Individuals with hepatitis C infection who use cannabis were also found to have lower total healthcare costs than non-users.
In an observation of a large pool of patients with hepatitis C virus (HCV), cannabis users had a lower prevalence of liver cirrhosis, more favorable health status at hospital discharge, and lower total health care costs than non-users.
Adeyinka Adejumo, lead author of the study and graduate student at the University of Massachusetts Intercampus Program in Biomedical Engineering and Biotechnology, and colleagues indicated the findings add to a relationship between cannabis use and HCV that have been “controversial, and remains unclear."
Although there have been reports of detrimental effects of cannabis in HCV infected individuals, Adejumo and colleagues note more recent preclinical and population evidence of cannabis modulating inflammatory and fibrotic processes in the liver, plus a lone report of reduced steatosis.
To further assess the interaction of cannabis with HCV infection outcomes, Adejumo and colleagues examined the medical records of over 900,000 subjects with chronic HCV infection, drawing on data from patients hospitalized between 2007-2014 in the Healthcare Cost and Utilization Project Nationwide Inpatient Sample, the largest inpatient database in the US.
Cannabis users were identified from ICD-9-CM codes related to use of Indian hemp, marijuana and other varieties of cannabinoid-containing products. Demographic data included age, gender, race, health insurance, and income. A range of comorbidities were determined, including peripheral vascular disease, chronic heart failure and hypertension.
The investigators matched demographics and comorbidities to compare outcomes in 4728 cannabis users and 4728 non-users. In addition to determining the prevalence of liver cirrhosis and liver carcinoma, they considered such hospitalization outcomes as mortality, discharge disposition, cost and length of stay.
"Our novel study, to the best of our knowledge, represents the largest population-based study to assess the effect of cannabis use on chronic liver disease associated with HCV infection," investigators noted.
After propensity matching cohorts, the investigators found cannabis users had lower frequencies for liver cirrhosis and related complications, fewer unfavorable conditions at hospital discharge, and lower total health care costs. There was no difference between the groups on the incidence of liver carcinoma, in-hospital mortality, or length of stay.
In post hoc analysis stratifying cannabis users into dependent and non-dependent groups, the decrease in prevalence of liver cirrhosis from non-users was 15% and 48% among non-dependent and dependent users, respectively. Between user groups, the dependent users had a 38% lower prevalence than non-dependent users.
The investigators credit their use of propensity matching for demonstrating the favorable outcomes with cannabis that had not been revealed in older studies which included many confounding factors. They speculated that beneficial effects of cannabis may be related to a variety of factors, from exerting direct toxicity on profibrotic hepatic stellate cells to reducing nausea to better enable patients to adhere to their antiviral medication regimen.
"The potential roles played by cannabis on liver disease progression in HCV positive patients will require additional complementary evaluation by way of prospective studies," investigators noted.
The study, "Reduced Incidence and Better Liver Disease Outcomes among Chronic HCV Infected Patients Who Consume Cannabis," was published online in the Canadian Journal of Gastroenterology and Hepatology.