What Factors Influence Adherence to Treatment for Hepatitis C?

Efficacy, or likelihood of achieving sustained virological response, was the most important factor influencing adherence among people considering treatment for chronic hepatitis C, according to a recent survey. Other factors affecting adherence included depression, flu-like symptoms days, lost work days, hair loss, and type of interferon injection equipment.

Epidemiology and Management of HCV Genotype 6

Prevalence of hepatitis C virus (HCV) genotype 6 may be as high as 50% in parts of Southeast Asia, according to a systematic review published in the August 2011 issue of Alimentary Pharmacology and Therapeutics. Compared with genotypes 1 and 4, genotype 6 responds better to interferon-based therapy.

HCV genotypes 1, 2, and 3 are most common in the U.S. and Western Europe and have been more extensively studied than the other major genotypes -- 4, 5, and 6.

D.T. Chao from Michigan State University and colleagues performed a comprehensive review of the medical literature on HCV genotype 6.

HCV genotype 6 is most often seen in Southeast Asia and the surrounding areas including China, which have a high overall prevalence of hepatitis C (up to 6%-7%, as compared with about 2% in the U.S.) as well as hepatitis B. Nearly one-third of immigrants from Southeast Asia, China, and Hong Kong to the U.S. who test positive for chronic hepatitis C have HCV genotype 6, the study authors noted as background.

Older tests may have misclassified HCV genotype 6 as genotype 1, but newer line probe assays can more accurately and reliably determine genotype, they noted.

The researchers searched the PubMed database for "hepatitis C AND genotype 6." Their search returned a total of 47 articles, of which 33 were determined to be relevant to the review. Additional articles were identified using the reference lists from these 33 articles.

Results

• The prevalence of HCV genotype 6 was estimated to be as high as 50% in some regions of Southeast Asia.
• Risk factors for HCV genotype 6 among Asian patients are similar to those for other HCV genotypes, with a majority of people not recalling specific exposure risks.
• Asian patients tend to have different risk factors for HCV acquisition than Caucasians, often being exposed through unsanitary medical procedures.
• Genotype 6 infection rates are high among injection drug users (IDUs) and people with thalassemia major (an inherited form of anemia), who often require blood transfusions; studies have shown that genotype 6 is the most common type among IDUs in Southeast Asia.
• Only 1 published study addressed clinical characteristics of HCV genotype 6, finding that people with HCV genotype 1 and 6 had somewhat higher baseline viral load than those with genotypes 2 and 3.
• Genotype 6 patients "did not otherwise demonstrate any significant differences" with regard to host factors (e.g. age, family history of chronic hepatitis C, hepatitis B, or hepatocellular carcinoma), baseline laboratory values (e.g. ALT, bilirubin, white blood cell count, platelet count), or liver histology compared with other HCV genotypes.
• Overall, studies found that patients with HCV genotype 6 responded better to interferon-based therapy than those with genotype 1.
• 7 retrospective analyses found sustained virological response (SVR) rates to pegylated or conventional interferon plus ribavirin ranging from 62% to 92% for genotype 6, compared with 29% to 62% for genotype 1.
• 1 study found that sustained response rates were similar for genotype 6 patients treated for 24 weeks (the standard duration for genotypes 2 and 3) or 48 weeks (the standard duration for genotype 1).
• As is the case with other genotypes, predictors of poor response among patients with genotype 6 included suboptimal treatment adherence, high body mass index, and older age.
• Rapid virological response (undetectable HCV RNA at week 4 of treatment) was found to be a significant predictor of SVR for genotype 6 patients, but the predictive value of early virological response at week 12 is unclear.
• The effect of race/ethnicity on genotype 6 treatment response is "not clearly defined"; however, prior reports of better response among Asians vs Caucasians with genotype 1 may be due to the fact that some Asians with easier-to-treat genotype 6 were misclassified as having genotype 1.
• Frequency and types of side effects of interferon-based therapy were similar for people with genotype 6 and other HCV genotypes.

Based on these findings, the study authors summarized, "HCV genotype 6 patients do not demonstrate any significantly different clinical characteristics compared with patients infected with HCV of other genotypes."

"Patients infected with HCV genotype 6 can expect higher SVR compared with patients with HCV genotype 1 and their SVR to [pegylated interferon] and [ribavirin] is probably similar to that of patients with HCV genotypes 2 and 3," they continued. "SVR rates also appear to be similar in patients with HCV genotype 6 who receive 24 weeks of [pegylated interferon] and [ribavirin] and those who receive 48 weeks of therapy, though additional studies are needed to recommend 24 weeks as the optimal treatment duration for these patients."

In conclusion, the authors recommended, "Future studies should seek to clarify issues regarding early predictors for treatment response in patients with HCV genotype 6, and the impact of ethnic and genotypic factors to treatment response in HCV genotype 6 patients."

Investigator affiliations: College of Human Medicine, Michigan State University, East Lansing, MI; Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan; Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, CA.

8/23/11

Reference

T Chao, K Abe, and MH Nguyen.   Systematic review: epidemiology of hepatitis C genotype 6 and its management. Alimentary Pharmacology and Therapeutics  34(3): 286-296 (free full text). August 2011.
 

FDA Approves Pegasys plus Ribavirin for Children with Chronic Hepatitis C

The U.S. Food and Drug Administration (FDA) has approved pegyalted interferon alfa-2a (brand name Pegasys) plus ribavirin (brand name Copegus) for previously untreated children and adolescents age 5-17 with chronic hepatitis C virus (HCV) infection.

Telaprevir (Incivek) Approved in Canada

The hepatitis C virus (HCV) protease inhibitor telaprevir (brand name Incivek) -- one of the first 2 direct-acting antiviral drugs for genotype 1 chronic hepatitis C -- was approved in Canada this week. Telaprevir and another HCV protease inhibitor, boceprevir (Victrelis), were approved by the U.S. Food and Drug Administration (FDA) this past May.

HCV Polymerase Inhibitor PSI-938 Gets Fast Track Status

The U.S. Food and Drug Administration (FDA) last week granted a "fast track" designation for PSI-938, an investigational nucleotide analog hepatitis C virus (HCV) polymerase inhibitor being developed by Pharmasset.

TAG Offers New Guide to Clinical Trials for People with Hepatitis C

The Treatment Action Group (TAG) has produced a new booklet for people considering taking part in clinical trials for new therapies for hepatitis C.

Insulin Resistance Affects Sustained Response to Hepatitis C Treatment

Greater insulin resistance was association with poorer response to pegylated interferon plus ribavirin regardless of hepatitis C virus (HCV) genotype, according to a meta-analysis described in the August 2011 issue of Alimentary Pharmacology and Therapeutics.

FDA Updates Dosing of Pegasys plus Ribavirin for Hepatitis C Patients with Kidney Impairment

On August 9, 2011, the U.S. Food and Drug Administration (FDA) approved changes to the product label information for pegylated interferon alfa-2a (Pegasys) plus the Copegus brand of ribavirin, reflecting new dose recommendations for people with impaired kidney function.