If You Smoke, Adding in E-Cigs Likely Won’t Cut CV Risks

People who use both combustible-tobacco cigarettes and e-cigarettes have the same risk of cardiovascular disease as those who smoke exclusively, according to a longitudinal analysis of US-based data from the Population Assessment of Tobacco and Health (PATH) study.

Results from the observational study also hinted at lower risk for people who only use e-cigarettes, but these constituted a minority of study participants, researchers caution, and the number of events in this group was small. Their findings, published recently in Circulation, follow a prior analysis of PATH showing dual use doesn’t appear to be a safer option compared with only smoking tobacco when it comes to markers of subclinical atherosclerosis.

Jonathan B. Berlowitz, BA (Boston University School of Public Health, MA), lead author of the new report, said they hadn’t known what to expect when looking at clinical outcomes.

“On one hand, some people use e-cigarettes to reduce their total cigarette consumption, suggesting a possible mechanism where dual use could’ve been associated with decreased cardiovascular risk,” he said. “However, other people supplement their cigarette smoking with additional e-cigarette use without cutting down,” he added.

The lack of difference between the tobacco-only and dual-use groups highlights the “importance of complete cigarette cessation for reducing cardiovascular risk,” Berlowitz told TCTMD. Cardiologists should continue to emphasize this message, he advised.

Getting combustible tobacco out of your life is the best thing that you can do, certainly for cardiovascular risk factors but actually for a whole bunch of different negative outcomes. Douglas Jorenby

Douglas Jorenby, PhD (University of Wisconsin Center for Tobacco Research and Intervention, Madison), commenting on the PATH analysis for TCTMD, said that it’s useful, but comes with caveats. The main one, he said, is that the cohort was skewed to a younger sample, whereas CVD events tend to cluster later in life.

Still, “it syncs up very nicely with what we’ve seen both in terms of focused laboratory studies . . . looking very carefully in real time at carcinogens and other risk factors,” he said, as well as what Jorenby’s seen in his own research on dual users. “It seems like if people are using combustible tobacco to any extent they’re putting themselves at risk.”

Although he’s open to the “harm reduction” concept, said Jorenby, when it comes to things like CVD and cancer risk, “it really does seem like it just sorts out into two groups: the people who are not using combustible tobacco at all and the people who are using it to any degree. . . . . Getting combustible tobacco out of your life is the best thing that you can do, certainly for cardiovascular risk factors but actually for a whole bunch of different negative outcomes.”

Dual Use Not Harm Free

Berlowitz and colleagues analyzed information on smoking habits for 24,027 people who took part in PATH, a nationally representative cohort study that collected five annual waves of self-reported data. Half were younger than 35, and 51% were women. Each participant contributed no more than 4 years of follow-up from baseline until a CVD diagnosis, loss to follow-up, or the end of the study (whichever came first).

Just 3.4% of participants said they exclusively used e-cigarettes, while 27.1% reported smoking only tobacco and 7.7% used both products. Fully 61.7% said they did not use either.

Exclusive e-cigarette users and dual users tended to be younger than nonusers (with 62% and 54%, respectively, vs 51% younger than 35 years), but they had a higher number of pack-years (mean 11.0 and 15.7 vs 4.2).

There were 1,487 cases of “any CVD,” defined as self-reported diagnosis of MI, bypass surgery, heart failure (HF), other heart condition, or stroke within the past year. For the composite endpoint of MI, HF, or stroke, there were 519 events.

Compared with nonusers, individuals were at higher risk of both any CVD and the composite of MI, HF, or stroke if they exclusively smoked tobacco or were dual users. Those who used only e-cigarettes were not at higher risk.

Risk Compared With Nonuse: Mutivariable-Adjusted HR (95% CI)

Compared with smoking only tobacco, dual use carried similar risks of both endpoints. However, e-cigarette users were at lower risk of any CVD (multivariable-adjusted HR 0.66; 95% CI 0.46-0.94). The difference between e-cigarettes and tobacco did not reach significance for the endpoint of MI, HF, or stroke.

Berlowitz said it’s hard to read much into the apparently lower risk for people just using e-cigarettes, given that events were self-reported and the link was only significant for the broadest definition of CVD they analyzed. A growing body of literature suggests, however, that while e-cigarettes aren’t harmless, they do carry less potential for harm than tobacco, he noted. “We’ll see. As more research comes out on this topic, I think we’ll gain further insights on that.”

Larger studies with longer follow-up are needed, he said. Being able to separate out a cohort of people who have only used e-cigarettes and never used tobacco would be useful. “We also hope to see research on factors that could modify the association between e-cigarettes and cardiovascular disease, such as e-cigarette device type and flavors,” Berlowitz said, “because those can deliver different levels of toxins to users.”

What will be interesting, Jorenby noted, is to see how the changing array of products—both combustible tobacco and e-cigarettes—will affect behavior and impact risk. “Part of the appeal of vaping for a lot of people is that there are taste options,” like fruit and candy-like flavors, which are now mostly banned by the US Food and Drug Administration. If the agency is successful in its effort to get rid of menthol cigarettes and flavored cigars, consumers could soon be left with only tobacco-flavored products, somewhat leveling the playing field.