infection.[40,113] In a meta-analysis of data from >3000 patients, steatosis was independently associated with the presence of fibrosis, diabetes, hepatic inflammation, ongoing alcohol abuse, overweight (body mass index >25), age ≥45 years, and genotype 3 infection.[40] Among 101 HCV-infected patients with no factors predisposing to fatty liver, steatosis was found in 41% of patients, irrespective of sex, age, or infection route.[114]
Two main mechanisms underlie the pathogenesis of steatosis in HCV-infected patients who abstain from alcohol, a direct viral effect and a metabolic mechanism. Viral steatosis is associated with genotype 3 HCV infection,[40,114–117] where the severity of steatosis correlates with serum[71,115] and intrahepatic[113] viral load. This type of steatosis often resolves after viral eradication.[116–118] It is believed that HCV genotype 3 has a direct effect on hepatocyte lipid metabolism, resulting in fat accumulation. Interactions involving the HCV genotype 3 core protein, such as enhanced fatty acid synthase promoter activation[119] and increased lipid affinity,[120] are being investigated in vitro.
Metabolic steatosis is seen primarily in patients infected with genotype non-3 HCV[40,72] and is largely due to insulin resistance,[62,72,121] characterized by hyperinsulinemia and free fatty acid overflow to organs and non-adipose tissues.[122] These alterations give rise to triglyceride accumulation in hepatocytes, resulting in steatosis.[40,70,71,123]
Steatosis might reduce the likelihood of achieving SVR with HCV treatment, even when other steatosis-inducing factors are accounted for. In one study, SVR rates were 18%–32% lower in people with steatosis versus those without steatosis after adjusting for other potentially confounding cofactors such as genotype, fibrosis score, and viral load.[117]
Reducing the Impact of Infection
About 85% of HCV-positive persons in the United States general population can be identified on the basis of 3 characteristics: IDU history, blood transfusion before 1992, or abnormal serum alanine transaminase levels.[17] In selected populations, other characteristics might also be useful for screening. A retrospective study of 5400 US veterans found that the following factors predicted HCV infection: IDU, blood transfusion before 1992, service during the Vietnam war, tattoo, and a history of abnormal liver test results.[123] However, HCV risk factor histories are rarely documented in clinical practice.[124] Infected patients can thus remain undiagnosed until they present with hepatic complications. Recent guidelines issued by the American Association for the Study of Liver Diseases (AASLD) make recommendations for diagnosis and counseling of HCV-infected patients on alcohol, weight loss, and treatment to prevent the development of cirrhosis and other complications.[125]
About 85% of HCV-positive persons in the United States general population can be identified on the basis of 3 characteristics: IDU history, blood transfusion before 1992, or abnormal serum alanine transaminase levels.[17] In selected populations, other characteristics might also be useful for screening. A retrospective study of 5400 US veterans found that the following factors predicted HCV infection: IDU, blood transfusion before 1992, service during the Vietnam war, tattoo, and a history of abnormal liver test results.[123] However, HCV risk factor histories are rarely documented in clinical practice.[124] Infected patients can thus remain undiagnosed until they present with hepatic complications. Recent guidelines issued by the American Association for the Study of Liver Diseases (AASLD) make recommendations for diagnosis and counseling of HCV-infected patients on alcohol, weight loss, and treatment to prevent the development of cirrhosis and other complications.[125]
Diagnosis and Screening
Figure 2 summarizes the clinical management of patients at risk of HCV infection. Asking patients about their transfusion history and high-risk drug/sexual behavior during health care visits should be routine, and high-risk patients (history of IDU, blood transfusion before 1992, or HIV-positive) should be tested, with cognizance of the higher prevalence rates in men, "baby boomers," and African Americans. The AASLD guidelines promote screening in at-risk populations to reduce HCV transmission rates.[125] The recent IOM report on viral hepatitis includes a recommendation that federally funded US health care insurers improve access to HCV screening as part of preventative care for the general population, so people at risk of HCV infection can be identified.[15]
Figure 2 summarizes the clinical management of patients at risk of HCV infection. Asking patients about their transfusion history and high-risk drug/sexual behavior during health care visits should be routine, and high-risk patients (history of IDU, blood transfusion before 1992, or HIV-positive) should be tested, with cognizance of the higher prevalence rates in men, "baby boomers," and African Americans. The AASLD guidelines promote screening in at-risk populations to reduce HCV transmission rates.[125] The recent IOM report on viral hepatitis includes a recommendation that federally funded US health care insurers improve access to HCV screening as part of preventative care for the general population, so people at risk of HCV infection can be identified.[15]
Figure 2.
