This research capitalizes on a unique opportunity to study the relationship of SES and smoking cessation in four Western countries during a time of considerable policy change. It is also among the first to examine a spectrum of quitting outcomes, using longitudinal analysis. The findings indicate socioeconomic patterns in a number of cessation-related outcomes, including quit intentions, quit attempts, and varying lengths of smoking abstinence, as well as variations by country.
Although the majority of smokers in the four countries intended to quit at some point, there appears to be a substantial gap between intending to quit at all and committing to doing so in the near future. Smokers who say that they would like to quit sometime in the future may not be willing or ready to make a firm commitment to quitting, or they may be waiting for the right time or support.
Smokers with lower education or income were less likely to report intending to quit than those with higher education or income. The effects of SES variables were similar, and even slightly stronger, for intending to quit at all compared to within the next 6 months. When interactions were considered, the effects of income were modified somewhat by ethnicity and country: intentions to quit at all increased with income only for minority ethnicity respondents, and intentions to quit within the next 6 months were greater for higher income respondents in Canada and the United Kingdom only.
The current findings are consistent with studies documenting a relationship between intentions to quit and level of education (Dotinga et al., 2005
) and income (Fagan, Augustson, et al., 2007
). However, other studies have not found educational differences in intentions to quit (Droomers et al., 2004
; Reid et al., 2010
); this inconsistency may be due to differences in the samples, variable definitions, or study methods. Lower intentions to quit among lower socioeconomic groups may be due to lower levels of knowledge (Siahpush, McNeill, Hammond, et al., 2006
) or less concern about the harms of smoking, different attitudes and social norms around smoking and cessation (Dotinga et al.
; Manfredi, Cho, Crittenden, & Dolecek, 2007
; Rise, Kovac, Kraft, & Moan, 2008
; Sorensen, Emmons, Stoddard, Linnan, & Avrunin, 2002
), greater stress (Manfredi et al., 2007
; Stronks, van de Mheen, Looman, & Mackenbach, 1997
) and dependence on smoking to cope, lower self-efficacy for quitting (Dotinga et al.
; Droomers et al.
; Siahpush, McNeill, Borland, et al., 2006
), less social support (Sorensen et al., 2002
), or some other factors.
Intentions to quit also differed by country: Canadian smokers were the most likely to intend to quit, followed by Australians, while smokers in the United States and particularly the United Kingdom were less likely to intend to quit. In addition, although “any” intentions were not related to time, intentions to quit within the next 6 months were greater in the two most recent waves; this finding indicates that smokers’ commitments to quit strengthened in the past few years, potentially due to increased tobacco control activity and changing social norms in the four countries.
A substantial proportion of smokers surveyed had made a quit attempt since the last survey, but some socioeconomic variation was observed. Highly educated smokers were more likely to have made an attempt than those with low education, although quit attempts did not differ by income level. Income, however, interacted with a number of variables in the models (age, sex, country, and wave in the full sample analysis, and age and sex in the analysis of those who intended to quit), making its association with quit attempts difficult to characterize beyond its average effect across groups.
The effects of SES variables were the same for both the full sample and only those who intended to quit, suggesting that fewer attempts to quit among lower SES groups is not simply due to lower intentions to quit, and that SES differences exist independently for both intentions and attempts. SES differences in quit attempts may be due to the same factors underlying differences in intentions to quit. Access to cessation assistance and perceptions of its effectiveness (Hammond et al., 2004
; Roddy, Antoniak, Britton, Molyneux, & Lewis, 2006
) may also vary by SES and contribute to whether a smoker moves from intending to quit to making a quit attempt. These results are consistent with U.S. studies that have reported decreased likelihood of attempting to quit among lower education smokers, and inconsistent effects of income (Gilman et al., 2008
; Hatziandreu et al., 1990
; Levy et al., 2005
; Lillard et al., 2007
; Shiffman et al., 2008
). However, other studies in the United States, the United Kingdom, and Canada have found no SES differences in quit attempts (Barbeau et al., 2004
; Kotz & West, 2009
; Reid et al., 2010
; West et al., 2001
Differences in quit attempts between countries followed the same pattern as quit intentions, although with fewer significant findings: U.K. smokers were less likely to attempt to quit than Australians or Canadians in the full sample analysis, and U.S. respondents were also less likely to have attempted than Canadians in both samples. With respect to time, respondents were more likely to have made a quit attempt in more recent waves (compared with Wave 2); this is likely due to the shorter time period between Waves 1 and 2 compared with between the other waves.
Although direct comparisons with other studies are difficult due to varying study situations and definitions, abstinence rates in this study were relatively high (6-month rates of 8%, or 15% of those who attempted; and 12-month rates of 7%, or 12% of those who attempted) when compared with background unaided quit rates, which are estimated at 3% to 5% for 6–12 month abstinence after a given quit attempt (Hughes, Keely, & Naud, 2004
Success in remaining abstinent from smoking varied by education and income for 1-month abstinence and by education for 6-month abstinence, although 12-month abstinence was not related to either socioeconomic measure. More specifically, respondents with high education and income were 20%–30% more likely to quit for at least 1 month than those with low or moderate education and income. In addition, respondents with high education were 30% more likely to quit for at least 6 months compared with those with low or moderate education. The results suggest that lower quitting success among lower SES groups is not simply due to fewer smokers attempting to quit.
