HEALTH PSYCHOLOGY, 1992,11(6), 413-417 Copyright © 1992, Lawrence Erlbaum Associates, Inc.
Stages of Readiness to Quit Smoking: Population Prevalence and Correlates Neville Owen University ofAdelaide
Melanie Wakefield South Australian Health Commission
Lyn Roberts
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Anti-Cancer Foundation of the Universities of South Australia
Adrian Esterman South Australian Health Commission We examined the population prevalence and correlates of stages in smokers' readiness to quit, using data from 1,048 smokers recruited in a self-weighting, multistage, systematic clustered area sample from 0.44% of South Australian dwellings, with an 89% response rate. Smokers in the precontemplation stage comprised 24.1% of the sample, smokers in the contemplation stage comprised 47.2%, and smokers in the preparation stage comprised 28.7%. No sociodemographic variables (i.e., age, sex, marital status, educational level) were found to be significant independent predictors of membership in the different stages. The five significant independent predictors of being in the precontemplation stage (vs. the contemplation stage) were (a) having a higher confidence of quitting, (b) seeing fewer healthrisksassociated with smoking, (c) not having made an attempt to quit, (d) seeing quitting as more difficult, and (e) smoking 25 or more cigarettes a day. The two significant independent predictors of being in the contemplation stage (vs. the preparation stage) were (a) having lower confidence of quitting and (b) not having tried to quit. We discuss implications for the understanding of smoking behavior in populations and also consider how cessation campaigns might address the factors associated with different stages of readiness to quit. Key words: smoking cessation, stages of change, readiness, predictors, confidence
The process of smoking cessation has been characterized as involving a set of stages, each having its particular characteristics (Best, 1978; Horn, 1967). The stage-of-change model developed by Prochaska and Di Clemente (1983; DiClemente et al., 1991) suggests that smokers can be in a precontemplation stage (in which quitting is not being considered), a contemplation stage (in which quitting is being considered), a preparation stage, or an action stage (in which they have recently quit). Accounts of change in other addictive behaviors use a similar set of stages (Brownell, Marlatt, Lichtenstein, & Wilson, 1986). Each of the stages of readiness to quit smoking may be affected differently by cessation campaigns: These interventions have a modest influence on maintained cessation (Flay, 1987; Pierce, Macaskill, & Hill, 1990), a greater influence on attempts to quit (Pierce et al., 1986), and an even greater influence on smokers' intentions to quit (Pierce, Dwyer, Chamberlain, Aldrich, & Shelley, 1987). Previous research, often with clinical or other self-selected samples, has most often examined the characteristics associated with the success or failure of actual cessation attempts and maintenance rather than with the earlier stages emphasised by the Prochaska and DiClemente model (precontemplation, contemplation, preparation). Such characteristics have included smoking rate (Borland, Owen, Hill, & Schofield, 1991; Kozlowski & Heafherton, 1990), efficacy expectations (Mothersill, McDowell, & Rosser, 1988), time to first cigarette (Fagerstrom & Schneider, 1989), and intention to quit (Pierce et al., 1987). The evidence on the role of previous quit Requests for reprints should be sent to Neville Owen, Department of Community Medicine, University of Adelaide, P.O. Box 498, Adelaide, South Australia 5001, Australia.
attempts is mixed: Cohen et al. (1989) found no relation between previous attempts to quit and subsequent success at cessation, whereas Borland et al. (1991) found that having made a previous quit attempt was negatively related to success at quitting. Risk perception has been argued to be an important influence on the adoption of smoking behavior (Best et al., 1984) and may also be related to readiness to attempt cessation. Added to these psychologically based variables are sociodemographic characteristics (age, gender, education, occupational status) that may be related to cessation. These characteristics have been found to be associated with differences in smoking prevalence and with the likelihood of being an ex-smoker (Hill, White, & Gray, 1991). Variables related to the earlier stages of readiness to quit have been examined to a lesser extent. DiClemente, Prochaska, and Gilbertini (1985) found higher levels of confidence about quitting among smokers at the more advanced stages of readiness to quit. DiClemente et al. (1991) found several significant differences among smokers in the precontemplation, contemplation, and preparation stages on aspects of current smoking behavior, history of quit attempts, confidence, and decisional-balance measures. Biener and Abrams (1991) differentiated these stages on the basis of a range of cessation-related variables. Accurate estimates of the population prevalence of stages of readiness to quit and the characteristics associated with membership in these stages in the general population are matters of some theoretical and practical interest. We used a representative sample to examine the prevalence of different stages in smokers' readiness to quit and also to determine the predictor variables that discriminated significantly between smokers in the precontemplation stage and those in the contemplation stage and between smokers in the contemplation stage and those in the preparation stage.
