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Dual use of traditional cigarettes, e-cigarettes may not reduce heart disease risk

Reuters Health - 04/01/2021 - Smokers who replace some of their traditional cigarettes with e-cigarettes do not reduce their levels of biomarkers associated with heart disease risk, a new study suggests.

In an analysis of data from more than 7,000 adults, researchers found participants who exclusively vaped had the same levels of inflammatory and oxidative stress biomarkers as non-smokers, but smokers with mixed use had similar levels to those who used traditional cigarettes only, according to the report published in Circulation.

Because e-cigarettes are so new, it's not possible to evaluate long-term outcomes, said the study's lead author, Andrew Stokes, an assistant professor in the department of global health at the Boston University School of Public Health.

"But we can look for evidence of subclinical cardiovascular harm through biomarkers," Stokes said. "And we find that there is no evidence that using both e-cigarettes and traditional cigarettes, one of the most common types of smoker, leads to any risk reduction relative to smoking traditional cigarettes only."

In most cases, people using both e-cigarettes and traditional cigarettes are looking for harm reduction, Stokes said.

"There is a perception that by substituting e-cigarettes for traditional cigarettes, people will partially reduce the harms of smoking," he added. "To get any harm reduction from e-cigarette use, you need to fully substitute them for traditional cigarettes. A little combustible cigarette use increases the risk of cardiovascular disease substantially. Even if you reduce from two packs per day to one pack per day, that may not be enough for a person to see any reduction in cardiovascular harm."

To explore the possibility that replacing some traditional cigarettes with e-cigarettes might reduce the smoking-related risk of heart disease, Stokes and his colleagues turned to the Population Assessment of Tobacco and Health (PATH) Study, a nationally-representative, longitudinal cohort in the U.S. The current analysis focused on participants in the Wave 1 survey administered from 2013 to 2014, which included the collection of blood and urine samples.

Stokes and his colleagues included adults aged 18 and older with data on biomarkers and smoking habits. The 7,130 participants were grouped into four categories based on cigarette/e-cigarette use behavior in the past 30 days: non-use, exclusive e-cigarette use, exclusive combustible cigarette use, and dual use.

The researchers examined biomarkers of inflammation (high sensitivity C-reactive protein, interleukin-6, fibrinogen, soluble intercellular adhesion molecule) and oxidative stress (urinary 8-isoprostatane). In their multivariate analysis, they accounted for factors that might impact cardiovascular risk assessment, including race/ethnicity, gender, age, education, socioeconomic status, BMI, diabetes status, and heart disease.

Of the 7,130 participants, 58.6% did not use either type of cigarette, 1.9% exclusively vaped, 29.5% exclusively smoked and 9.9% used both types of cigarette. Exclusive use of traditional cigarettes and dual use were associated with higher levels of all biomarkers as compared to non-use. Compared to smoking traditional cigarettes, exclusive vaping had significantly lower levels of almost all inflammatory and oxidative stress biomarkers, with the only exception being high sensitivity C-reactive protein. The levels for exclusive vaping were comparable to those for non-use.

Dual use had comparable levels of all five inflammatory and oxidative stress biomarkers to exclusive use of combustible cigarettes.

Dr. Matthew Steinhauser was not surprised by the new findings.

Even those who don't smoke traditional cigarettes much see an increase in heart disease risk, Dr. Steinhauser said.

"What I tell my patients is, I would rather have you smoke fewer than more cigarettes," he said. "There is a dose response for a lot of health endpoints, whether it's heart disease or cancer. So, I try to get them to cut back before they quit entirely. That said, even one a day has impacts on inflammation and blood vessel biology that are important and harmful."

While there's a growing body of evidence suggesting that e-cigarettes are less dangerous than combustible cigarettes, "I don't think we can say they are totally safe. One can view them as the lesser of two evils," he added.

"They are different from nicotine replacement in the form of gum or a patch," Dr. Steinhauser said. "They are ignited and that can change the chemistry of what's in them. Also, there are fillers that vary from company to company and we don't have a great understanding of how fillers may be toxic or may not be toxic."

SOURCE: https://bit.ly/3nlMtlf Circulation, online January 4, 2021.

By Linda Carrol

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