Among people with hepatitis C virus (HCV), unhealthy behaviors such as smoking contribute as much to their higher risk of death as the virus itself.

Analyzing data from the 1999 to 2010 National Health and Nutrition Examination Surveys, researchers found that compared with HCV-negative participants, HCV-positive individuals were 2.3 times more likely to report current excessive alcohol use (18.7 percent of those with hep C versus 8.3 percent of those without hep C), 2.3 times more likely to report currently smoking cigarettes (63.8 percent versus 28.2 percent), 93 times more likely to report current injection drug use (9.3 percent versus 0.1 percent) and 3.4 times more likely to report current non-injection-drug use (16.2 percent versus 4.7 percent).

After adjusting the data to account for differences in sociodemographic factors, the researchers found that those with hep C had a 2.36-fold higher risk of death, or mortality risk ratio (MRR), than those without the virus. Adjusting for sociodemographic factors and current unhealthy behaviors reduced the MRR by 51.5 percent. This means that current unhealthy behaviors were apparently responsible for half of the excess death risk among the hep C population.

Current cigarette smoking affected the death risk the most. After the data were adjusted for such individual behavioral factors, smoking was responsible for 30 percent of the reduction in the MRR, suggesting that quitting smoking likely provides a very significant reduction in the risk of death among people with hep C.