TABLE 4—

Studies Included in the Systematic Review Exploring the Effect of the Exposure to Pictorial Warnings on Cigarette Packages on Attempt to Quit Smoking: 1993–2013

Author, Study Area, and Study Period	Design and Sample	Outcome Definition	Exposure Assessment	Analyses	Measure and Adjustment	Main Results	Quality,a Finding,b and Remarks
Hammond et al.,25 southwest Ontario, CAN, 2001–2002c	Prospective cohort; n = 432	Any attempt to quit smoking that lasted ≥ 24 h in 3 mo follow-up	Depth of cognitive processing of PWCP, 9 items (5-point Likert scale), Q exposure (reduction only)	Logistic regression	OR; no adjustment for attempt only (Q analyses)	23.1% attempted at follow-up	Fair, null
						Q1, Ref; Q2, OR = 1.21 (95% CI = 0.44, 3.36); Q3, 1.28 (0.46, 3.50); Q4, 1.37 (0.50, 3.70)	Increasing trend from Q2–Q4 of PWCP cognitive processing on attempt in nonadjusted quartile analyses
Christie and Etter,26 Switzerland, France, Belgium, 2001	Pre–post; n = 365	≥ 1 quit attempt lasting ≥ 24 h in prior 4 wk (yes–no)	3 wk after online survey 4 cig boxes (addiction, passive smoking, health risks, smell) were sent to smokers who used them ∼21 d; evaluation 1 mo after getting the boxes	χ2 test	Proportions; no adjustments	Pre–post change, quit attempt proportion, 27% vs 22%, P > .05; pre–post difference across boxes: passive smoking, −1%; health risk, −7%; bad breath, +2%; addiction, −15%*	Poor, null
							Addiction even decreased attempt proportion sig. after exposure
Hammond et al.,27 southwest Ontario, CAN, 2001–2002c	Prospective cohort; n = 432 followed	Cessation-related behavior (including attempt lasting ≥ 24 h in past 3 mo)	Avoidance (no vs covering, hiding, avoiding PWCP) and emotional reaction (Likert scale) for extent of fear and disgust at BL; assessment 9 mo after full PWCP implementation	Logistic regression	OR; adjusted for daily cigarettes, smoking years, intention to quit, prior quit attempts, gender, age, education	Avoidance: AOR = 0.86 (95% CI = 0.56, 1.32)	Poor, mixed
						Emotional reactions: AOR =  1.37 (95% CI = 1.15, 1.64)	Pooled outcome
Environics Research Group Ltd.,28 CAN, 2000–2004	Repeated survey; n = 1002 smokers	Times stopped smoking ≥ 24h in past y	Implementation of PWCP in January 2001; all brands in June 2001	None	Proportion; no adjustments	2000 (before PWCP), 60%; 2001 (1 y after), 60%; 2002, 67%; 2003, 67%; 2004, 65%	Fair, uncertain—report
Borland et al.,32 AUS, UK, CAN, US, 2002–2006	Survey-based cohort; wk 1–2 2371/6525 (attempt/total), wk 2–3 2138/5257, wk 3–4 1823/4439, wk 4–5 1273/3993	Attempt to quit for ≥ 24 h since prior wave since previous wave out of the total	In relation to PWCP: salience, 2 items (noticed, read, or looked past month); cognitive response, 3 items (made think of health risk, more likely to quit, think about quitting in next 6 mo); forgoing cigs (ever–never); avoiding (yes–no); 4 items (covering, keep of sight, using case, avoid labels)	Logistic regression	OR; adjusted for age, gender, income, country, education, daily cig, baseline quit intention	Point estimates in 4 waves:	Fair, mixed
						salience—waves 1–2, 1.02; waves 2–3, 0.96; waves 3–4, 0.97; waves 4–5, 0.97; cognitive—waves 2–3, 1.28;* waves 3–4, 1.14;* waves 4–5, 1.16; forgoing—waves 1–2, 1.38;* waves 2–3, 1.23;* waves 3–4, 1.42;* waves 4–5, 1.30;* avoidance—waves 1–2, 1.17*; waves 2–3, 1.09; waves 3–4, 1.03;* waves 4–5, 1.03	Only CAN and AUS had PWCP
Shanahan and Elliott,34 AUS, 2000 and 2008	Repeated survey; n = 822 in 2000, n = 670 in 2008; smokers	Tried to give up and have been successful for ≥ 1 mo or < 1 mo in past y	Implementation of PWCP in 2006	χ2 test	Proportions; no adjustments	For ≥ 1 mo: 18% in 2000 vs 24% in 2008 (sig)	Poor, positive
						For < 1 mo: 21% in 2000 vs 26% in 2008 (sig)	Cross-sectional surveys compared
Malouff et al.,39 AUS, no period reported	RCT; n = 48 followed	Stage change toward cessation (includes “action to quit such as stopping or decreasing use”)	27 exposed to text-only vs 29 exposed to text + PW; on computer screen once per week for 4 wk; stage toward cessation at baseline, end of trial (post exposure), 1 mo after (follow-up)	Two-way ANOVA	Mean stage-of-change score difference; adjusted for preexposure	Stage change (including action-to- quit stage): postexposure, 2.59 (text) vs 3.04 (PW), P = .04; follow-up, 2.67 (text) vs 2.92 (PW), P > .05	Poor, mixed
							Unclear whether attempt was included in “action to quit”
Azagba and Sharaf,42 CAN,1998–2008	Cohort panel; n = 1459 (6269 person-years)	Smokers tried to quit in past 6 mo (yes–no)	3 exposure definitions: positive to PWCP (started January 2001) if (1) ≥ July 2001, (2) ≥ December 2001, (3) January–December 2001	GEE (population-averaged marginal effects of PCWC)	Proportion, OR; adjusted for gender, age, education, income, marital and immigration status, job, residence, smoking bans, price, nicotine dependence	Attempt: 1998, 30.1%; 2000, 34.6%; 2002, 40.2%; 2004, 33.1%; 2006, 34.6%; 2008, 29.6%	Fair, positive
			Scale 0–1 (January–June = 0, July = 0.1, August = 0.3, September = 0.5, October = 0.7, November = 0.9, December = 1.0)			All, ≥ July 2001, OR = 1.32 (95% CI 1.18, 1.49); January–December 2001, OR = 1.33 (95% CI 1.18, 1.49)	Population average effect rather than individual
						Daily smokers: ≥ December 2001, OR = 1.33 (95% CI 1.17, 1.50); January–December 2001, OR = 1.33 (95% CI 1.17, 1.50)
Thrasher et al.,44 Mexico, 2010–2012	Retrospective-like cohort; n = 1765	Attempt to quit in previous year, but after PWCP was implemented	Exposure (recall of having seen): PWCP (introduced September 25, 2010), media (only October 2010), PWCP + media (none); warnings were shown to assess recall (data collected from October 17, 2010–November 30, 2012)	Logistic regression	Proportion, OR; adjusted for age, income, civil status, education, gender, quit intention, smoking intensity, PWCP or media exposure	OR (95% CI; % attempt during study period): no recall of exposure, Ref (6%); PWCP, 4.23 (2.05, 8.69; 17%); media, 1.85 (0.81, 4.21; 9%), PWCP and media, 1.63 (0.75, 3.54; 9%)	Poor, positive
							No effect of media, or PWCP and media; variable duration of exposure, based on cross-sectional data

