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Background:   Although the majority of those chronically infected with hepatitis C virus (HCV) are injection drug users (IDU), data on liver fibrosis progression (FP) by paired biopsies in this population are sparse.  Rates of FP and predictors of FP were assessed among a community-based cohort of HIV⁺ and HIV^- IDU.

Methods:  Between 1996 and 1998, baseline liver biopsies were obtained on a random sample of 1667 HCV-infected IDU participating in a community-based natural history study. Subjects were followed every 6 months with liver enzyme testing and questionnaires. A second biopsy was offered to subjects with no contraindication. Paired biopsies were scored from 0 to 6 according to the modified histologic activity index (MHAI).  FP was defined as an increase in fibrosis score of = 2 units. Factors associated with FP were evaluated by Chi-square testing and Mantel Haenszel for categorical data. Wilcoxon rank sum compared continuous data non-parametrically.

Results:   Of 116 IDU with paired liver biopsies (median: 4 years apart), the sample was 28% HIV⁺, 95% African American, 82% male and median age was 42 years.  51% were current IDU, 60% used alcohol. Median estimated duration of HCV infection was 21 years.  Ishak-modified fibrosis scores at follow-up liver biopsy were:  52% <2, 42% between 2 and 4, and 6% between 5 and 6.  Compared with the initial biopsy, the median progression rate (fibrosis units/year) was 0.11 (range -0.68 to 1.42), and did not significantly differ by HIV status.  FP occurred in 21%.  Those with FP had higher baseline HCV RNA levels (median 7.15 vs 6.63 log₁₀ units, p = 0.03).  Risk of FP was higher with elevated liver transaminases at serial study visits (e.g., ALT: trend for always normal, >50% normal and the rest, p = 0.03).  A trend was seen with greater FP with increased alcohol use and with increased IDU at study visits. Age, gender, race, duration of HCV infection, interferon therapy, HIV status, CD4 count, MHAI inflammatory score or fatty liver change were not associated with FP.  A trend was seen for an increased risk of FP with HAART use reported at >50% of study visits (23.1% vs 10.5%). 

Conclusions: In this setting, overall FP rates were relatively low, even among those HIV infected, and especially among those with low serum liver enzyme levels. Nonetheless, further research is needed to understand the basis for the marked person-to-person differences in the risk of FP that cannot be explained by liver enzymes or HIV status.

Keywords: Hepatitis C; Co-Infection; Fibrosis