People with HIV who smoke cigarettes may be at greater risk of death from smoking than from HIV/AIDS-related causes, according to a recently published study. Smoking could shorten the lifespan of an HIV-positive person by six to eight years, underlining the importance of quitting,
"It is time to recognize that smoking is now the primary killer of people with HIV who are receiving treatment," said senior study author Dr. Rochelle Walensky from Massachusetts General Hospital in Boston.
As many people with HIV live longer thanks to effective antiretroviral therapy, chronic non-AIDS-related conditions such as cardiovascular disease, cancer, and lung disease – all worsened by smoking – are a growing concern.
Studies suggest that more than 40 percent of people living with HIV in the U.S. smoke cigarettes – more than twice the rate of the population as a whole – and they are less likely to quit than HIV-negative people. This translates to 247,586 smokers receiving HIV care, according to Walensky and colleagues.
Walensky's team used a computer simulation of HIV disease progression and treatment, along with age- and sex-specific mortality data, to predict the life expectancy of HIV-positive people based on smoking status.
The study, published in the November 3 online edition of Journal of Infectious Diseases, showed that among people who maintain excellent adherence to HIV treatment, smoking reduced life expectancy by about twice as much as HIV/AIDS. Among people with lower adherence and some missed follow-up care – more typical of real-world HIV care in the U.S. – the amount of life lost to smoking was similar to that lost to HIV/AIDS.
"It is well-known that smoking is bad for health, but we demonstrate in this study just how bad it is," said study co-author Dr. Krishna Reddy, a pulmonologist at Massachusetts General Hospital. "A person with HIV who consistently takes HIV medicines but smokes is much more likely to die of a smoking-related disease than of HIV itself."
Walensky and colleagues estimated that men and women who start HIV care at age 40 with a CD4 T-cell count of 360 and maintain typical treatment adherence would lose 6.7 and 6.3 years of life, respectively, if they continued to smoke compared to those who never smoked.
However, former smokers lost only about one year of life, showing that the negative health effects of smoking can be partially reversed. Smoking cessation increased life expectancy even more than starting antiretroviral therapy earlier (with a CD4 count above 500) or improving adherence to treatment, the study found.
HIV-positive men who quit smoking when they started HIV care at age 40 could expect to regain 5.7 years of life, while women could regain 4.6 years, the researchers calculated. People who quit smoking later had smaller gains in life expectancy, but they still lived longer than those who kept smoking.
"We show that even people who have been smoking till age 60 but quit at age 60 have a substantial increase in their life expectancy," Reddy said. "So it's never too late to quit."
The study authors estimated that if 10 to 25 percent of HIV-positive smokers in the U.S. gave up smoking, they could collectively save approximately 106,000 to 265,000 years of lost life.
"This study makes clear that we must prioritize smoking cessation among adults with HIV if we want them to have an increase in the quantity (and likely quality) of life," Keri Althoff from Johns Hopkins Bloomberg School of Public Health wrote in an accompanying editorial.