Summary of the screening, diagnosis, and treatment of patients at risk of HCV infection
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Once diagnosed, patients should be evaluated for HCV RNA, genotype, and serologic exclusion of common liver diseases. Baseline imaging (ultrasound) might also be useful. Assessing fibrosis by liver biopsy can be used to estimate prognosis, treatment urgency, and necessity of HCC screening. Surrogate methods, including serum fibrosis markers, imaging techniques, and indirect methods to measure liver stiffness such as transient elastography,[125] might have a future role.
Because insulin resistance enhances fibrosis progression, monitoring insulin resistance, fasting glucose, or insulin levels is advisable. In addition, lifestyle modifications, including weight loss and dietary changes, might reduce insulin resistance and slow the fibrosis rate. All patients should be assessed for immunity against hepatitis A/B by assessment of disease markers and vaccinated if seronegative.[125] Counseling should be offered regarding alcohol consumption, if appropriate.
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Treatment
Currently, the only drugs available to treat HCV are peginterferon and ribavirin. SVR rates associated with peginterferon/ribavirin are suboptimal, particularly for genotype 1–infected patients.[9,10] The AASLD guidelines recommend an individualized treatment approach based on assessment of comorbidities, likelihood of response, and side-effect potential.[125] Although more effective options are needed, successful treatment can eradicate the virus and thereby minimize complications and possibly improve mortality rates.[126,127] Nearly all patients (99.2%) maintain undetectable HCV loads 5 years after attaining SVR, representing a "virologic cure."[126] Some patients with fibrosis who achieve SVR demonstrate an improvement in necroinflammatory activity and fibrosis regression.[128 –130] Furthermore, the 5-year survival of SVR patients is similar to that of the overall population.[130] The role of interferon in preventing HCC is controversial. A reduced risk of HCC has been noted in patients achieving SVR; however, reports of HCC after SVR was achieved in cirrhotic patients indicate a need for surveillance and reinforce the importance of viral eradication before cirrhosis develops.[131,132] Long-term maintenance therapy with peginterferon does not appear to affect the incidence of HCC.[133]
Currently, the only drugs available to treat HCV are peginterferon and ribavirin. SVR rates associated with peginterferon/ribavirin are suboptimal, particularly for genotype 1–infected patients.[9,10] The AASLD guidelines recommend an individualized treatment approach based on assessment of comorbidities, likelihood of response, and side-effect potential.[125] Although more effective options are needed, successful treatment can eradicate the virus and thereby minimize complications and possibly improve mortality rates.[126,127] Nearly all patients (99.2%) maintain undetectable HCV loads 5 years after attaining SVR, representing a "virologic cure."[126] Some patients with fibrosis who achieve SVR demonstrate an improvement in necroinflammatory activity and fibrosis regression.[128 –130] Furthermore, the 5-year survival of SVR patients is similar to that of the overall population.[130] The role of interferon in preventing HCC is controversial. A reduced risk of HCC has been noted in patients achieving SVR; however, reports of HCC after SVR was achieved in cirrhotic patients indicate a need for surveillance and reinforce the importance of viral eradication before cirrhosis develops.[131,132] Long-term maintenance therapy with peginterferon does not appear to affect the incidence of HCC.[133]
Davis et al[8] extended their multicohort model to include an assessment of treatment effects, predicting that an increase in the proportion of treated patients (or use of treatment with improved viral clearance rate) would result in reduced rates of cirrhosis, liver failure, HCC, and liver-related death.
