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| Journal of the New Zealand Medical Association,
20-January-2012, Vol 125 No 1348
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Hazardous patterns of alcohol use are relatively
common in smokers: ITC Project (New Zealand)
Nick Wilson, Deepa Weerasekera, Christopher W Kahler, Ron
Borland, Richard Edwards
Higher levels of alcohol use are associated with higher
levels of smoking1-5 and are also associated
with lower rates of quitting.6-10 For example,
one large prospective study, the ITC Four Country Survey, found that individuals
who regularly drank heavily had significantly lower rates of quitting smoking
than all other participants.11
In New Zealand there is also some literature on the
relationship between smoking and alcohol use. One national study reported that
smoking was clustered with hazardous alcohol use (high AUDIT scores) at almost
twice the expected level.12 A pooled analysis
of five New Zealand surveys found that smoking prevalence was higher with
increasing average daily volume of alcohol (and with increasing volume per
drinking session) for both Māori and non-Māori, but that the
difference in smoking prevalence across levels of alcohol volume was greater
among non-Māori.13 Also, a study of
tertiary students, found that increased AUDIT scores were associated with
smoking tobacco.14
Given this background and ongoing health sector and
government interest in addressing the tobacco epidemic in New
Zealand,15 we aimed to further describe alcohol
use patterns among smokers in this country.
MethodsSurvey—The ITC Project (New
Zealand arm) surveyed a nationally representative sample of adult smokers. This
study derives its sample from the New Zealand Health Survey (NZHS) which is a
national sample with boosted sampling of Māori, Pacific and Asian New
Zealanders. Out of the potential respondents in the NZHS, a total of 1376
completed a telephone questionnaire in Wave 1 in 2007/08, giving a response rate
of 56.4%. But when considering the NZHS response rate and willingness to further
participate, then the overall response rate was reduced further to 32.6%.
Measures—The questions around
alcohol use were asked in the NZHS with the first question being if they had had
an alcoholic drink in the previous 12 months. Respondents were then asked 10
questions about their alcohol use, covering the volume and frequency of alcohol
consumed, alcohol-related problems and abnormal drinking behaviour. These 10
questions were developed by the World Health Organization and comprise the
Alcohol Use Disorders Identification Test (AUDIT). As in the published NZHS
analyses, we used the international definition of hazardous drinking as an AUDIT
score of 8 or more.
For five respondents there were incomplete AUDIT scores
(one out of 10 questions incomplete for each). So we imputed the missing values
by first examining the responses for those respondents who had given the same
answers to the other nine questions (of the AUDIT score) and who belong to the
same age, sex and ethnicity groups. Then we randomly selected from those
responses of the matched respondents to impute the value for the missing
question.
Weighting and statistical
analyses—Weighting of the results was desirable given the
sampling design (e.g., boosted sampling of three ethnic groups in the NZHS), and
non-response for the NZHS and ITC Project Wave 1 survey. Detailed descriptions
of the weighting processes are detailed in an online
report.16
Univariate analyses included various socioeconomic
status measures covering small area deprivation (NZDep2006), individual
deprivation (NZiDep) and financial stress.17
The logistic regression analysis used the “enter” method for all key
variables and fits with a conceptual framework that assumed hierarchical
relationships between demographic and sociodemographic
factors.18 Model 1 included demographic
variables alone, and Model 2 included additional sociodemographic variables (the
two measures of deprivation and a measure of financial stress, all of which have
conceptual differences17).
All analyses were conducted in Stata software (version
10, Stata-Corp, College Station, TX) and all of the presented
results were weighted and adjusted for the complex sample design of the NZHS to
make the sample representative of all New Zealand smokers. Further details of
the methods (including response rates and weighting processes) are available in
online Methods
Reports16,17 and related
publications.19,20
ResultsA third (33.1%) of participants had a drinking pattern that
was considered hazardous at the time of the NZHS (i.e., AUDIT scores >=8).
Hazardous drinking was more prevalent among younger smokers, with the proportion
drinking hazardously declining with increasing age (Table 1).
Male smokers were significantly more likely to have a
hazardous drinking pattern, as were Māori and Pacific smokers (compared to
European/Others). There was no pattern by small area deprivation but there was a
non-linear association with individual deprivation. That is those with moderate
individual deprivation (scores of 1 to 4) had a more hazardous pattern than
either the least-deprived or most-deprived individuals.
Reporting one of two forms of financial stress was also
associated with more hazardous drinking (Table 1).
Table 1. Demographic and sociodemographic
characteristics of New Zealand smokers by pattern of hazardous alcohol use
(AUDIT score ≥ 8, with all the results weighted to adjust for the complex
sample design and non-response)
Note: *See an
online Methods Report for more detailed descriptions of all these
measures.17
The associations with high AUDIT scores that remained
statistically significant in the logistic regression analysis were the findings
for being a younger smoker, being male and being Māori (i.e., Model 2,
Table 2). Also Asians had significantly less hazardous drinking compared to
European/Others.
