Cohort study of electronic cigarette use: effectiveness and safety at 24 months

• Published in: Tobacco control 2017-05, Vol.26 (3), p.284-292
• Main Authors: Manzoli, Lamberto, Flacco, Maria Elena, Ferrante, Margherita, La Vecchia, Carlo, Siliquini, Roberta, Ricciardi, Walter, Marzuillo, Carolina, Villari, Paolo, Fiore, Maria
• Format: Article
• Language: English
• Subjects: Abstinence; Adult; Aged; Carbon monoxide; Cigarettes; Cohort analysis; Cohort Studies; Electronic cigarettes; Electronic Nicotine Delivery Systems - adverse effects; Female; Follow-Up Studies; Health care; Humans; Male; Middle Aged; Missing data; Prospective Studies; Regression analysis; Research Paper; Self report; Smoking; Smoking - adverse effects; Smoking - epidemiology; Smoking Cessation - methods; Surveys and Questionnaires; Tobacco; Tobacco Products - adverse effects; Variables
• ISSN: 0964-4563; 1468-3318
• DOI: 10.1136/tobaccocontrol-2015-052822

ObjectiveTo evaluate the safety and effectiveness of e-cigarettes, by comparing users of only e-cigarettes, smokers of only tobacco cigarettes and dual users.DesignProspective cohort study. We update previous 12-month findings and report the results of the 24-month follow-up.Data sourcesDirect contact and questionnaires by phone or via internet.MethodsAdults (30–75 years) were classified as: (1) tobacco smokers, if they smoked ≥1 tobacco cigarette/day, (2) e-cigarette users, if they inhaled ≥50 puffs/week of any type of e-cigarette and (3) dual users, if they smoked tobacco cigarettes and also used e-cigarettes. Carbon monoxide levels were tested in 50% of those declaring tobacco smoking abstinence. Hospital discharge data were used to validate possibly related serious adverse events in 46.0% of the sample.Main outcome measuresSustained abstinence from tobacco cigarettes and/or e-cigarettes after 24 months, the difference in the number of tobacco cigarettes smoked daily between baseline and 24 months, possibly related serious adverse events.ResultsData at 24 months were available for 229 e-cigarette users, 480 tobacco smokers and 223 dual users (overall response rate 68.8%). Of the e-cigarette users, 61.1% remained abstinent from tobacco (while 23.1% and 26.0% of tobacco-only smokers and dual users achieved tobacco abstinence). The rate (18.8%) of stopping use of either product (tobacco and/or e-cigarettes) was not higher for e-cigarette users compared with tobacco smokers or dual users. Self-rated health and adverse events were similar between all groups. Among those continuing to smoke, there were no differences in the proportion of participants reducing tobacco cigarette consumption by 50% or more, the average daily number of cigarettes and the average self-rated health by baseline group. Most dual users at baseline abandoned e-cigarettes and continued to smoke tobacco. Those who continued dual using or converted from tobacco smoking to dual use during follow-up experienced significant improvements in the 3 outcomes compared with those who continued or switched to only smoking tobacco (p