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This week someone shared a news item on HIV and smoking with us, Smoking more harmful than HIV for people taking effective treatment, US study suggests, and it got me thinking about the relationship between smoking and HCV.
According to the above article, a study this month in the Journal of Infectious Diseases (November 2016) found that “Smoking has the potential to shorten the life of a person taking HIV treatment by an average of six years, and is far more harmful to the life expectancy of people living with HIV than well-managed HIV infection itself. The study found that stopping smoking improved life expectancy, with the greatest gain in life expectancy seen when smoking was stopped by the age of 40.”
Dr Rochelle Walensky of the Massachusetts General Hospital Division of Infectious Diseases, senior author of the study, said, “It is time to recognise that smoking is now the primary killer of people with HIV who are receiving treatment.” Smoking reduces life expectancy through cardiovascular disease (stroke and heart attack), cancers and chronic obstructive pulmonary disease (emphysema).
Whew!! Okay, so where does that leave people with HIV-HCV coinfection or just with HCV who smoke, especially in terms of liver-related damage, because there have been studies which showed that smoking was directly related to liver damage and liver cancer. Those of us involved in advocacy and support all know plenty of people who smoke tobacco, and it makes me sad when I hear them coughing and knowing that many also have cirrhosis. The last thing I want to do is badger a smoker about smoking: It just doesn’t work! But on the other hand standing by watching people I know killing themselves leaves me in a moral and emotionally conflicted state.
There seems to be a general consensus that smoking has multiple effects on factors influencing hepatitis C and antiviral therapy, including lipid metabolism, fibrosis, platelet count and adherence aspects, and that smoking and HCV are independent risk factors for liver cancer (HCC).
So: I decided that it would be best to find out if smoking was really bad for people with HCV. I mean we all know that smoking isn’t any good for you, but if you have HCV will it kill you faster? And this is what I found out.
Older studies:
Several older studies found a correlation between smoking and fibrosis progression in monoinfected persons with HCV.
Smoking With Liver Disease – A No-No, from 2014, reviews a study from Hepatology which found that current and former smokers had more inflammation and scarring of their livers than did non-smokers. This finding could not be explained by other factors, such as concurrent alcohol use, that are known to aggravate the inflammation and scarring in hepatitis C. The authors concluded that patients with chronic hepatitis C should be informed that smoking cigarettes could worsen their liver disease. Dr. Marks, who reviewed the study notes, however, that “this study by itself provides limited support for an association between smoking and more severe liver damage. However, the authors cite several other studies in patients with chronic liver disease that show a similar association.”
A study from the Scandinavian Journal of Gastroenterology, Smoking and risk of liver cirrhosis: a population-based cohort study, from 2013, assessed the independent effect of smoking on alcoholic liver cirrhosis and liver cirrhosis in general. The authors concluded that smoking was associated with an increased risk of liver cirrhosis independent of alcohol intake.
An excellent article by Nicole Cutler, Smoking with Hepatitis C Raises Liver Cancer Risk, from 2009, points out that
- A French study published in the January 2003 edition of Gut found that smoking, independent of alcohol, could aggravate the histological activity of chronic Hepatitis C.
- In the June 2006 issue of Clinical Gastroenterology & Hepatology, California researchers found that smokers with chronic Hepatitis C may be more likely than non-smokers to develop liver fibrosis.
Cutler also cites a study from the International Journal of Cancer in October 15, 2008 which said this: “There appears to be a synergistic link between smoking and hepatitis C virus (HCV) infection, leading to a more than 136-fold increased risk of hepatocellular carcinoma (HCC) in men, according to a team at The University of Texas MD Anderson Cancer Center.” They also stated that “Co-infection with HCV increased risk of HCC exponentially. Cigarette Smoking, Hepatitis C Virus Synergistic in Raising Liver Cancer Risk
New Studies
All of this now brings us to data from 2 new studies on smoking and HCV. The first, Cigarette Smoking Behaviors and Beliefs in Persons Living with Hepatitis C, is from August 2016 and found that persons living with hepatitis C (PLHC) in this study population “differed from HCV- smokers in having a higher prevalence of illicit substance use, depression, and hypertension, and many harbor false beliefs about imagined benefits of smoking. They are highly motivated to quit but underutilize cessation aids. Without aggressive intervention, smoking-related morbidity will likely mute the health benefits and longevity gains associated with hepatitis C treatment.” The study does NOT talk about smoking as a cause of liver disease progression, just the effect of smoking in general and the fact that it causes morbidity in and of itself.
The last and most recent study is the most difficult to discuss. Tobacco Smoking Is Not Associated With Accelerated Liver Disease in Human Immunodeficiency Virus-Hepatitis C Coinfection: A Longitudinal Cohort Analysis, from the Canadian Co-infection Cohort study (CTN 222), concludes that, “Tobacco exposure does not appear to be associated with accelerated progression of liver disease in this prospective study of HIV-HCV coinfected individuals.” The authors did “not find evidence that tobacco smoking was associated with a faster progression to significant liver fibrosis, as measured by APRI scores, or to ESLD when comparing ever versus never smokers.” Whew!! Somebody pinch me!
Conclusion
As the authors of the Canadian Coinfection Cohort Study (a prospective and extremely well-designed study) point out, it’s not that there is no direct connection between HCV and liver disease progression, but that in many of the previous studies “that examined the cross-sectional association between tobacco smoking and accelerated liver fibrosis in HCV monoinfected patients, temporality could not be assessed and progression of liver fibrosis was not studied.”
This weakness in previous study design was also pointed out by Jay W. Marks, M.D. in the article Smoking With Liver Disease – A No-No. However, Dr. Marks concludes, that he “would feel more comfortable if there were a better-designed study to more strongly support the hypothesis that smoking cigarettes damages the liver in patients with chronic liver disease. Until such a study appears, however, I believe there is enough support to advise patients with chronic liver disease to refrain from smoking.”
Well that “better-designed study” just showed up and I have no idea what to say! CD