Note. ANOVA = analysis of variance; AOR = adjusted odds ratio; AUS = Australia; BL = baseline; BLrisk = baseline risk; C = control; CAN = Canada; CI = confidence interval; cig = cigarette(s); GEE = generalized estimating equations; ITC =  International Tobacco Control; PW = pictorial warning; PWCP = pictorial warnings on cigarette packages; OR = odds ratio; Q = quartile; RCT = randomized clinical trial; SA = self-affirmation; sig = statistically significant.

^aBased on the total sum of points for study design (2 = RCT, 1 = cohort, 0 = other designs), outcome definition (2 = clear and complete, 1 = unclear or incomplete, 0 = unclear and incomplete), exposure definition (2 = appropriate PWCP, 1 = appropriate warning intended for printing or inappropriate PWCP, 0 = inappropriate warning), and statistical analyses (2 = pertinent or adjusted, 1 = not pertinent or unadjusted, 0 = not pertinent and unadjusted); studies were classified as of very poor (0–2), poor (3–4), fair (5–6), and good (7–8) quality.

^bAccording to the most relevant finding. Positive: statistically significant effect (P < .05) regardless of the association strength; null = no significantly positive effect; mixed = either positive or null results observed; and uncertain = results available precluded a meaningful conclusion.

^cArticles used similar or identical data for analyses.

*Significant on the basis of 95% CI or P < 0.05.