March 1, 2010
The risk of cardiac events drops sharply when HIV-positive smokers quit, mirroring what is seen in people not infected with the virus, according to preliminary data presented at the recent 17th Conference on Retroviruses and Opportunistic Infections.
The finding comes from the Data Collection on Adverse Events of Anti-HIV Drugs (DAD) study, which was designed to investigate cardiovascular risks associated with various HIV treatments. Kathy Petoumenos, PhD, of the University of New South Wales, and colleagues assessed risk of myocardial infarction; coronary heart disease, including MI; cardiovascular disease (CVD), including CHD and stroke; and all-cause mortality. The international cohort of 27,000 participants included 8,920 who had never smoked and served as a control.
Compared to the control group, previous smokers had a 73 percent increase in MI risk, a 60 percent increase in CHD risk and a 38 percent increase in CVD. Current smokers had a 3.4-fold elevated risk for MI, 2.5-fold for CHD, and 2.2-fold for CVD, respectively, compared to the control group. Current but not previous smokers had an increased risk for all-cause mortality.
According to the team, the key finding was that quitting smoking during the study reduced the risk of an adverse cardiac outcome. For MI, smoking cessation for less than a year still was associated with a 3.73-fold elevated risk, but this dropped to 2.07-fold after three years. For CHD, elevated risk fell from 2.93-fold to 1.83-fold. For CVD, elevated risk fell from 2.32-fold to 1.49-fold -- the latter not being significantly different from that seen among never-smokers. However, quitting smoking had no significant effect on all-cause mortality, said Petoumenos.
A lack of data on smoking start and stop dates and the number of pack-years smoked limits the study's findings, Petoumenos said. Due to the nature of the study, she added, it is not possible to make inferences about cause and effect.
Even so, "These are the data you can use to persuade a patient to stop smoking," said Andrew Carr, MD, a member of the conference program committee and a staffer at St. Vincent's Hospital, Sydney.