Ll etal itc 4 pos warnings and quitting-addiction_published

RESEARCH REPORT doi:10.1111/j.1360-0443.2011.03668.x

The association between exposure to point-of-sale
anti-smoking warnings and smokers’ interest in
quitting and quit attempts: findings from the
International Tobacco Control Four Country Survey add_3668 425..433

Lin Li1, Ron Borland1, Hua-Hie Yong1, Sara C. Hitchman2, Melanie A. Wakefield3,
Karin A. Kasza4 & Geoffrey T. Fong2,5
VicHealth Centre for Tobacco Control, Cancer Council Victoria, Melbourne, Victoria, Australia,1 Department of Psychology, University of Waterloo, Waterloo,
Ontario, Canada,2 Centre for Behavioural Research in Cancer, Cancer CouncilVictoria, Melbourne,Victoria,Australia,3 Division of Cancer Prevention and Population
Sciences, Roswell Park Cancer Institute, Buffalo, NY, USA4 and Ontario Institute for Cancer Research, Toronto, Ontario, Canada5

ABSTRACT

Aims This study aimed to examine the associations between reported exposure to anti-smoking warnings at the
point-of-sale (POS) and smokers’ interest in quitting and their subsequent quit attempts by comparing reactions in
Australia where warnings are prominent to smokers in other countries. Design A prospective multi-country cohort
design was employed. Setting Australia, Canada, the United Kingdom and the United States. Participants A total of
21 613 adult smokers who completed at least one of the seven waves (2002–08) of the International Tobacco Control
Four Country Survey were included in the analysis. Measurements Reported exposure to POS anti-smoking warnings
and smokers’ interest in quitting at the same wave and quit attempts over the following year. Findings Compared to
smokers in Canada, the United Kingdom and the United States, Australian smokers reported higher levels of awareness
of POS anti-smoking warnings, and this difference was consistent over the study period. Over waves in Australia
(but not in the other three countries) there was a significantly positive association between reported exposure to
POS anti-smoking warnings and interest in quitting [adjusted odds ratio = 1.139, 95% confidence interval (CI)
1.039–1.249, P < 0.01] and prospective quit attempts (adjusted odds ratio = 1.216, 95% CI 1.114–1.327, P < 0.001)
when controlling for demographics, smoking characteristics, overall salience of anti-smoking information and aware-
ness of anti-smoking material from channels other than POS. Conclusions Point-of-sale health warnings about
tobacco are more prominent in Australia than the United Kingdom, the United States or Canada and appear to act
as a prompt to quitting.

Keywords Australia, Canada, health warnings, longitudinal research, point-of-sale, smoking cessation, survey,
United Kingdom, United States.

Correspondence to: Lin Li, VicHealth Centre for Tobacco Control, the Cancer Council Victoria, 100 Drummond Street, Carlton, Victoria 3053, Australia.
E-mail: lin.li@cancervic.org.au
Submitted 10 April 2011; initial review completed 30 June 2011; final version accepted 22 September 2011

INTRODUCTION tobacco industry in the United States has spent the vast
majority of their promotional budget in the retail envi-
Increasing numbers of countries have acted to restrict/ ronment over the past decade [9]. This ranges from
ban tobacco advertising and promotion in traditional promotional material to payments for shelf space and
media such as television, radio, print and on billboards incentive schemes for retailers.
[1–5]. The tobacco industry has responded by expanding A number of jurisdictions have banned POS tobacco
their marketing in areas where it is still allowed [6,7]. advertising, and some are now moving to prohibit the
Point-of-sale (POS) tobacco promotion has become an display of tobacco products—putting tobacco products
important marketing channel for the tobacco industry, as under the counter. Regardless of these restrictions, there
other marketing opportunities have been banned [8]. The are good reasons for having prominent POS anti-smoking

© 2012 The Authors, Addiction © 2012 Society for the Study of Addiction Addiction, 107, 425–433

