Frequent Cannabis Use is Associated with Worse Liver Fibrosis Progression in Hepatitis C Patients

Daily marijuana use may contribute to the progression of liver fibrosis in people with chronic hepatitis C, according to a report published in the January 2008 issue of Clinical Gastroenterology & Hepatology; the study was previously presented at the 57^th meeting of the American Association for the Study of Liver Disease (AASLD) in October 2006.

Researchers from the University of California at San Francisco interviewed 204 patients with chronic hepatitis C between 2001 and 2004, assessing demographic characteristics, HCV risk factors, and use of cannabis and alcohol. Participants underwent virological testing and liver biopsies, which were scored according to the Ishak system (stages F0 to F6).

The median age of the study participants was 47 years, 69% were men, 49% were white, 21% were coinfected with HIV, most were low income, and for 70% the presumed route of HCV infection was injection drug use. The median lifetime duration of alcohol use was 29 years, with a median of about 2 drinks per day.

Results

• 13.7% of the participants reported daily cannabis use within the past 12 months, 45.1% reported occasional use, and 41.2% said they never used marijuana.

• Fibrosis stage distribution was as follows:

o        F0 (absent): 27.5%;

o        F1-F2 (minimal to mild): 55.4%;

o        F3-F6 (moderate to severe): 17.2%.

• Daily cannabis use (compared with occasional or no use) was strongly associated with moderate to severe (F3-F6) fibrosis (univariate analysis OR 3.21, P = 0.020; multivariate analysis OR 6.78, P = 0.003).

• Other independent predictors of moderate to severe fibrosis were:

o        Greater lifetime duration of moderate to heavy alcohol use (1.72 per 10 years; P = 0.044)

o        > 11 portal tracts (compared to < 5; OR 6.92; P = 0.021).

o        Age was of borderline significance (OR 2.19 per 10 years; P = 0.064).

• Daily cannabis use was not strongly associated with mild (F1-F2) fibrosis compared with absent (F0) fibrosis in univariate or multivariate analyses.

• Independent predictors of mild fibrosis were:

o        Higher HCV viral load (OR 1.86 per log increase; P = 0.009);

o        5-11 or > 11 portal tracts (compared to < 5) (OR 3.43, P = 0.002 and OR 10.4, P < 0.001, respectively);

• Age, sex, race, duration of HCV infection, HCV genotype, HIV status, body weight, tobacco use, and lifetime alcohol use were not significantly associated with mild fibrosis.

Conclusion

In conclusion, the researchers wrote, “Daily cannabis use is strongly associated with moderate to severe fibrosis.”

They recommended that, “HCV-infected individuals should be counseled to reduce or abstain from cannabis use.”

This data supports previous studies showing that frequent cannabis use is associated with more severe fibrosis, faster fibrosis progression, and advanced liver steatosis (fat accumulation).

While long-term frequent cannabis use may be detrimental to people with chronic hepatitis C, other research has shown that medicinal use of cannabis during interferon-based therapy can relieve side effects and help patients stay on treatment, thereby improving their chances of sustained response.