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METHOD The Australian Bureau of Statistics (ABS) conducted a population survey on behalf of the South Australian Smoking and Health Project between August and November 1989. It was a multistage, selfweighting, systematic, clustered area sample of 0.44% of South Australian dwellings, which resulted in a final sample of 3,767 persons age 15 years and older, weighted to the age and sex distribution of the 1989 population. Stage 1 of the sampling procedure was a computerized selection of census collectors' districts, selected with a probability proportional to their size; Stage 2 was a random selection of blocks within each census district, also selected with a probability proportional to their size; and Stage 3 was a systematic random selection of dwellings within each block. Up to five callback visits for urban residents and up to three call-back visits for rural residents resulted in a final response rate of 89%. The survey was conducted by personal interview in the home by trained interviewers from the ABS. It included a series of questions on smoking behavior and on knowledge of illnesses caused or aggravated by smoking, as well as questions on variables that previous research suggests may influence smoking cessation. The ABS pilot-tested the survey on 200 people, and items were subsequently revised and refined. Stage of change was assessed using an 11-point scale presented in the form of a ladder (Biener & Abrams, 1991), an instrument similar to that used in stage-of-change research on exercise (Marcus & Owen, in press) that found higher levels of readiness to exercise to be associated with greater confidence about exercising, and with different patterns of decisional balance. On the Biener and Abrams (1991) "Contemplation Ladder," 0 = No thought of quitting, 2 = Think I need to consider quitting someday, 5 = Think I should quit but not quite ready, 8 = Starting to think about how to change my smokingpatterns, and 10 = Taking action to quit (e.g., cutting down, enrolling in a program). It was also possible for respondents to indicate numbers between these main scale points as most applicable to them. Confidence (efficacy expectation) was assessed by asking "How confident are you that you could quit smoking in the next three months?" Response options were very confident, fairly confident, not at all confident, and not interested in quitting. Perceived difficulty of quitting was assessed by asking "How difficult do you think it would be to stop smoking?" Response options were very difficult, fairly difficult, not at all difficult, and never intend to stop. An index of the perceived health risks of smoking was constructed in the form of a continuous variable, based on the number of health problems (from a preset list of nine—including heart and lung diseases and some less serious health problems) that respondents believed to be related to smoking. An item from the Fagerstrom Tolerance Questionnaire (see Fagerstrom & Schneider, 1989)—which asked how soon after waking the first cigarette was smoked—was used as an index of nicotine dependency.
RESULTS Of the 3,767 persons interviewed, 1,048 were current smokers (27.8% overall prevalence: 32.1% for males, 23.6% for females). For the South Australian population, this represented a decrease in prevalence over the 2 years since the 1987 population survey (Owen & Davies, 1990), which found a 30% overall prevalence (34.7% for
males, 25.5% for females). This South Australian estimate is consistent with the findings of the national survey conducted in the same year (Hill et al., 1991).
Population Prevalence of Stages of Readiness to Quit The label No thought of quitting (Point 0) was endorsed by 24.1% of smokers (n = 248). Few respondents endorsed the nonlabeled points of the stage-of-change scale (1.8% endorsed Point 1, 1.1% endorsed Point 3, 1.8% endorsed Point 4, 2.6% endorsed Point 6, 2.6% endorsed Point 7, and 2.6% endorsed Point 9). Therefore, data were aggregated from the points in the stage-of-change scale that were not labeled to the major categories above and below that point. Think I need to consider quitting someday (Point 2, with data for Points 1 and 3 added) was endorsed by 18.2% of the smokers (n = 187), Think I should quit but not quite ready (Point 5, with data for Points 4 and 6 added) was endorsed by 29.0% (n = 299), Starting to think about how to change my smoking patterns (Point 8, with data for Points 7 and 9 added) was endorsed by 15.8% (n = 163), and Taking action to quit (e.g., cutting down, enrolling in a program) (Point 10) was endorsed by 12.9% (n = 132). We collapsed these five categories into three categories of readiness to quit, which were broadly consistent with, but not defined in precisely the same way as in the most recent version of, the Prochaska and DiClemente model (precontemplation, contemplation, preparation; DiClemente et al., 1991). The Biener and Abrams (1991) Contemplation Ladder, which we used, unlike the Prochaska and DiClemente assessment of stages, does not specify the next 6 months as the period in which quitting is being considered. Precontemplation smokers—No thought of quitting—comprised 24.1% of the sample (n = 248). Contemplation smokers—Think I need to consider quitting someday and Think I should quit but not quite ready—comprised 47.2% (n = 486). Preparation smokers— Starting to think about how to change my smoking patterns and Taking action to quit (e.g., cutting down, enrolling in a program)— comprised 28.7% (n = 295).
Variables Associated With Stages of Readiness to Quit Data for each of the potential predictor variables were converted to a categorical form (see Table 1). Using our three categories of readiness to quit (precontemplation, contemplation, preparation), we conducted a set of bivariate tests (chi-square with 2 df) for differences across these three categories on those variables that, on a priori grounds, may have been related to different stages of readiness to quit smoking. There were no statistically significant differences between the stages for sex or for marital status. Those variables on which significant differences across the stages emerged in the bivariate analyses were (a) being older, (b) smoking more cigarettes per day, (c) being in a low educational category, (d) not having made a previous attempt to quit, (e) smoking the first cigarette of the day within the first 30 min of waking, (f) seeing quitting as difficult, (g) having low confidence about quitting, and (h) identifying five or fewer risks (out of nine actual health risks) associated with smoking.
