New Delhi: Cigarette smoking substantially reduces the lifespan of people living with Human Immunodeficiency Virus in the United States potentially even more than HIV itself, says a new study.

Massachusetts General Hospital (MGH) researcher Krishna Reddy, who led the study said, “A person with HIV who consistently takes anti-HIV medicines but smokes is much more likely to die of a smoking-related disease than of HIV. The good news is that quitting smoking can greatly increase lifespan, and it is never too late to quit.”

While only 15 percent of the general U.S. adult population smokes cigarettes, among people living with HIV the smoking rate is over 40 percent, and an additional 20 percent are former smokers. The widespread use of antiviral medications today allows people with HIV to live longer, but smokers with HIV are developing smoking-related diseases - such as lung cancer, heart disease, and chronic obstructive pulmonary disease (COPD, sometimes referred to as emphysema) - at higher rates than are HIV-uninfected individuals.

The researchers used epidemiologic data to estimate the average lifespan of people living with HIV depending on whether they were current, former or never smokers. Extending a validated simulation model of HIV developed by the team, they demonstrated that a person with HIV could lose more than 8 years of life simply because of his or her smoking habits and unrelated to HIV infection. They also found that, if one-quarter of the people receiving care for HIV in the U.S. who smoke were to quit now, more than a quarter million years of life would be saved.

The study found that for a 40-year-old person who receives care for HIV but - as is often the case in the U.S. - does not perfectly follow recommended treatment, smoking shortens his or her expected lifespan by more than 6 years, compared with a non-smoker who is similarly not perfectly adherent to antiviral treatment. For someone who adheres well to anti-HIV medicines, smoking shortens his or her expected lifespan by more than 8 years - about double the impact of HIV itself - compared with a non-smoker who perfectly adheres to treatment. For those who are smokers when they enter treatment for HIV, quitting smoking, particularly at younger ages, was shown to reverse much of the loss of life expectancy.

"Smoking cessation should be a key part of the care of people living with HIV to improve both their lifespan and their quality of life," said study co-author Travis Baggett.

Rochelle Walensky, senior author of the study, said, "It is time to recognize that smoking is now the primary killer of people with HIV who are receiving treatment."

Reddy added, "Unfortunately, smoking cessation interventions have not been widely incorporated into HIV care. Given how common smoking is among people with HIV, now is the time to change that."

The report is being published online in the Journal of Infectious Diseases.