More information about text formats
NOT PEER REVIEWED
We would like to thank Mr. Wang for his feedback on our paper, Indicators of dependence and efforts to quit vaping and smoking among youth in Canada, England and the USA.
With regards to the ‘discrepancies’ in vaping and smoking prevalence between those reported in Table 1 and an earlier publication , we have previously published these same estimates , along with a description of the survey weighting procedures—which were modified since the first estimates were published (as outlined in a published erratum to the cited publication ). Briefly, since 2019, we have been able to incorporate the smoking trends from national ‘gold standard’ surveys in Canada and the US into the post-stratification sampling weights. A full description is provided in the study’s Technical Report , which is publicly available (see http://davidhammond.ca/projects/e-cigarettes/itc-youth-tobacco-ecig/).
Mr. Wang has also noted a change in the threshold used for a measure of frequent vaping/smoking: ≥20 days in past 30 days rather than ≥15 days, as previously reported . We have adopted the convention of reporting using ≥20 days in past 30 days to align with the threshold commonly used by the US Centers for Disease Control for reporting data from the National Youth Tobacco Survey (NYTS), as well as the Population Assessment of Tobacco and Health (PATH) Study and the Mo...
Mr. Wang has also noted a change in the threshold used for a measure of frequent vaping/smoking: ≥20 days in past 30 days rather than ≥15 days, as previously reported . We have adopted the convention of reporting using ≥20 days in past 30 days to align with the threshold commonly used by the US Centers for Disease Control for reporting data from the National Youth Tobacco Survey (NYTS), as well as the Population Assessment of Tobacco and Health (PATH) Study and the Monitoring the Future (MTF) survey—three of the most widely cited sources of data for youth vaping.[5,6,7]
Mr. Wang questioned whether the process for ascertaining parental consent may bias the survey responses. Ascertaining parental consent among minors is a common and required practice in most jurisdictions. To the extent that young respondents may not have provided honest responses due to concerns about confidentiality, the likely impact would be to under-report smoking and vaping status. However, the recruitment process has not changed over the course of the study; thus, this is unlikely to account for the trends over time reported in our paper. In addition, the trends in the ITC Youth Tobacco and Vaping Surveys are very similar to the trends in vaping reported by national surveillance surveys in the US, Canada, [8,9,10] and England.
Regarding Mr. Wang’s assertion that “when asking participants quitting plans, it is better to clarify the quitting of traditional tobacco products or quitting nicotine products”, we can confirm that questions about intentions to quit and cessation were indeed asked separately for smoking and vaping. Thus, if a youth reported smoking cigarettes and vaping e-cigarettes, they would have been asked cessation-related questions in different sections of the survey for each of cigarettes and e-cigarettes/vaping.
Finally, Mr. Wang has noted seasonal variation in smoking and vaping rates. Despite some variations in the exact survey timing, the ITC Youth Tobacco and Vaping Surveys have been conducted over a similar time period in each year. For example, across the first three waves of the survey, 64%, 79% and 74% of surveys, respectively, were conducted in the month of August. As noted above, trends in vaping prevalence over time from the ITC surveys align very closely with other national surveys over the same period. With respect to specific findings reported in our Tobacco Control manuscript, we would not expect any material differences in levels of dependence, cessation-related outcomes or vaping brands due to the minor variation in data collection periods.
We hope this additional information will provide context for interpreting the study results and feedback on the manuscript.
1. Hammond D, Reid JL, Rynard VL, Fong GT, Cummings KM, McNeill A, Hitchman S, et al. Prevalence of vaping and smoking among adolescents in Canada, England, and the United States: repeat national cross sectional surveys. BMJ. 2019; 365: l2219. doi: 10.1136/bmj.l2219.
2. Hammond D, Rynard V, Reid JL. Changes in prevalence of vaping among youth in the United States, Canada, and England, 2017 to 2019. JAMA Pediatr. 2020;174(8):797-800. doi: 10.1001/jamapediatrics.2020.0901.
3. Published Erratum: Prevalence of vaping and smoking among adolescents in Canada, England, and the United States: repeat national cross sectional surveys. BMJ. 2020 Jul 10;370:m2579. doi: 10.1136/bmj.m2579.
4. Hammond D, Reid JL, Rynard VL, Burkhalter R. ITC Youth Tobacco and E-Cigarette Survey:
Technical Report – Wave 3 (2019). Waterloo, ON: University of Waterloo, 2020. http://davidhammond.ca/wp-content/uploads/2020/05/2019_P01P3_W3_Technica...
5. Park-Lee E, Ren C, Sawdey MD, et al. Notes from the Field: E-Cigarette Use Among Middle and High School Students — National Youth Tobacco Survey, United States, 2021. MMWR Morb Mortal Wkly Rep 2021;70:1387–1389. DOI: http://dx.doi.org/10.15585/mmwr.mm7039a4.