426 Lin Li et al.

Figure 1 An example of Australian point-
of-sale anti-smoking warnings (notes: this
picture was taken in a supermarket in New
South Wales during the study period;
source: Simon Chapman of University of
Sydney and Anne Jones of Action on
Smoking and Health Australia)

warnings. This is the time when smokers purchase ciga- Warnings at the POS are less prominent in the other
rettes, so it should be a critical time to have them thinking countries. Some provinces of Canada started to mandate
about the harms. However, there is little empirical evi- POS warnings from around 2004/05 [15,16], but most
dence to support such initiatives. do not have size requirements. Pictorial warnings at the
During the study period (2002–08), Australia had POS were only introduced in some provinces of Canada
notably stronger POS anti-smoking warnings than did (e.g. British Columbia) from early 2008. In the United
the other three countries in the study (Canada, the United Kingdom, the Tobacco Advertising and Promotion (Point
Kingdom and the United States). Australia has had of Sale) Regulations 2004 allowed only one A5-sized
prominent POS warnings for some time, but with some (14.8 ¥ 21 cm) poster advertising tobacco in store with
variation across states. For example, the most populous 30% of that area taken up with a health warning (e.g.
state of New South Wales requires a health warning ‘smoking seriously harms you and others around you’,
message (e.g. ‘smoking is addictive’) and a Quitline in force from December 2004) [17]. The United States
number (131 848) that features: (i) black writing on a has no systematic requirements for POS anti-smoking
white background; and (ii) between 50 and 100 cm wide information.
and have an area not less than 2000 cm2 [10] (See We expected an overall higher level of awareness of
Fig. 1). In the second most populous state of Victoria, POS warnings in Australia, and given the improvements
similar warnings are mandated near the POS or at the in regulations regarding POS warnings over the study
shop entrance. However, they are smaller in Victoria [A4 period, increases in awareness in Australia, Canada and
in size (21 ¥ 29.7 cm)] [11]. In Queensland, under the the United Kingdom over-time. We were also interested in
Tobacco and Other Smoking Products Amendment Act determining if reported awareness of POS warnings were
2004, from December 2005 all the retail outlets are associated with higher quitting interest and prospectively,
required to display mandatory POS anti-smoking signs with higher levels of quitting activity, and whether this
that encourage quitting. Two other states (South Austra- varied by country (in this case a proxy for warning
lia and Western Australia), that began the 2002–08 strength).
study period with weaker signs, strengthened them to be
similar to those of New South Wales and Victoria during
the study period. METHODS
In Australia, POS anti-smoking warnings have been
Data source and participants
integrated with other health communication strategies,
such as mandating health warnings on cigarette packets The data come from the ﬁrst seven waves of the Interna-
and ongoing mass media campaigns that all have empha- tional Tobacco Control Four Country Survey (the ITC-4
sized the health harms of smoking and promoted the Survey), which has been running annually since 2002
Quitline number, sometimes using the same base mate- in Australia, Canada, the United Kingdom and the
rials [12–14]. United States. A detailed description of the conceptual


Association between POS warnings and quitting interest and attempts 427

framework and methods of the ITC-4 Survey has been Measures
reported by Fong et al. and Thompson et al. [18,19], and
The ITC-4 Survey included questions about smoking
more detail is available at http://www.itcproject.org.
behaviour, cigarette brand information, quit history,
Briefly, the ITC-4 Survey employs a prospective multi-
exposure to anti-tobacco advertising, psychosocial mea-
country cohort design and involves annual telephone
sures and demographics.
surveys of representative cohorts of adult smokers in
each of the four countries. The sampling is conducted via
random-digit dialling. The sample size per country is
Outcome measures
approximately 2000. At each survey wave, the approxi-
mately 30% lost to follow-up are replenished from the The key outcomes were interest in quitting and quit
same sampling frame. attempts. Interest in quitting was assessed by: ‘Are
Participants were aged 18+ years, had smoked at least you planning to quit smoking?’. Response options were
100 cigarettes life-time and had smoked at least once in ‘within the next month’, ‘within the next 6 months’,
the past 30 days at the time of recruitment. A total of ‘some time in the future, beyond 6 months’, ‘not planning
21 613 respondents who provided complete information to quit’ and ‘don’t know’. The first three categories were
for at least one of the seven waves (between 2002 and recoded to ‘having some interest in quitting’ and the
2008) were included in the analysis. The sample size for remaining as ‘not having an interest’. Quit attempts were
each country, the numbers of recruits in each wave/year, assessed at the next wave based on the answer to: ‘Since
and their characteristics are summarized in Table 1. we last talked to you [in last survey date], have you made

Table 1 Sample characteristics, by country.