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READINESS TO QUIT SMOKING
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Independent Predictor Variables of Stages of Readiness to Quit Those variables on which significant differences emerged in the bivariate tests were entered into two separate logistic regression analyses. The first logistic regression treated the precontemplation stage (vs. the contemplation stage) as the dependent variable; the second logistic regression treated the contemplation stage (vs. the preparation stage) as the dependent variable. In the first logistic regression (precontemplation vs. contemplation; see Table 2), a model containing five variables provided a significant fit to the data (p < .0001). The significant independent predictors were (a) higher confidence of quitting, (b) seeing fewer health risks associated with smoking, (c) not having made a previous attempt to quit, (d) seeing quitting as more difficult, and (e) smoking 25 or more cigarettes a day. In the precontemplation stage, compared to those who had tried to quit, those who had not tried to quit were significantly more likely to see few health risks associated with smoking, % (1, N = 486) = 4.7, p < .05. On initial inspection, an anomaly appeared to exist in these data. In the bivariate analyses shown in Table 1, the apparent direction of the difference in perceived difficulty of quitting between precontemplators and contemplators is reversed for the corresponding multivariate comparison shown in Table 2. The bivariate comparison did not take into account correlations between variables; the multivariate comparisons did take this association into account. Thus, the apparent anomaly resulted from the strong negative correTABLE 1 Population Prevalence of Stages of Change Related to Smoking Cessation, and Variables Associated With the Stages
Prevalence at each stage Female Above median age of 33 years Not married or de facto Low education category Smokes 25 + cigarettes/day No previous quit attempt Nicotine dependence (smokes within 30 min of waking) Sees quitting as being very difficult Low confidence in ability to quit Sees few health risks
Precontemplation
Contemplation
24.1 37.9
47.2 45.3
28.7 46.2
59.6
47.6
41.5
44.8
44.7
40.0
54.1
44.3
43.7
31.8
26.7
22.3
47.2
21.3
16.3
46.4
39.2
27.8**
42.1
52.7
40.6**
29.0
55.7
36.6**
65.3
40.2
32.5**
Note. All numbers are percentages. *p < .05. **p < .01.
DISCUSSION The criterion that we used for membership in the precontemplation stage was more stringent than that used in previous studies, which have defined precontemplation as "no intention to quit smoking in the forseeable future"—commonly within the next 6 months (DiClemente et al., 1985; Prochaska & DiClemente, 1983). Our population prevalence for precontemplation (24%) is likely an underestimate, compared with what we might have found using a less restrictive criterion. We also found that 47% of smokers reported TABLE 2 Logistic Regression for Likelihood of Being at the Precontemplation Stage, as Opposed to the Contemplation Stage, of Quitting Smoking
SE ($)
Odds Ratio
95% Confidence Interval for Odds Ratio
1.53
0.22
0.22
0.14 to 0.34***
1.01
0.19
2.74
1.90 to 3.97***
0.94
0.20
2.57
1.74 to 3.78***
0.76
0.22
2.13
1.37 to 3.30**
0.43
0.21
1.54
1.01 to 2.34*
Predictor Variable
Stage Variable
lation between perceived difficulty of quitting and confidence about doing so (r = -.52, p < .001), which the multivariate comparison took into account when testing for the independent relations between perceived difficulty of quitting and stage of change. As a result, the logistic regression (Table 2) showed that, compared to contemplators, precontemplators were more likely to have a high perceived difficulty. In the second logistic regression (contemplation vs. preparation; see Table 3), a model containing two variables provided a significant fit to the data (p < .0001). These significant predictors, in order of the magnitude of the differences, were not being low in confidence about quitting and not having tried to quit.
Preparation
Low confidence in ability to quit Sees few health risks No previous quit attempt Sees quitting as being very difficult Smokes 25 + cigarettes/day
*p < .05. **p < .001. ***p < .0001.
TABLE 3 Logistic Regression for Likelihood of Being at the Contemplation Stage, as Opposed to the Preparation Stage, of Quitting Smoking
0
SEtf)
Odds Ratio
95% Confidence Interval for Odds Ratio
0.75
0.16
2.12
1.11 to 2.89**
0.51
0.21
1.66
1.49 to 2.48*
Predictor Variable Low confidence in ability to quit No previous quit attempt
*p < .01. **p < .0001.
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416
OWEN, WAKEFIELD, ROBERTS, ESTERMAN
that they were considering quitting (contemplation stage), which, given the stringency of our criterion for precontemplation, is likely an overestimate of the proportion who are considering quitting. However, it is not possible to make such comparisons, because population-prevalence data based on the more usual criterion are not yet available. Our stage-of-change instrument was the Contemplation Ladder, which Biener and Abrams (1991) reported using with a sample of smokers from a particular worksite. A comparison of populationprevalence estimates shows that 24.1% of the smokers in our study (vs. 9.5% in Biener & Abrams) were in precontemplation, 47.2% (vs. 56.4% in Biener & Abrams) were in contemplation, and 28.7% (vs. 34.1% in Biener & Abrams) were in preparation. Our representative population data show a clear trend for smokers to be in the less advanced stages of readiness to quit (mainly precontemplation) compared with what Biener and Abrams found. We found significant differences between the stages on dynamic variables but no differences on static variables such as gender—a pattern of findings broadly similar to DiClemente et al.'s (1991). Compared with smokers in the contemplation stage, smokers in the precontemplation stage were about 5 times less likely to be low in confidence of quitting; they were more than 2 times as likely to see fewer health risks to be associated with smoking, not to have tried to quit before, and to see quitting as difficult; they were V/i times more likely to smoke 25 or more cigarettes a day. Compared with smokers in the preparation stage, smokers in the contemplation stage were more than 2 times as likely to be low in confidence of quitting and more than 1 Vi times more likely to have not tried to quit. These data are from a representative population