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Education and Counseling
A lack of knowledge about HCV among health care providers, social service providers, and the public is identified by the IOM as a major challenge to controlling the disease. Education and outreach programs for these audiences feature among the recent IOM recommendations for comprehensive viral hepatitis services aimed at preventing viral transmission, missed diagnosis, and poor health outcomes in HCV.[15]
A lack of knowledge about HCV among health care providers, social service providers, and the public is identified by the IOM as a major challenge to controlling the disease. Education and outreach programs for these audiences feature among the recent IOM recommendations for comprehensive viral hepatitis services aimed at preventing viral transmission, missed diagnosis, and poor health outcomes in HCV.[15]
Increasing access to treatment and providing support to optimize therapeutic adherence might help to improve outcomes. This requires a greater emphasis on early detection along with careful, individualized diagnostic assessment and therapeutic decision-making. Many physicians have adopted a "watch-and-wait" approach, particularly for patients with minimal liver disease. Although this might sometimes be appropriate, patients should be advised of the possibility of unexpectedly rapid disease progression and the need for regular follow-up, including repeat biopsies every 3–5 years. The pros and cons of deferring therapy should be discussed in the context of the patient's clinical and histologic profile.
Many eligible patients decline antiviral treatment. In a study of 280 US patients, 41% declined treatment, citing no symptoms and concerns about side effects.[134] Information provided by health care providers is critical; in 3 US cities, interest in HCV treatment among injection drug users was 7-fold higher among patients who were told that they were at risk for cirrhosis or cancer.[135] Patients under regular review are also more likely to be interested in receiving treatment,[135] emphasizing the importance of communication and continuity of care. Several promising agents, including HCV protease and polymerase inhibitors (eg, telaprevir, boceprevir, and R7128), are in phase 2 or phase 3 trials, with a hope of availability within 2–3 years and beyond.
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Changing our Views
The impact of HCV infection on the burden of liver disease is becoming evident as individuals unknowingly infected decades ago age and develop severe sequelae of advanced liver fibrosis. Up to 1 million Americans are predicted to develop HCV-related hepatic complications during the next 2 decades.[26] Persons born between the 1940s and 1960s account for most infections, with the highest risk among those with a history of IDU or blood transfusions before 1992. Once chronic infection is established, disease progression is variable and dependent on several factors. Cirrhosis, liver failure, and HCC might occur at a faster rate and in more patients than previously believed.
The impact of HCV infection on the burden of liver disease is becoming evident as individuals unknowingly infected decades ago age and develop severe sequelae of advanced liver fibrosis. Up to 1 million Americans are predicted to develop HCV-related hepatic complications during the next 2 decades.[26] Persons born between the 1940s and 1960s account for most infections, with the highest risk among those with a history of IDU or blood transfusions before 1992. Once chronic infection is established, disease progression is variable and dependent on several factors. Cirrhosis, liver failure, and HCC might occur at a faster rate and in more patients than previously believed.
HCV infection is a health care priority. Increasing access to treatment might significantly reduce the morbidity and mortality burden of HCV infection.[136] Other measures to tackle the challenge of HCV include improving surveillance, screening and identifying patients at risk of progression, and optimizing therapy. We now need to capitalize on what we know about HCV and formulate strategies to address the anticipated surge in HCV-related morbidity and mortality. New HCV treatments are in development that might increase SVR and potentially decrease the burden of hepatic complications in populations with significant unmet need.
Hello my name is Shawn Mccreery im 39 live in Rogue Rivet Oregon, I was diagnose about 15 yrs ago with hep c 1a. I'm starting to feel pain in my liver and fatigued all the time. Im father of three my son the baby is only 5yrs old. As you can understand dying is not an option for years to come. I'm on disability since I also suffer from Sherman's. Kifosis, Wich its its deterioration of my spine, I had sleeve surgery in Mexico since my OHP insurance would not cover it here. It was a year ago and it was a success I have lost 100+pounds. For many years my doctor told me my hep had no cure and I would live 15yrs well im there and I'm scarred, is there any advice or help you could provide me? I know there is treatment for me after reading iñfo on your web, any thing will be much apreciatted. Thankyou for your time. Mccreery38@gmail.com
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