Marie Helleberg, MD, of Copenhagen University Hospital and colleagues estimated the effect of smoking on mortality, risk of death, and life expectancy, and the number of life years lost to smoking compared to years lost to HIV among nearly 3,000 HIV-infected patients treated in Denmark from 1995 to 2010. They also compared mortality associated with smoking between HIV patients and the country's background population. Where HIV care is integrated and antiretroviral therapy is available at no cost, "more than 60 percent of deaths among HIV patients are associated with smoking," rather than HIV, Dr. Helleberg said.

Estimated life expectancy differed significantly based on smoking status. A 35-year-old HIV patient who currently smokes had a life expectancy of 62.6 years, compared to 78.4 years for a nonsmoker infected with HIV. The loss of years of life associated with smoking was twice as high as that associated with HIV among HIV-infected patients. In addition, researchers found the excess mortality of HIV-infected smokers to be three times higher than that of individuals not infected with HIV.

"Our findings emphasize the importance of counseling HIV patients on smoking cessation as smoking may impact their life expectancy considerably more than the HIV infection itself," the study authors wrote. The results also underscore the importance of prioritizing interventions for stopping smoking in HIV patient care and for the general population. Smokers who stop see their risk of cardiovascular disease drop rather quickly, but they remain at increased risk of cancer until several years after quitting.

The emphasis on well-organized HIV care is crucial, according to Dr. Helleberg and her team. Continuing to smoke -- or starting the habit -- poses extra risks for patients with HIV. Patients who receive integrated care from a variety of health care professionals, including those who can help patients address lifestyle issues, can find support for decisions to stop smoking.