survey, allowing generalizations to be made about the overall population of smokers. There are some implications of the present findings for cessation campaigns that might, for example, devote more resources to smokers who state that they do not want to quit (the precontemplators— 24% of our sample). Precontemplators are a group at high risk of smoking-related health problems because they tend to smoke at a higher rate than do contemplators and those preparing to quit. Precontemplators are also those who are least convinced about the health risks associated with smoking. This lower level of perception of risk may not be related to denial or rationalization following failed cessation attempts because the precontemplators are also less likely to have ever tried to quit. Indeed, we found that, in the precontemplation stage, compared with those who had tried to quit, those who had not tried to quit were significantly more likely to see few health risks associated with smoking. Precontemplators may be genuinely ignorant about the health risks of smoking and thus may benefit from exposure to tailored information on the health risks of smoking and the gains to health of quitting. The precontemplators were significantly less likely than the contemplators to be low in confidence of quitting. The characteristics of the precontemplator subgroup (particularly their being less likely to have ever tried to quit, smoking at a higher rate, and seeing less risk associated with smoking) may make them unrealistically optimistic about their prospects of quitting if they were to make an attempt. Owen and Brown (1991) found that, compared with smokers who had ever made only one attempt, smokers who had made multiple attempts were significantly less likely to be confident of being able to quit successfully. They also saw cessation as more difficult and were more likely to see themselves as addicted. It might be argued that precontemplators ought not to be encouraged to make cessation attempts unless they are strongly committed to maintaining cessation
and are well prepared to do so. There is such an emphasis on committment and preparation for quitting in the Prochaska, Velicer, DiClemente, and Fava (1988) processes-of-change framework. Borland et al. (1991), in a prospective study of workplace smoking bans, found that smokers who reported that they had not tried to quit before were less likely to make a subsequent quit attempt, but, if they did, they were more likely to achieve sustained cessation. Confidence had a weak negative relation to making an attempt and was unrelated to the success of the attempt. Greater habit strength (a factor that included high smoking rate) had a negative relation to sustained cessation—a finding that is also consistent with Mothersill et al.'s (1988) and Pomerleau, Adkins, and Pertschuck's (1978). The Borland et al. (1991) findings, although dealing with smokers affected by a particular environmental context, do suggest that some of our predictors of being in the early stages of readiness to quit may also be related to action and maintenance. Contemplators made up 47% of our sample and so comprise a large potential target group for cessation campaigns. The only significant differences that we found between contemplators and smokers preparing to quit were that they were lower in confidence and were more likely to smoke 25 or more cigarettes a day. For contemplators, campaigns might use persuasive-communication strategies to enhance confidence of quitting and might also offer options of appropriate forms of personalised assistance to higher rate smokers (Owen & Davies, 1990). We carried out a cross-sectional study with data from a representative sample. Such population studies (Jeffery, 1989; Owen, 1989) allow generalizations to be made about all smokers, but there are inherent limitations to cross-sectional designs. Studies of readiness to quit smoking need to go beyond data on associations—to use designs that allow inferences about consequence and causality. Future research on stages in smoking cessation requires prospective study designs (DiClemente et al., 1991) and, ideally, trials of interventions tailored to the different stages of readiness to quit. Such research has the potential to further increase our understanding of the population-level dynamics of change in smoking behavior and can be of practical relevance to mass-reach cessation campaigns.
ACKNOWLEDGMENTS We thank the Anti-Cancer Foundation of the Universities of South Australia for funding support; the staff of the Statistical Services and State Projects Section of the Australian Bureau of Statistics (Adelaide Office) for the conduct of the survey; the Behavioural Epidemiology Unit of the South Australian Health Commission for assistance with development and organization of the survey; and David B. Abrams for initial advice on the use of the Contemplation Ladder.
REFERENCES Biener, L., & Abrams, D. B. (1991). The Contemplation Ladder: Validation of a measure of readiness to consider smoking cessation. Health Psychology, 10, 350-365. Best, J. A. (1978). Targeting and self-selection of smoking modification methods. In J. L. Schwartz (Ed.), Progress in smoking cessation (pp. 105-118). New York: American Cancer Society. Best, J. A., Flay, B. R., Towson, K. B., Perry, C. L., Brown, K. S., Kersell,
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
READINESS TO QUIT SMOKING M. W., & d'Avernas, J. R. (1984). Smoking prevention and the concept of risk. Journal ofApplied Social Psychology, 14, 257-273. Borland, R., Owen, N., Hill, D., & Schofield, P. (1991). Predicting attempts and sustained cessation of smoking after the introduction of workplace smoking bans. Health Psychology, 10, 336-342. Brownell, K. D., Marlatt, G. A., Iichtenstein, E., & Wilson, G. T. (1986). Understanding and preventing relapse. American Psychologist, 41, 765782. Cohen, S., Lichtenstein, E., Prochaska, J. O., Rossi, J. S., Gritz, E. R., Orleans, C. T., Schoenbach, V. J., Biener, L., Abrams, D., DiClemente, C, Curry, S., Marlatt, G. A., Cummings, K. M., Eamont, S. L., Giovino, G., & Ossip-Klein, D. (1989). Debunking myths about self-quitting: Evidence from 10 prospective studies of persons who attempt to quit smoking by themselves. American Psychologist, 44, 1355-1365. DiClemente, C. C , Prochaska, J. A., Fairhurst, S. K., Velicer, W. F., Velasquez, M. M., & Rossi, J. F. (1991). The process of smoking cessation: An analysis of precontemplation, contemplation, and preparation stages of