Australia Canada United Kingdom United States Total

n = 4806 n = 5265 n = 5251 n = 6291 n = 21 613

Gender (% female) 53.5 53.7 55.8 55.1 54.6
Identified minority group (%) 12.8 11.3 4.9 20.3 12.7
Age at recruitment (years) (%)
18–24 14.2 12.8 8.5 11.7 11.7
25–39 35.6 30.3 31.3 26.3 30.6
40–54 34.0 36.5 33.8 36.6 35.3
55+ 16.1 20.4 26.4 25.5 22.4
Education at recruitment (%)a
Low 64.1 48.6 60.6 45.8 54.1
Moderate 21.9 36.4 25.1 38.3 30.9
High 13.9 14.8 13.5 15.9 14.6
Income at recruitment (%)a
Low 26.9 28.3 31.1 36.9 31.2
Moderate 32.7 34.4 31.5 33.3 33.0
High 34.0 28.4 27.6 22.7 27.8
No information 6.5 8.9 9.8 7.1 8.1
Cigarettes per day at recruitment (%)
1–10 29.8 31.4 29.8 31.1 30.6
11–20 40.1 42.7 53.4 45.8 45.6
21–30 22.8 21.1 11.7 13.1 16.9
31+ 7.1 4.4 4.8 9.4 6.6
No. of new recruits in each wave (n)
Wave 1 (in 2002) 2305 2214 2401 2138 9058
Wave 2 (2003) 258 517 255 684 1714
Wave 3 (2004) 532 545 586 889 2552
Wave 4 (2005) 362 519 503 742 2126
Wave 5 (2006) 686 594 613 745 2638
Wave 6 (2007) 539 556 523 711 2329
Wave 7 (2008) 142 320 370 382 1196

Percentages are based on unweighted data. For some variables the number of cases were fewer than the total, due to some ‘don’t know’ and ‘missing’
cases. aFor the definition of each category please see the Measures section.


428 Lin Li et al.

any attempts to stop smoking?’, or if a respondent stated Cigarettes per day (CPD) was asked at each wave and
that s/he had quit smoking since the previous survey recoded to: ‘already quit’, ‘1–10 CPD’, ‘11–20 CPD’ and
date. ‘21+ CPD’. Respondents were also asked at each wave
about their endorsement for regulation of tobacco pro-
ducts via the following statement: ‘Tobacco products
Measures of exposure to POS health warnings
should be more tightly regulated’. Response options
Respondents were asked at each wave about their notic- were ‘strongly agree’, ‘agree’, ‘neither agree nor dis-
ing of anti-smoking cues in a range of specific locations agree’, ‘disagree’ or ‘strongly disagree’.
or media, such as on television, radio, posters or bill-
Data analysis
boards. In this context the following question regarding
POS anti-smoking warnings was asked: ‘In the last 6 All analyses were conducted using STATA version 10.1.
months, have you noticed advertising or information that Both bivariate and multivariate analyses were conducted
talks about the dangers of smoking, or encourages quit- to examine (i) the association between reported exposure
ting, on store windows or inside stores where tobacco is to POS anti-smoking warnings and smokers’ interest in
sold?’. Those who answered ‘yes’ to this question were quitting in the same wave (i.e. cross-sectional associa-
regarded as having been exposed to POS warnings. tion) and (ii) the association between POS exposure and
subsequent quit attempts (i.e. longitudinal association, in
which quit attempts were measured one wave after the
Covariates
exposure to POS warnings). We first used c2 tests to look
A compound measure of exposure to anti-smoking warn- at the unadjusted association between POS exposure and
ings in places other than at the POS was created from quit interest/attempts for each wave, and then used mul-
the following eight items: exposure on television, radio, tivariate analyses to look at the fully adjusted association
movies, posters/billboards, newspapers/magazines, ciga- while considering data from all waves.
rette packs, leaflets and the internet (scores from 0–8). In Taking into consideration the correlated nature of the
addition, a measure of overall salience of anti-smoking data within people and across survey waves, we used the
information was used based on the following question: generalized estimating equations (GEE) approach to
‘In the last 6 months how often, if at all, have you noticed compute parameter estimates. All GEE models included a
anti-smoking information?’ (1, never; 2, rarely; 3, some- specification for an unstructured within-subject correla-
times; 4, often; 5, very often). tion structure, and parameter estimates were computed
Demographics measured included sex (male, female), using robust variance. Our large sample size allowed us
age at recruitment (18–24, 25–39, 40–54, 55 years and to assume an unstructured correlation structure in GEE
older) and identified majority/minority group, which was which helped us to estimate all possible correlations
based on the primary means of identifying minorities in between within-subject responses and included them in
each country (i.e. racial/ethnic group in the United the estimation of the variances. Both main outcomes
Kingdom, Canada and the United States; and English were dichotomous, so the GEE models included a specifi-
language spoken at home in Australia). Due to the differ- cation for the binomial distribution of the dependent
ences in economic development and educational systems variables. For the outcome of quit attempts a ‘forward’
across countries, only relative levels of income and edu- specification was used in the analysis so longitudinal
cation were used. ‘Low’ level of education referred to association was examined. In GEE modelling we first
those who completed high school or less in Canada, the explored the country effect and its interactions for
United States and Australia, or secondary/vocational or both outcome variables. Because country effect and its
less in the United Kingdom; ‘moderate’ meant commu- interaction were significant, we constructed separate
nity college/trade/technical school/some university GEE models for each country. In each of the models we
(no degree) in Canada and the United States, college/ included the following covariates: age, sex, ethnicity,
university (no degree) in the United Kingdom or baseline education, baseline income and also the follow-
technical/trade/some university (no degree) in Australia; ing time-varying covariates reported at each wave:
and ‘high’ referred to those who completed university or endorsement of regulation for tobacco products, overall
postgraduate studies in all countries. Household income salience of anti-smoking information, reported exposure
was also grouped into ‘low’ [less than $30 000 (country- to anti-smoking warnings in eight places other than POS
specific dollars) (£30 000 in the United Kingdom) per and cigarettes per day.
year], ‘moderate’ [$30 000–59 999 (£30 000–44 999
Ethics approval
in the United Kingdom)], and ‘high’ categories [equal
to or greater than $60 000 (£45 000 in the United The study protocol was approved by the institutional
Kingdom)]. review boards or research ethics boards of the University



