Table 2.

Examples of published studies showing more rapid declines in youth smoking coincident with the introduction of ENDS

Article	Location, Data	Pre-trend in cigarette smoking		Post-trend in cigarette smoking		Comments
		Year(s)	Annual Change	Year(s)	Annual Change
Levy et al. [14]	USA, MTF 12th grade	2004–2013	-4.6%	2014–2017	-14.1%	“Thus, the downward trend was more than three times greater in the vaping period” (14.1%) than the long-term trend (4.6%).
	USA, MTF 10th grade	2004–2013	-5.8%	2014–2017	-19.8%	“…more than three times the relative reduction in the vaping period (19.8%=5.8%+14.0%) than the preceding period (5.8%)”
	USA, NYTS high school	2000–2013	-8.2%	2014–2017	By -22.0%	“With the vaping period modelled as a simple reduction in smoking for the YRBS and NYTS analyses, we obtained a 52% lower past 30-day smoking rates in the vaping period for YRBS and a 22% reduction for NYTS”
	USA, YRBS high school	2003–2017	-6.2%	2014–2017	By -52.0%
Foxon & Selya [42]	USA, NYTS	1999–2009	Projected smoking prevalence in 2018: ~4.25%	2010–2018	Actual smoking prevalence in 2018: ~1.9%	Analyses compared actual data vs. counterfactual projections (based on pre-period trends) using exponential trend modeling.
Meza et al. [43]	USA, MTF 12th grade boys	2006–2012	-1.6%	2012–2019	-17.4%
	USA, MTF 10th grade boys	2005–2011	-0.7%	2011–2019	-17.9%
	USA, MTF 8th grade boys	1996–2011	-8.8%	2011–2019	-17.3%
	USA, MTF 12th grade girls	1997–2012	-7.2%	2012–2019	-17.5%
	USA, MTF 10th grade girls	1997–2012	-9.5%	2012–2019	-16.3%
	USA, MTF 8th grade girls	1991–1996	10.9%	1996–2019	-10.8%
Wagner & Clifton [44]	USA, American Lung association Tobacco Trend Brief	1990–2009	Projected smoking prevalence in 2019: ~12%	2010–2019	Actual smoking prevalence in 2019: ~6%	Analyses compared actual data vs. counterfactual projections (based on pre-period trends) using dynamical systems modeling.

Notes MTF: Montoring the Future. NYTS: National Youth Tobacco Survey. YRBS: Youth Risk Behavior Survey