change. Journal of Consulting and Clinical Psychology, 59, 295-304. DiClemente, C. C, Prochaska, J. A., & Gilbertini, M. (1985). Self-efficacy and the stages of self-change of smoking. Cognitive Therapy and Research, 9, 181-200. Fagerstrom, K. O., & Schneider, N. (1989). Measuring nicotine dependence: A review of the Fagerstrom Tolerance Questionnaire. Journal of Behavioral Medicine, 12, 159-182. Flay, B. R. (1987). Mass media and smoking cessation: A critical review. American Journal of Public Health, 77, 153-160. Hill, D. J., White, V., & Gray, N. (1991). Australian patterns of tobacco smoking in 1989. Medical Journal of Australia, 154, 797-801. Horn, D. (1967). A model for the study of personal choice health behavior. International Journal of the Addictions, 19, 89—98. Jeffery, R. W. (1989). Risk behaviors and health: Contrasting individual and population perspectives. American Psychologist, 44, 1194-1202. Kozlowski, L. T., & Heatherton, T. F. (1990). Self-report issues in cigarette
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smoking: State of the art and future directions. Behavioral Assessment, 12, 53-75. Marcus, B., & Owen, N. (in press). Self-efficacy, decision-making and the stages of exercise behavior change. Journal of Applied Social Psychology. Mothersill, K. J., McDowell, I., & Rosser, W. (1988). Subject characteristics and long term post-program smoking cessation. Addictive Behaviors, 13, 29-36. Owen, N. (1989). Behavioral epidemiology research and intervention studies to improve smoking-cessation services. Health Education Research, 4, 145-153. Owen, N., & Brown, S. L. (1991). Smokers unlikely to quit. Journal of Behavioral Medicine, 14, 627-636. Owen, N., & Davies, M. J. (1990). Smokers' preferences for assistance with cessation. Preventive Medicine, 19, 424—431. Pierce, J. P., Dwyer, T., Chamberlain, A., Aldrich, R. N., & Shelley, J. (1987). Targeting the smoker in an antismoking campaign. Preventive Medicine, 16, 816-824. Pierce, J. P., Dwyer, T., Frape, G., Chamberlain, A., Amin, A., & Quit for life Steering Committee. (1986). Evaluation of Sydney Quit for life: Vol. 1. Achievement of intermediate goals. Medical Journal of Australia, 144, 341-344. Pierce, J. P., Macaskill, P., & Hill, D. (1990). Long-term effectiveness of mass-media led anti-smoking campaigns in Australia. American Journal of Public Health, 80, 565-569. Pomerleau, O., Adkins, D., & Pertschuck, M. (1978). Predictors of outcome and recidivism in smoking cessation treatment. Addictive Behaviors, 1, 193-202. Prochaska, J. O., & DiClemente, C. C. (1983). Stages and processes of self-change of smoking: Towards an integrative model of change. Journal of Consulting and Clinical Psychology, 51, 390-395. Prochaska, J. O., Velicer, W. F., DiClemente, C. C, & Fava, J. (1988). Measuring processes of change: Applications to cessation of smoking. Journal of Consulting and Clinical Psychology, 56, 520-538.
Stages of Readiness to Quit Smoking: Population Prevalence and Correlates Neville Owen University ofAdelaide
Melanie Wakefield South Australian Health Commission
Lyn Roberts
This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Anti-Cancer Foundation of the Universities of South Australia
Adrian Esterman South Australian Health Commission We examined the population prevalence and correlates of stages in smokers' readiness to quit, using data from 1,048 smokers recruited in a self-weighting, multistage, systematic clustered area sample from 0.44% of South Australian dwellings, with an 89% response rate. Smokers in the precontemplation stage comprised 24.1% of the sample, smokers in the contemplation stage comprised 47.2%, and smokers in the preparation stage comprised 28.7%. No sociodemographic variables (i.e., age, sex, marital status, educational level) were found to be significant independent predictors of membership in the different stages. The five significant independent predictors of being in the precontemplation stage (vs. the contemplation stage) were (a) having a higher confidence of quitting, (b) seeing fewer healthrisksassociated with smoking, (c) not having made an attempt to quit, (d) seeing quitting as more difficult, and (e) smoking 25 or more cigarettes a day. The two significant independent predictors of being in the contemplation stage (vs. the preparation stage) were (a) having lower confidence of quitting and (b) not having tried to quit. We discuss implications for the understanding of smoking behavior in populations and also consider how cessation campaigns might address the factors associated with different stages of readiness to quit. Key words: smoking cessation, stages of change, readiness, predictors, confidence
The process of smoking cessation has been characterized as involving a set of stages, each having its particular characteristics (Best, 1978; Horn, 1967). The stage-of-change model developed by Prochaska and Di Clemente (1983; DiClemente et al., 1991) suggests that smokers can be in a precontemplation stage (in which quitting is not being considered), a contemplation stage (in which quitting is being considered), a preparation stage, or an action stage (in which they have recently quit). Accounts of change in other addictive behaviors use a similar set of stages (Brownell, Marlatt, Lichtenstein, & Wilson, 1986). Each of the stages of readiness to quit smoking may be affected differently by cessation campaigns: These interventions have a modest influence on maintained cessation (Flay, 1987; Pierce, Macaskill, & Hill, 1990), a greater influence on attempts to quit (Pierce et al., 1986), and an even greater influence on smokers' intentions to quit (Pierce, Dwyer, Chamberlain, Aldrich, & Shelley, 1987). Previous research, often with clinical or other self-selected samples, has most often examined the characteristics associated with the success or failure of actual cessation attempts and maintenance rather than with the earlier stages emphasised by the Prochaska and DiClemente model (precontemplation, contemplation, preparation). Such characteristics have included smoking rate (Borland, Owen, Hill, & Schofield, 1991; Kozlowski & Heafherton, 1990), efficacy expectations (Mothersill, McDowell, & Rosser, 1988), time to first cigarette (Fagerstrom & Schneider, 1989), and intention to quit (Pierce et al., 1987). The evidence on the role of previous quit Requests for reprints should be sent to Neville Owen, Department of Community Medicine, University of Adelaide, P.O. Box 498, Adelaide, South Australia 5001, Australia.
