Study Confirms Poorer Interferon Treatment Response in African Americans

Past research has shown that people of African descent respond less well to interferon-based antiviral therapy for chronic hepatitis C compared with Caucasians.

A recent study, reported in the August 2006 issue of Gastroenterology, confirmed that African Americans have a lower response rate, but was unable to determine the reasons for this finding.

Researchers conducted a multicenter trial that included 196 African American and 205 Caucasian patients with genotype 1 hepatitis C virus (HCV) infection. Baseline characteristics, including HCV viral load and liver disease severity, were generally similar in the two groups, but the African Americans had a higher average body weight, lower mean alanine transaminase (ALT) levels, and were more likely to have diabetes and hypertension.

Participants were treated with 180 mcg/week pegylated interferon alfa-2a (Pegasys) plus 1000-1200 mg daily ribavirin for up to 48 weeks.

Results

Racial differences in virological response to therapy were evident as early as week 4.

Sustained virological response (SVR) rates (continued undetectable HCV RNA 24 weeks after the completion of therapy) were 28% for African Americans and 52% for Caucasians (P < 0.0001).

In multiple regression analyses, Caucasians had a higher SVR rate than African Americans (relative risk 1.96; 95% CI 1.48-2.60; P < 0.0001).

Other factors independently associated with SVR included:

- female sex;

- lower baseline HCV RNA level;

- less hepatic fibrosis at baseline;

- more pegylated interferon taken.

Breakthrough viremia was more frequent among African Americans than Caucasian (13% vs. 6%, respectively; P = 0.05).

Post-treatment relapse rates were comparable in the two groups (32% in African Americans vs. 25% in Caucasians; P = 0.30).

The proportions of patients experiencing serious adverse events and rates of dose modifications or discontinuation were similar in the two groups.

Conclusion

In conclusion, the authors wrote, "African Americans with chronic hepatitis C genotype 1 have lower rates of virologic response to peginterferon and ribavirin than Caucasians. These differences are not explained by disease characteristics, baseline viral levels, or amount of medication taken."

8/25/06

Reference
H S Conjeevaram, M W Fried, L J Jeffers, and others. Peginterferon and ribavirin treatment in African American and Caucasian American patients with hepatitis C genotype 1. Gastroenterology. 131(2): 470-477. August 2006.