of Waterloo (Canada), Roswell Park Cancer Institute 1.249, P < 0.01], in that those who were exposed to POS
(United States), University of Strathclyde (United warnings were 13.9% more likely at the same wave to
Kingdom), University of Stirling (United Kingdom), The report having quitting interest than those who were
Open University (United Kingdom) and The Cancer not exposed (Table 3). Similarly, in Australia those who
Council Victoria (Australia). were exposed to POS warnings at one wave were 21.6%
more likely to report having made quit attempts at the
next wave than those who were not exposed (adjusted
RESULTS
odds ratio = 1.216, 95% CI 1.114–1.327, P < 0.001,
Reported exposure to POS anti-smoking warnings by Table 4). No significant association between exposure
wave and country to POS warnings and outcomes was found in the other
three countries.
Figure 2 shows that smokers in Australia reported higher
levels of noticing POS anti-smoking warnings compared
to their counterparts in the other three countries, and
DISCUSSION
this was consistent over time. It is also notable that
the reported exposure to POS warnings in Australia POS anti-smoking warnings are designed to warn of the
increased over waves. There was also a smaller increase in dangers of smoking and encourage smokers to quit. This
the United Kingdom, but no clear evidence of an increase study shows clearly that the stronger, larger Australian
in either Canada or the United States. POS warnings are noticed and are associated with
increased interest in quitting and prospectively with quit
Interest in quitting and quit attempts by wave attempts for smokers in Australia. However, the weaker or
non-existent warnings in the other countries appear to
Table 2 provides the reported quitting interest and
have no measurable effects. In Australia, the positive
attempts over waves in each of the four countries. It can
association between exposure to POS warnings and out-
be seen that the proportions of reported interest in quit-
comes remained even when exposure to anti-smoking
ting were generally higher than those of quit attempts in
warnings in other domains and overall salience of anti-
all the countries. Those who were exposed to POS anti-
smoking information were controlled for.
smoking warnings were more likely to report having quit-
The findings raise two important questions. First, does
ting interest in Australia, but this was not the case in the
only finding a relation with quitting in Australia suggest
other three countries. Similar results were found for quit
some threshold effect, and secondly, how likely is it that
attempts with a positive effect in Australia and no clear
the relation we found for quitting are causal? The Austra-
pattern in the other three countries, although the pattern
lian warnings are required to be placed in prime POS
of significant results by year in Australia was less clear
positions—they are not incidental to signs promoting or
than for quitting interest (Table 2).
announcing tobacco sales, and they clearly promote the
Quitline number. They are typically at least A4 in size and
Associations between exposure to POS warnings and
black-on-white text, although there is variation between
quitting interest and attempts: GEE modelling results
states [12]. The small state of Tasmania now mandates
GEE modelling results show that over the waves in coloured graphic warnings using the same images as are
Australia (but not in the other three countries) there was on the cigarette pack warnings [20]), but the sample size
a significantly positive association between exposure is too small and the introduction too recent to be able to
to POS warnings and quitting interest [adjusted odds test for an independent effect of these warnings. The data
ratio = 1.139, 95% confidence interval (CI) 1.039– are clearly consistent with some threshold of exposure

