Smoking cigarettes substantially reduces the life expectancy of HIV-infected patients in the United States, possibly outweighing the loss from HIV infection itself, according to a study published in the Journal of Infectious Diseases.
Krishna P Reddy, from the Massachusetts General Hospital in Boston, and colleagues used a computer simulation of HIV disease and treatment to project the life expectancy of HIV-infected persons, based on their smoking status (current smoker, former smoker, or never smoker). The researchers also used age-and sex-specific data on mortality, based on smoking status. Projected survival was based on smoking status, age, and sex.
Mortality probabilities for current and former smokers were equal to those for never smokers until age 40 years. Parameters were derived from the North American AIDS Cohort Collaboration on Research and Design Data. The mean CD4 T-cell count at entry to care was 360 ± 280 cells/µL, and the median age at presentation was 43 years.
Life expectancy for men entering HIV care at age 40 years was 65.2 years, 70.9 years, and 71.9 years for current, former, and never smokers, respectively. For women, it was 68.1 years, 72.7 years, and 74.4 years, respectively. Men and women who quit smoking after entering HIV care at age 40 years gained 5.7 years and 4.6 years of life expectancy, respectively, compared with those who continued to smoke. Gains from smoking cessation decreased with age, but smokers who quit after entering care at age 60 had a gain in life expectancy of 2.5 years for men and 2.4 years for women.
Simulated 40-year-old, HIV-uninfected current smokers had a life expectancy of 72.1 years for men and 76.4 years for women, losing 10.7 years and 10.6 years of life expectancy, respectively, compared with HIV-uninfected never smokers. The researchers compared the life expectancy losses from smoking and from HIV infection in 40-year-old HIV-infected current smokers with imperfect ART adherence and retention in care. The losses associated with smoking and with HIV infection were 6.7 years and 6.9 years, respectively, for men, and 6.3 years and 8.3 years, respectively, for women. When the investigators simulated HIV-infected current smokers with perfect ART adherence and retention in care, life expectancy was 68.6 years for men and 72.1 years for women. The life expectancy losses associated with smoking and HIV infection were 8.6 years and 3.5 years, respectively, for men, and 8.2 years and 4.3 years, respectively, for women.
Keri N Althoff, from the Johns Hopkins Bloomberg School of Public Health, notes in an editorial that, “the findings presented by Reddy et al make 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. By showing that smoking cessation results in a greater gain in life expectancy than ART initiation at higher CD4+ T-cell counts or improved adherence to ART, there should be renewed urgency to implement smoking cessation programs.”
- Reddy KP, Parker RA, Losina E, et al. Impact of cigarette smoking and smoking cessation on life expectancy among people with HIV: A US-based modeling study. J Infect Dis. 3 November 2016. doi: 10.1093/infdis/jiw430
- Althoff KN. The shifting paradigm of care for adults living with HIV: Smoking cessation for longer life. J Infect Dis. 3 November 2016. doi: 10.1093/infdis/jiw434