Table 2. Logistic regression analysis for
hazardous alcohol use (AUDIT ≥ 8) among New Zealand smokers
Notes:
* The adjusted odds ratios (aORs) represent the odds
for having an AUDIT score of ≥ 8 compared to < 8.
** This p-value not adjusted for complex sample
design.
DiscussionThis study found that a third of smokers had a drinking
pattern that was considered hazardous. When compared to the pattern for all
non-smoking New Zealand adults in the NZHS, smokers were much more likely to be
hazardous drinkers (i.e., 33.1% in smokers in our study versus 13.1% in NZHS
non-smokers). Such hazardous drinking is of concern given the evidence
suggesting it may impede successful smoking
cessation.11 But also alcohol and smoking
synergistically increase the risk of some cancers e.g., those of the oral
cavity, pharynx, larynx and oesophagus.21
The groups with the most hazardous drinking pattern were
younger smokers, male smokers and Māori smokers (in both the univariate and
multivariate analyses). Therefore such patterns may be contributing to both
gender and ethnic health inequalities associated with smoking-related disease
and in terms of cancer risk. Indeed, growing ethnic inequalities in cancer
mortality (Māori versus non-Māori) have been described in New
Zealand.22
One finding of note was that those with moderate
individual deprivation (scores of 1 to 4) had a more hazardous pattern than
either the least-deprived or most-deprived individuals. The reason for this is
unknown in the New Zealand setting, but it could relate to the most-deprived
group being less able to afford alcohol or having existing health problems which
limit scope for heavy drinking.
A strength of this study was its nationally representative
sample. The risk of social desirability bias should have been reduced by the
location of the alcohol questions in a large survey and with the use of
show-cards for these questions during the face-to-face interview in the NZHS.
A potential weakness is that this study involved a sample
which (due to non-participation in the NZHS and then in the ITC Project survey)
could have become less representative of the national population of smokers. It
is therefore possible that the weighting process (although sophisticated) may
not have fully adjusted for non-response bias, potentially affecting the
generalisability of the findings to all New Zealand smokers. Therefore such
analyses as our one should be repeated in the future with data from the
new-version of the NZHS where continuous data are collected (and especially
where respondents complete the episodic but more in-depth “tobacco
module” questions).
In 2010 the New Zealand Law Commission published a
comprehensive review on reducing alcohol-related
harm23 and a Parliamentary Select Committee
began examining options for reducing this harm in early 2011. Given the research
findings presented here and the international literature, it would seem prudent
for New Zealand policy makers to further consider the synergies between alcohol
use and smoking. In particular they could:
This pattern has also
been found in the US.30 Nevertheless, making
outdoor areas smokefree could be controversial (given only minority
smoker support19)—although it may be
generally favoured by non-smoking patrons who often sit outside hospitality
venues in New Zealand in summer and are exposed to secondhand smoke.
Nevertheless, as of January 2012 it appeared that
the above interventions are not substantively part of the alcohol-reform
legislation currently before the New Zealand Parliament. But since this draft
legislation will probably be considered further in the 2012 parliamentary term,
there is probably still scope for it to be strengthened. Financial pressures on
government may also move the case for increased alcohol tax up the political
agenda.
Overall, there appears to be a growing divergence between
tobacco control and alcohol control in New Zealand with recent years involving a
range of new tobacco control initiatives (e.g., multiple tobacco tax rises, a
law banning point-of-sale tobacco displays, extra support for quitting services,
smokefree prisons, and government commitment to a “Smokefree Nation
2025” goal).
In summary, it would appear that hazardous drinking patterns
are relatively common among New Zealand smokers. Yet if policy makers wish to
address such problems then there is scope for using proven interventions
relating to reducing heavy alcohol drinking.
Competing interests: Although we do
not consider it a competing interest, for the sake of full transparency we note
that some of the authors have undertaken work for health sector agencies working
in tobacco control.
Author information: Nick
Wilson1; Deepa
Weerasekera1; Christopher W
Kahler2; Ron
Borland3; Richard
Edwards1
1 Department of Public
Health, University of Otago, Wellington, New Zealand
2 Center for Alcohol and
Addiction Studies, Brown University, Providence, Rhode Island, USA
3 VicHealth Centre for
Tobacco Control, Melbourne, Australia
Acknowledgements: The ITC Project (NZ) team
thank: the interviewees who kindly contributed their time; the Health Research
Council of New Zealand which has provided the funding (grant 06/453); and our
other project partners (see: http://www.wnmeds.ac.nz/itcproject.html).
We thank Professor Tony Blakely and Dr Fiona Imlach Gunasekara for helpful
comments on draft versions of this article.
Correspondence: Dr Nick Wilson, Department
of Public Health, University of Otago – Wellington, Box 7343, Wellington
South, New Zealand. Fax: +64 (0)4 3895319; email: nick.wilson@otago.ac.nz
References:
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