A new study has found that daily use of marijuana increases the severity of the disease in patients with chronic hepatitis C (HCV).
The researchers also found that patients with moderate to heavy alcohol use combined with regular cannabis use had even greater risk of liver fibrosis.
Hepatitis is an inflammation of the liver. Hepatitis C is the most common form of hepatitis and infects nearly 4 million people in the U.S., with an estimated 150,000 new cases diagnosed each year.
According to Dr Norah Terrault, lead researcher and MPH, from the University of California, San Francisco, it is important to identify risk factors to prevent or lessen the progression of the disease.
"Hepatitis C is a major public health concern and the number of patients developing complications of chronic disease is on the rise," said Terrault.
"It is essential that we identify risk factors that can be modified to prevent and/or lessen the progression of HCV to fibrosis, cirrhosis and even liver cancer. These complications of chronic HCV infection will significantly contribute to the overall burden of liver disease in the U.S. and will continue to increase in the next decade," she added.
The study was conducted over 204 patients where baseline characteristics of those included in the study were similar to those excluded with the exception of daily cannabis use.
The findings revealed that patients who used cannabis daily had a significantly lower body mass index than non-daily users (25.2 versus 26.4) and were more likely to be using medically prescribed cannabis (57.1 percent versus 8.79 percent), and more likely to have HIV coinfection (39.3 percent versus 18.2 percent).
The team also examined other factors contributing to increased fibrosis including age at enrolment, lifetime duration of alcohol use, lifetime duration of moderate to heavy alcohol use and necroinflammatory score (stage of fibrosis).
The analysis of the combined factors revealed that there was a strong (nearly 7-fold higher risk) and independent relationship between daily cannabis use and moderate to severe fibrosis.
The study appears in Clinical Gastroenterology and Hepatology, the official journal of the American Gastroenterological Association (AGA) Institute.