Previous findings regarding SES and cessation are mixed, with more studies showing a relationship with education and/or income than not, but with considerable variation in the significance and magnitude of such associations. This creates some difficulty for comparing the current study with existing literature. However, the findings for 1- and 6-month abstinence are consistent with studies showing an association of higher income and/or education with greater cessation success in the countries studied (Agrawal et al., 2008
; Barbeau et al., 2004
; Fagan, Shavers, et al., 2007
; Flint & Novotny, 1997
; Gilman et al., 2003
; Graham & Der, 1999
; Hymowitz et al., 1997
; Kotz & West, 2009
; Lillard et al., 2007
; West et al., 2001
, Wetter et al., 2005
Socioeconomic variation in 1- and 6-month abstinence may be affected by factors similar to those discussed for quit intentions and attempts: knowledge, attitudes and norms, stress, dependence, self-efficacy, and social support. In a study that also measured demographics, tobacco dependence, environmental and job-related characteristics, and transtheoretical model-based variables, there was an effect of education on smoking cessation regardless of the inclusion of any of these factors (Wetter et al., 2005
), suggesting that relationship of education and cessation may operate through other variables. Cessation differences may also be due to variation in social support (Droomers, Schrijvers, & Mackenbach, 2002
), quit methods, use of cessation assistance, and access to such assistance (Bobak et al., 2000
; Moolchan et al., 2007
The finding that SES variables were important for the shorter time periods but not 12-month abstinence may be due to the smaller and more select population eligible to be quit for two consecutive survey waves. Lower SES respondents and those who had quit were both more likely to be lost to follow-up, so the relationships observed between SES measures and longer term quitting may have been distorted. However, greater attrition among low-SES respondents alone would not likely result in the pattern of results observed unless a disproportionate number of those lost were continuing smokers (e.g., unless more low-SES quitters stayed in the sample), if in fact there were underlying differences by SES in smoking abstinence. The remaining sample may also be subject to some other selection bias. Alternately, SES differences in abstinence may diminish over time after a quit attempt; however, given the amount of existing research indicating that smokers of lower SES are less likely to quit, this is unlikely.
One notable country difference was observed in shorter-term abstinence: among those who had attempted to quit, respondents in the United Kingdom were more likely to be quit for at least 1 month and at least 6 months than those in other countries. So, although United Kingdom smokers were less likely to attempt to quit, those that did attempt were more successful at remaining abstinent. The higher abstinence rates observed among U.K. smokers may be due to the comprehensive smoking cessation services offered by their national health authority (Judge, Bauld, Chesterman, & Ferguson, 2005
Respondents’ odds of quitting increased over the 4-year survey period, particularly with respect to 6-month abstinence rates. This may be due to the greater length of time between surveys after Wave 2 and/or an actual increase in quitting over time in the population of smokers, potentially due to tobacco control activity.
Although this study has a number of strengths, including its large, representative samples of smokers from multiple countries and the ability to examine multiple outcomes and covariates over time, this analysis is subject to some general limitations common to survey research, such as attrition and potential biases in the sample, and reliance on self-report. The self-reported nature of the data introduces the possibility of reporting inaccuracies in the outcomes; for example, errors in recalling quit date or past-year quit attempts, potential bias toward recalling only successful or recent quit attempts, and the potential of social desirability to cause over-reporting of intentions to quit. Although these issues could lead to overestimating the prevalence of the outcomes, there is no reason to believe they would vary by SES, so the relationships between the outcomes and SES would not be affected. In addition, previous research has indicated that self-report of smoking behavior is generally accurate when compared with biochemical validation, particularly for observational studies (Patrick et al., 1994
Two SES measures, thought to measure unique aspects of SES, were tested in this study, strengthening its findings; however, each has limitations. An absolute measure of household income was used as a general indicator of material circumstances, although the adequacy of this income level depends on other factors such as household composition and or local cost of living.
As with all longitudinal studies, sample attrition is a concern. Preliminary analyses of between-wave attrition (data not shown) indicated that there are some significant relationships between attrition rates and several variables of interest. Attrition varied over time and by country and was greater among respondents who were younger, male gender, of minority ethnicity, had quit smoking, smoked less frequently, and who did not intend to quit. Of particular interest to the current study, moderate- and high-income respondents were more likely to remain in the sample (compared with those who did not provide income information) as were those with moderate education (at Waves 1 and 2), or high education (at Wave 3) (compared with those with low education levels). The patterns of attrition observed in this study are similar to others that have found greater attrition among respondents who were men, younger, less educated, and had lower income (Bull, Pederson, Ashley, & Lefcoe, 1988
; Psaty et al., 1994
). In this study, differential attrition by SES or other demographic characteristics would only change the findings if some characteristic(s) associated with attrition was also related to SES and the outcomes, thus distorting their relationship (e.g., if the lower SES respondents that dropped out of the study were different from those who stayed in the study in a way that is related to the outcomes). Any biases that may have been introduced into the proposed analysis by attrition are not quantifiable; however, such biases may be reduced by including the covariates associated with attrition in the analyses, and thus partially controlling for their impact. In addition, attrition could have decreased power in this study by decreasing the size of the sample available for analysis, leading to more conservative conclusions and estimates of the effect of income and education on the outcomes.