Journal of the New Zealand Medical Association, 20-January-2012, Vol 125 No 1348
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.
Survey—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
A 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
* 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.
This 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: email@example.com
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