attempts is mixed: Cohen et al. (1989) found no relation between previous attempts to quit and subsequent success at cessation, whereas Borland et al. (1991) found that having made a previous quit attempt was negatively related to success at quitting. Risk perception has been argued to be an important influence on the adoption of smoking behavior (Best et al., 1984) and may also be related to readiness to attempt cessation. Added to these psychologically based variables are sociodemographic characteristics (age, gender, education, occupational status) that may be related to cessation. These characteristics have been found to be associated with differences in smoking prevalence and with the likelihood of being an ex-smoker (Hill, White, & Gray, 1991). Variables related to the earlier stages of readiness to quit have been examined to a lesser extent. DiClemente, Prochaska, and Gilbertini (1985) found higher levels of confidence about quitting among smokers at the more advanced stages of readiness to quit. DiClemente et al. (1991) found several significant differences among smokers in the precontemplation, contemplation, and preparation stages on aspects of current smoking behavior, history of quit attempts, confidence, and decisional-balance measures. Biener and Abrams (1991) differentiated these stages on the basis of a range of cessation-related variables. Accurate estimates of the population prevalence of stages of readiness to quit and the characteristics associated with membership in these stages in the general population are matters of some theoretical and practical interest. We used a representative sample to examine the prevalence of different stages in smokers' readiness to quit and also to determine the predictor variables that discriminated significantly between smokers in the precontemplation stage and those in the contemplation stage and between smokers in the contemplation stage and those in the preparation stage.
414
OWEN, WAKEFIELD, ROBERTS, ESTERMAN
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METHOD The Australian Bureau of Statistics (ABS) conducted a population survey on behalf of the South Australian Smoking and Health Project between August and November 1989. It was a multistage, selfweighting, systematic, clustered area sample of 0.44% of South Australian dwellings, which resulted in a final sample of 3,767 persons age 15 years and older, weighted to the age and sex distribution of the 1989 population. Stage 1 of the sampling procedure was a computerized selection of census collectors' districts, selected with a probability proportional to their size; Stage 2 was a random selection of blocks within each census district, also selected with a probability proportional to their size; and Stage 3 was a systematic random selection of dwellings within each block. Up to five callback visits for urban residents and up to three call-back visits for rural residents resulted in a final response rate of 89%. The survey was conducted by personal interview in the home by trained interviewers from the ABS. It included a series of questions on smoking behavior and on knowledge of illnesses caused or aggravated by smoking, as well as questions on variables that previous research suggests may influence smoking cessation. The ABS pilot-tested the survey on 200 people, and items were subsequently revised and refined. Stage of change was assessed using an 11-point scale presented in the form of a ladder (Biener & Abrams, 1991), an instrument similar to that used in stage-of-change research on exercise (Marcus & Owen, in press) that found higher levels of readiness to exercise to be associated with greater confidence about exercising, and with different patterns of decisional balance. On the Biener and Abrams (1991) "Contemplation Ladder," 0 = No thought of quitting, 2 = Think I need to consider quitting someday, 5 = Think I should quit but not quite ready, 8 = Starting to think about how to change my smokingpatterns, and 10 = Taking action to quit (e.g., cutting down, enrolling in a program). It was also possible for respondents to indicate numbers between these main scale points as most applicable to them. Confidence (efficacy expectation) was assessed by asking "How confident are you that you could quit smoking in the next three months?" Response options were very confident, fairly confident, not at all confident, and not interested in quitting. Perceived difficulty of quitting was assessed by asking "How difficult do you think it would be to stop smoking?" Response options were very difficult, fairly difficult, not at all difficult, and never intend to stop. An index of the perceived health risks of smoking was constructed in the form of a continuous variable, based on the number of health problems (from a preset list of nine—including heart and lung diseases and some less serious health problems) that respondents believed to be related to smoking. An item from the Fagerstrom Tolerance Questionnaire (see Fagerstrom & Schneider, 1989)—which asked how soon after waking the first cigarette was smoked—was used as an index of nicotine dependency.
RESULTS Of the 3,767 persons interviewed, 1,048 were current smokers (27.8% overall prevalence: 32.1% for males, 23.6% for females). For the South Australian population, this represented a decrease in prevalence over the 2 years since the 1987 population survey (Owen & Davies, 1990), which found a 30% overall prevalence (34.7% for
males, 25.5% for females). This South Australian estimate is consistent with the findings of the national survey conducted in the same year (Hill et al., 1991).
Population Prevalence of Stages of Readiness to Quit The label No thought of quitting (Point 0) was endorsed by 24.1% of smokers (n = 248). Few respondents endorsed the nonlabeled points of the stage-of-change scale (1.8% endorsed Point 1, 1.1% endorsed Point 3, 1.8% endorsed Point 4, 2.6% endorsed Point 6, 2.6% endorsed Point 7, and 2.6% endorsed Point 9). Therefore, data were aggregated from the points in the stage-of-change scale that were not labeled to the major categories above and below that point. Think I need to consider quitting someday (Point 2, with data for Points 1 and 3 added) was endorsed by 18.2% of the smokers (n = 187), Think I should quit but not quite ready (Point 5, with data for Points 4 and 6 added) was endorsed by 29.0% (n = 299), Starting to think about how to change my smoking patterns (Point 8, with data for Points 7 and 9 added) was endorsed by 15.8% (n = 163), and Taking action to quit (e.g., cutting down, enrolling in a program) (Point 10) was endorsed by 12.9% (n = 132). We collapsed these five categories into three categories of readiness to quit, which were broadly consistent with, but not defined in precisely the same way as in the most recent version of, the Prochaska and DiClemente model (precontemplation, contemplation, preparation; DiClemente et al., 1991). The Biener and Abrams (1991) Contemplation Ladder, which we used, unlike the Prochaska and DiClemente assessment of stages, does not specify the next 6 months as the period in which quitting is being considered. Precontemplation smokers—No thought of quitting—comprised 24.1% of the sample (n = 248). Contemplation smokers—Think I need to consider quitting someday and Think I should quit but not quite ready—comprised 47.2% (n = 486). Preparation smokers— Starting to think about how to change my smoking patterns and Taking action to quit (e.g., cutting down, enrolling in a program)— comprised 28.7% (n = 295).