100.0%
Percent(yes)

Figure 2 Noticing point-of-sale (POS) 50.0%
anti-smoking warnings in shops by wave
Australia
in International Tobacco Control Four 0.0%
Country Survey (ITC-4) countries (notes: W1- W2- W3- W4- W5- W6- W7- Canada
‘W1’ means ‘wave 1’ of the survey; this 2002 2003 2004 2005 2006 2007 2008 UK
applies to the other waves. Proportions Australia 39.3% 41.2% 42.4% 44.9% 52.4% 51.1% 57.8% US
reported here were based on weighted Canada 26.0% 21.1% 24.4% 24.9% 22.2% 21.2% 27.9%
data. A significant linear trend over years/
UK 14.1% 14.0% 16.6% 15.5% 17.6% 19.4% 21.2%
waves was found in Australia, but not in
the other three countries) US 18.6% 20.6% 21.8% 22.7% 22.0% 19.0% 23.5%


430 Lin Li et al.

Percentage of participants who reported having some intention to quit. Exposure and interest in quitting variables were from the same wave (i.e. cross-sectional association). bPercentage of participants who reported having made
that is related to warning message design and position.

at least one quit attempt between two consecutive surveys. Quit attempts occurred in the next wave/s after exposure (i.e. longitudinal association). ‘–’ stands for ‘not applicable’, because the wave 8 attempt data were not available
Not exposed
However, the failure to find any evidence of effects of the

64.9

72.9

57.9

68.5
newly introduced POS anti-smoking warnings in some
Wave 7 (2008)

–

–

–

–
Canadian provinces weakens the argument for a thresh-
old effect, and is more consistent with between-country
Exposed

71.7**

62.6*
74.8

70.9
differences. It is also consistent with their warnings not

–

–

–

–
evoking the broader anti-smoking efforts as do Australian
warnings. In other studies of the ITC-4 cohort, we have
Not exposed

not found between-country effects for the impact of
68.6
49.1

74.5
46.9

56.7
40.8

69.6
46.1
health warnings on cigarette packs [14], even though in
Wave 6 (2007)

the United States they are far smaller and less prominent
than in the other countries. One possibility for this
Exposed

77.6***
49.6

78.6
45.5

61.5
40.0

71.8
48.1
pattern of findings is that pack warnings are available
to smokers all the time, and smokers are prone to notice

at the time of writing. *Differences were significant at P < 0.05, Pearson’s c2 test (exposed versus not exposed; *is placed next to the higher figure); **P < 0.01; ***P < 0.001.
them from time to time, even when they are tucked away
Not exposed
Table 2 Reported interest in quitting and quit attempts over time, by country and exposure status to point-of-sale (POS) anti-smoking warnings.

on the side of the pack. By contrast, little time is spent in
69.8
46.7

75.1
42.6

60.1
41.3

71.2
44.7

stores, so they need to be prominent enough to be noticed
Wave 5 (2006)

with some regularity to have any real effect. This suggests
that POS warnings should be designed and placed in such
Exposed

76.7**

79.9**
46.1

74.4
41.9

40.5

71.2
41.6

a way that they are large and prominent enough to be
noticed.
One unique and relevant aspect of Australia’s
Not exposed

tobacco control programme is its comprehensiveness.
69.9*
70.9
47.5

76.2
42.8

63.9
41.1

40.3

It has integrated communications from mass-media
Wave 4 (2005)

campaigns, pack warnings and POS warnings. Recent
research into the different measures designed to reduce
Exposed

77.8**
50.6

75.8
43.4

66.9
39.0

64.2
43.4

smoking rates in Australia found that increases in
tobacco taxes and greater exposure to televised mass
media campaigns contributed to the decreased smoking
Not exposed

prevalence among Australian adults [21], and this is
72.2
41.9

77.2
42.9

63.0
44.9

69.2
41.1

consistent with international evidence showing that
Wave 3 (2004)

strong disease-related messages are potent motivators of
making quit attempts [8]. The overall broad and multi-
Exposed