6. Hyland A, Kimmel HL, Borek N, on behalf of the PATH Study team. Youth and young adult acquisition and use of cigarettes and ENDS: The latest findings from the PATH Study (2013-2019). Society for Research on Nicotine & Tobacco Annual Conference, March 2020
7. Miech R, Johnston L, O’Malley PM, Bachman JG, Patrick ME. Trends in adolescent vaping, 2017-2019. N Engl J Med. 2019;381(15):1490-1491. doi:10.1056/NEJMc1910739.
8. Government of Canada. Detailed tables for the Canadian Student Tobacco, Alcohol and Drugs Survey 2016-17. Available from https://www.Canada.ca/en/health-Canada/services/canadian-student-tobacco...
9. Government of Canada. Canadian Tobacco, Alcohol and Drugs Survey (CTADS): Summary of Results for 2017. 2017. Available from https://www.Canada.ca/en/health-Canada/services/canadian-tobacco-alcohol....
10. Statistics Canada. Canadian Tobacco and Nicotine Survey, 2019. Available from https://www150.statcan.gc.ca/n1/daily-quotidien/200305/dq200305a-eng.htm.
11. Action on Smoking and Health UK. Use of e-cigarettes among young people in Great Britain, 2021. June 2021. Available from https://ash.org.uk/wp-content/uploads/2021/07/Use-of-e-cigarettes-among-...
There’s a published paper by Hammond and colleagues in 2019 using the same survey results, but there are some discrepancies.
1. The Table 2 of the 2019 paper, prevalence of vaping in 2018 for ever, past 30 days are 37.0% (1425), 14.6% (562) in Canada, 32.7% (1276), 8.9% (346) in England and 33.6% (1360), 16.2% (655) in the US, respectively. However, in this article’s Table 1, for vaping in the same year 2018 for ever, past 30 days are 33.2% (1275), 12.1% (463) in Canada, 33.1% (1283), 9.0% (351) in England and 33.1%(1336), 15.7% (635) in the US. More discrepancies can be found on cigarette smoking section as well. These numbers warrant further explanation particularly why numbers in Canada and the US decreased while numbers in England increased? Considering previous correction of numbers to the 2019 paper has raised serious concern among some readers, such timely clarification in this article will be very necessary.
2. The 2019 paper use the criteria of ≥15 days in past 30 days but the current paper adopts different criteria of ≥20 days in past 30 days, for both vaping and cigarette smoking. Further explanation is needed for such change.
Additionally, a few considerations on possible limitations of the paper’s findings:
1. Since the invitations were sent to nearly twice more parents than youth themselves according to the technical report, responds to survey questions might be biased because study has shown many...
1. Since the invitations were sent to nearly twice more parents than youth themselves according to the technical report, responds to survey questions might be biased because study has shown many parents are unaware of their children’s e-cigarette use. Young participants who receive the questionnaire from their parents, in suspicion of their parents might know, may be unwilling to fill out honestly.
2. A clearer definition of stop smoking/quitting. In Table 3, when asking participants quitting plans, it is better to clarify the quitting of traditional tobacco products or quitting nicotine products. As some youth may treat vaping itself as quitting and some may not, the survey result might therefore, be ambiguous.
3. Seasonality. Previous studies have indicated seasonal variations in the initiation of smoking among adolescents, Unsupervised time out of school during the first months of summer vacation is a period of increased smoking behavior. However, significantly lower rates during September were observed which seem to be related to the beginning of school. Survey for this study were conducted July/August in 2017, August/September in 2018 and 2019. As cross-sectional study only offers a snapshot of the situation, to conduct surveys at different months with fluctuating trends would inevitably lower the liability of the result.
 Hammond, D., Reid, J. L., Rynard, V. L., Fong, G. T., Cummings, K. M., McNeill, A., Hitchman, S., et al. (2019). Prevalence of vaping and smoking among adolescents in Canada, England, and the United States: repeat national cross sectional surveys. BMJ (Clinical Research Ed.), 365, l2219.
 Hammond D, Reid JL, White CM. ITC Youth Tobacco and E-Cigarette Survey:
Technical Report – Wave 3 (2019. Waterloo, ON: University of Waterloo, 2020. http://
 Wu T and Chaffee BW. Parental Awareness of Youth Tobacco Use and the Role of Household Tobacco Rules in Use Prevention. Pediatrics. 2020;146(5): e20194034
 Colwell, B., Ramirez, N., Koehly, L., Stevens, S., Smith, D. W., & Creekmur, S. (2006). Seasonal variations in the initiation of smoking among adolescents. Nicotine & Tobacco Research, 8(2), 239–243.