Cigarette and e-cigarette dual use and risk of cardiopulmonary symptoms in the Health eHeart Study

There were no significant differences in e-cigarette dose measures (i.e. days of use in the past month, cartridges/refills per day, puffs per day) between dual users and exclusive e-cigarette users. Compared to cigarette only smokers, dual users had significantly worse general health scores (p=0.002). After adjusting for covariates, the only cardiovascular condition significantly different between dual users and cigarette smokers was history of arrhythmia (17.8% v. 14.2%, p=0.02). In comparisons of all four groups, exclusive e-cigarette users had worse health scores (n=588, score: 3.5) compared to those who reported no product use (n=36506, score: 3.8) but better scores than cigarette-only users (n=1626, score: 3.4) and dual users (n=480, score: 3.3), p<0.0001. For respiratory effects, e-cigarette only users reported more breathing difficulty (typical) than no product users (n=483, score: 2.3; n=31924, score: 1.8) but lower difficulty than cigarette only users (n=1274, score: 2.5) and dual users (n=365, score: 2.5), p<0.0001. This association was also reflected in past-month breathing difficulty (p<0.0001). Further, dual users had the highest rate of asthma (n=69, 17.9%), followed by e-cigarette users (n=81, 16.5%), then cigarette smokers (n=195, 14.7%) and non-users (n=3356, 10.3%), p=0.003. Regarding cardiovascular outcomes, e-cigarette users reported more chest pain (n=232, 47.3%) than non-users (n=10730, 32.9%) but less than cigarette users (n=685, 52.0%) and dual users (n=197, 51.7%), p<0.0001. E-cigarette users also reported more palpitations than non-users (n=266, 55.3% vs. n=14477, 44.5%) but similar to cigarette users (n=721, 54.8%) and dual users (n=211, 55.5%), p=0.002. Fewer e-cigarette users reported high blood pressure (n=167, 34.0%) than all other groups, non-users (n=11931, 36.5%), cigarette smokers (n=507, 38.2%), and dual users (n=157, 40.9%), p=0.02. E-cigarette users reported slightly more coronary artery disease than non-users (n=54, 10.9% vs. n=3248, 9.9%), but less than cigarette smokers (n=174, 13.0%) and dual users (n=54, 14.0%), p<0.0001. The highest reported cases of arrhythmia were observed in dual users (n=66, 17.8%), followed by e-cigarette users (n=74, 15.1%), then cigarette smokers (n=183, 14.2%) and non-users (n=4444, 13.8%), p=0.001. COPD was reportedly lowest among non-product users (n=1209, 3.7%), followed by e-cigarette users (n=33, 6.7%), then cigarette users (n=146, 11.0%) and dual users (n=47, 12.2%), p=0.001. Following adjustment, comparisons for high cholesterol, heart attack, blocked arteries in legs, blood clots, congestive heart failure, stroke, enlarged heart, atrial fibrillation, and cardiac arrest were not significant different between the four groups.
Results of comparisons for adverse events showed that fewer e-cigarette users reported cases of diabetes (n=33, 6.7%) than non-users (n=2578, 7.9%), cigarette smokers (n=129, 9.7%), and dual users (n=47, 12.2%), p=0.02. Tests for lost consciousness and sleep apnea were not significant following adjustment. Authors concluded that "[t]hese study findings provide early epidemiologic evidence to suggest that dual users are at higher risk of breathing difficulty and arrhythmias, and that this increased risk is likely attributable to e-cigarette use or the potential combined effect of cigarette and e-cigarette use" (p. 10).

Wang, J. B., Olgin, J. E., Nah, G., Vittinghoff, E., Cataldo, J. K., Pletcher, M. J., & Marcus, G. M. (2018). Cigarette and e-cigarette dual use and risk of cardiopulmonary symptoms in the Health eHeart Study. PloS One, 13(7), e0198681.