Variables Associated With Stages of Readiness to Quit Data for each of the potential predictor variables were converted to a categorical form (see Table 1). Using our three categories of readiness to quit (precontemplation, contemplation, preparation), we conducted a set of bivariate tests (chi-square with 2 df) for differences across these three categories on those variables that, on a priori grounds, may have been related to different stages of readiness to quit smoking. There were no statistically significant differences between the stages for sex or for marital status. Those variables on which significant differences across the stages emerged in the bivariate analyses were (a) being older, (b) smoking more cigarettes per day, (c) being in a low educational category, (d) not having made a previous attempt to quit, (e) smoking the first cigarette of the day within the first 30 min of waking, (f) seeing quitting as difficult, (g) having low confidence about quitting, and (h) identifying five or fewer risks (out of nine actual health risks) associated with smoking.
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READINESS TO QUIT SMOKING
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Independent Predictor Variables of Stages of Readiness to Quit Those variables on which significant differences emerged in the bivariate tests were entered into two separate logistic regression analyses. The first logistic regression treated the precontemplation stage (vs. the contemplation stage) as the dependent variable; the second logistic regression treated the contemplation stage (vs. the preparation stage) as the dependent variable. In the first logistic regression (precontemplation vs. contemplation; see Table 2), a model containing five variables provided a significant fit to the data (p < .0001). The significant independent predictors were (a) higher confidence of quitting, (b) seeing fewer health risks associated with smoking, (c) not having made a previous attempt to quit, (d) seeing quitting as more difficult, and (e) smoking 25 or more cigarettes a day. In the precontemplation stage, compared to those who had tried to quit, those who had not tried to quit were significantly more likely to see few health risks associated with smoking, % (1, N = 486) = 4.7, p < .05. On initial inspection, an anomaly appeared to exist in these data. In the bivariate analyses shown in Table 1, the apparent direction of the difference in perceived difficulty of quitting between precontemplators and contemplators is reversed for the corresponding multivariate comparison shown in Table 2. The bivariate comparison did not take into account correlations between variables; the multivariate comparisons did take this association into account. Thus, the apparent anomaly resulted from the strong negative correTABLE 1 Population Prevalence of Stages of Change Related to Smoking Cessation, and Variables Associated With the Stages
Prevalence at each stage Female Above median age of 33 years Not married or de facto Low education category Smokes 25 + cigarettes/day No previous quit attempt Nicotine dependence (smokes within 30 min of waking) Sees quitting as being very difficult Low confidence in ability to quit Sees few health risks
Precontemplation
Contemplation
24.1 37.9
47.2 45.3
28.7 46.2
59.6
47.6
41.5
44.8
44.7
40.0
54.1
44.3
43.7
31.8
26.7
22.3
47.2
21.3
16.3
46.4
39.2
27.8**
42.1
52.7
40.6**
29.0
55.7
36.6**
65.3
40.2
32.5**
Note. All numbers are percentages. *p < .05. **p < .01.
DISCUSSION The criterion that we used for membership in the precontemplation stage was more stringent than that used in previous studies, which have defined precontemplation as "no intention to quit smoking in the forseeable future"—commonly within the next 6 months (DiClemente et al., 1985; Prochaska & DiClemente, 1983). Our population prevalence for precontemplation (24%) is likely an underestimate, compared with what we might have found using a less restrictive criterion. We also found that 47% of smokers reported TABLE 2 Logistic Regression for Likelihood of Being at the Precontemplation Stage, as Opposed to the Contemplation Stage, of Quitting Smoking
SE ($)
Odds Ratio
95% Confidence Interval for Odds Ratio
1.53
0.22
0.22
0.14 to 0.34***
1.01
0.19
2.74
1.90 to 3.97***
0.94
0.20
2.57
1.74 to 3.78***
0.76
0.22
2.13
1.37 to 3.30**
0.43
0.21
1.54
1.01 to 2.34*
Predictor Variable
Stage Variable
lation between perceived difficulty of quitting and confidence about doing so (r = -.52, p < .001), which the multivariate comparison took into account when testing for the independent relations between perceived difficulty of quitting and stage of change. As a result, the logistic regression (Table 2) showed that, compared to contemplators, precontemplators were more likely to have a high perceived difficulty. In the second logistic regression (contemplation vs. preparation; see Table 3), a model containing two variables provided a significant fit to the data (p < .0001). These significant predictors, in order of the magnitude of the differences, were not being low in confidence about quitting and not having tried to quit.
Preparation
Low confidence in ability to quit Sees few health risks No previous quit attempt Sees quitting as being very difficult Smokes 25 + cigarettes/day
*p < .05. **p < .001. ***p < .0001.