77.5**
50.4**

74.9
43.0

58.0
44.1

69.0
47.2

location strategy of using the same prominent warnings
on the cigarette packs and at POS, as well as via mass
media would probably provide additional opportunities
Not exposed

for smokers to remember the warnings and this, in turn,
61.3*
72.3
41.9

80.7
43.9

38.3

72.0
38.9

might lead to an increase in the likelihood that the warn-
Wave 2 (2003)

ings would lead to action. Our data indicate that overall
salience of anti-smoking information was associated
Exposed

47.4*
75.6

80.3
46.5

54.3
34.3

68.4
44.7

with interest in quitting in all countries but Canada (for
reasons that are unclear) and quit attempts in Australia
and the United Kingdom. A recent study by Brennan
Not exposed

et al. [13] found that graphic health warnings on ciga-
65.5*
75.3
34.1

81.1
43.2

31.8

75.6
36.3

rette packets and on television operated in a complemen-
Wave 1 (2002)

tary manner to positively influence Australian smokers’
awareness of the health risks of smoking and motivation
Exposed

76.9
34.6

82.3
45.8

59.0
30.2

71.4
37.3

to quit [13], suggesting that such a multi-location strat-
egy may enhance effects. It is worth reflecting on the
fact that in most jurisdictions where POS is critical for
United Kingdom
%Attemptedb

%Attempted

%Attempted

%Attempted
% Intendeda

% Intended

% Intended

% Intended
United States

tobacco marketing, the POS pack displays have tradition-
ally served as a prompt for smokers to purchase tobacco
Australia

Canada

rather than avoid it, and to pose a risk for relapse for
those who have quit [22,23].
a



Table 3 Association between exposure to point-of-sale (POS) anti-smoking warnings and interest in quitting—generalized estimating
equation (GEE) modelling results.

Adjusted odds ratioa 95% CI P-value

Australia
POS warnings 1.139 1.039–1.249 <0.01
Seen in other health warning domains (number) 1.065 1.034–1.097 <0.001
Overall salience of anti-smoking information 1.090 1.052–1.129 <0.001
Canada
POS warnings 0.919 0.826–1.022 0.122
Overall salience of anti-smoking information 1.035 0.997–1.075 0.071
United Kingdom
POS warnings 1.014 0.908–1.132 0.806
United States
POS warnings 0.911 0.825–1.007 0.069

Exposure and intention variables were from same wave (i.e. cross-sectional association). Exposure to POS health warnings was coded as ‘1’ for ‘yes
exposed’, and ‘0’ for ‘not exposed’ (the referent). Main effect (not shown in table) for country and its interaction (exposure*country) was significant at
the P < 0.001 level, therefore separate models were constructed for each country. aAdjusted for gender, age, ethnicity, baseline education, baseline
income, endorsement for regulation of tobacco products at each wave, a compound measure of exposure to anti-smoking warnings in places other than
POS, overall salience of anti-smoking information, cigarettes per day at each wave, wave and cohort. CI: confidence interval.

Table 4 Longitudinal association between exposure to point-of-sale (POS) anti-smoking warnings and subsequent quit attempts—
generalized estimating equation (GEE) modelling results.

Adjusted odds ratioa 95% CI P-value

Australia
POS warnings 1.216 1.114–1.327 <0.001
Seen in other health warning domains (number) 0.995 0.968–1.023 0.718
Canada
POS warnings 0.909 0.820–1.007 0.067
United Kingdom
POS warnings 0.949 0.835–1.079 0.425
United States
POS warnings 0.987 0.900–1.082 0.774

Exposure to POS health warnings was coded as ‘1’ for ‘yes exposed’, and ‘0’ for ‘not exposed’ (the referent). ‘Having made quit attempts’ were measured
one wave AFTER the exposure to POS warning, and a ‘forward’ specification was used in the analysis. Main effect (not shown in table) for country and
its interaction (exposure*country) was significant at the P < 0.001 level, therefore separate models were constructed for each country. aAdjusted for
gender, age, ethnicity, baseline education, baseline income, endorsement for regulations of tobacco products at each wave, a compound measure of
exposure to anti-smoking warnings in places other than POS, overall salience of anti-smoking information, cigarettes per day at each wave, wave and
cohort. When interest in quitting was also adjusted for the effect remained essentially the same for each country, including the significant effect in
Australia. CI: confidence interval.


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