TABLE 3 Logistic Regression for Likelihood of Being at the Contemplation Stage, as Opposed to the Preparation Stage, of Quitting Smoking
0
SEtf)
Odds Ratio
95% Confidence Interval for Odds Ratio
0.75
0.16
2.12
1.11 to 2.89**
0.51
0.21
1.66
1.49 to 2.48*
Predictor Variable Low confidence in ability to quit No previous quit attempt
*p < .01. **p < .0001.
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OWEN, WAKEFIELD, ROBERTS, ESTERMAN
that they were considering quitting (contemplation stage), which, given the stringency of our criterion for precontemplation, is likely an overestimate of the proportion who are considering quitting. However, it is not possible to make such comparisons, because population-prevalence data based on the more usual criterion are not yet available. Our stage-of-change instrument was the Contemplation Ladder, which Biener and Abrams (1991) reported using with a sample of smokers from a particular worksite. A comparison of populationprevalence estimates shows that 24.1% of the smokers in our study (vs. 9.5% in Biener & Abrams) were in precontemplation, 47.2% (vs. 56.4% in Biener & Abrams) were in contemplation, and 28.7% (vs. 34.1% in Biener & Abrams) were in preparation. Our representative population data show a clear trend for smokers to be in the less advanced stages of readiness to quit (mainly precontemplation) compared with what Biener and Abrams found. We found significant differences between the stages on dynamic variables but no differences on static variables such as gender—a pattern of findings broadly similar to DiClemente et al.'s (1991). Compared with smokers in the contemplation stage, smokers in the precontemplation stage were about 5 times less likely to be low in confidence of quitting; they were more than 2 times as likely to see fewer health risks to be associated with smoking, not to have tried to quit before, and to see quitting as difficult; they were V/i times more likely to smoke 25 or more cigarettes a day. Compared with smokers in the preparation stage, smokers in the contemplation stage were more than 2 times as likely to be low in confidence of quitting and more than 1 Vi times more likely to have not tried to quit. These data are from a representative population survey, allowing generalizations to be made about the overall population of smokers. There are some implications of the present findings for cessation campaigns that might, for example, devote more resources to smokers who state that they do not want to quit (the precontemplators— 24% of our sample). Precontemplators are a group at high risk of smoking-related health problems because they tend to smoke at a higher rate than do contemplators and those preparing to quit. Precontemplators are also those who are least convinced about the health risks associated with smoking. This lower level of perception of risk may not be related to denial or rationalization following failed cessation attempts because the precontemplators are also less likely to have ever tried to quit. Indeed, we found that, in the precontemplation stage, compared with those who had tried to quit, those who had not tried to quit were significantly more likely to see few health risks associated with smoking. Precontemplators may be genuinely ignorant about the health risks of smoking and thus may benefit from exposure to tailored information on the health risks of smoking and the gains to health of quitting. The precontemplators were significantly less likely than the contemplators to be low in confidence of quitting. The characteristics of the precontemplator subgroup (particularly their being less likely to have ever tried to quit, smoking at a higher rate, and seeing less risk associated with smoking) may make them unrealistically optimistic about their prospects of quitting if they were to make an attempt. Owen and Brown (1991) found that, compared with smokers who had ever made only one attempt, smokers who had made multiple attempts were significantly less likely to be confident of being able to quit successfully. They also saw cessation as more difficult and were more likely to see themselves as addicted. It might be argued that precontemplators ought not to be encouraged to make cessation attempts unless they are strongly committed to maintaining cessation
and are well prepared to do so. There is such an emphasis on committment and preparation for quitting in the Prochaska, Velicer, DiClemente, and Fava (1988) processes-of-change framework. Borland et al. (1991), in a prospective study of workplace smoking bans, found that smokers who reported that they had not tried to quit before were less likely to make a subsequent quit attempt, but, if they did, they were more likely to achieve sustained cessation. Confidence had a weak negative relation to making an attempt and was unrelated to the success of the attempt. Greater habit strength (a factor that included high smoking rate) had a negative relation to sustained cessation—a finding that is also consistent with Mothersill et al.'s (1988) and Pomerleau, Adkins, and Pertschuck's (1978). The Borland et al. (1991) findings, although dealing with smokers affected by a particular environmental context, do suggest that some of our predictors of being in the early stages of readiness to quit may also be related to action and maintenance. Contemplators made up 47% of our sample and so comprise a large potential target group for cessation campaigns. The only significant differences that we found between contemplators and smokers preparing to quit were that they were lower in confidence and were more likely to smoke 25 or more cigarettes a day. For contemplators, campaigns might use persuasive-communication strategies to enhance confidence of quitting and might also offer options of appropriate forms of personalised assistance to higher rate smokers (Owen & Davies, 1990). We carried out a cross-sectional study with data from a representative sample. Such population studies (Jeffery, 1989; Owen, 1989) allow generalizations to be made about all smokers, but there are inherent limitations to cross-sectional designs. Studies of readiness to quit smoking need to go beyond data on associations—to use designs that allow inferences about consequence and causality. Future research on stages in smoking cessation requires prospective study designs (DiClemente et al., 1991) and, ideally, trials of interventions tailored to the different stages of readiness to quit. Such research has the potential to further increase our understanding of the population-level dynamics of change in smoking behavior and can be of practical relevance to mass-reach cessation campaigns.
ACKNOWLEDGMENTS We thank the Anti-Cancer Foundation of the Universities of South Australia for funding support; the staff of the Statistical Services and State Projects Section of the Australian Bureau of Statistics (Adelaide Office) for the conduct of the survey; the Behavioural Epidemiology Unit of the South Australian Health Commission for assistance with development and organization of the survey; and David B. Abrams for initial advice on the use of the Contemplation Ladder.
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