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Effectiveness of a Computer-Tailored Smoking Cessation Program
A Randomized Trial
Jean-François Etter, PhD, MPH;
Thomas V. Perneger, MD, PhD
Arch Intern Med. 2001;161:2596-2601.
ABSTRACT
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Background From a public health perspective, prevention of cancer and cardiovascular
diseases requires effective smoking cessation programs that can be used on
a large scale.
Objective To test the effectiveness of a new computer-tailored smoking cessation
program vs no intervention.
Methods Randomized controlled trial, in the French-speaking part of Switzerland,
September 20, 1998, to December 31, 1999. Potential participants were randomly
selected from a general population register and recruited by mail. Daily cigarette
smokers who wished to participate (N = 2934) were randomized to either the
program or no intervention. A mean of 1.5 times per 6 months, participants
in the active arm received by mail a computer-tailored counseling letter based
on their answers to a questionnaire and stage-matched booklets. The counseling
letters were tailored to the participants' stage of change (categorized as
precontemplation [no intention of quitting smoking in the next 6 months],
contemplation [seriously considers quitting in the next 6 months], or preparation
[has decided to quit in the next 30 days]), level of tobacco dependence, self-efficacy,
and personal characteristics. The outcome measure was self-reported abstinence
(no puff of tobacco smoke in the past 4 weeks) 7 months after entry into the
program.
Results Abstinence was 2.6 times greater in the intervention group than in the
control group (5.8% vs 2.2%, P<.001). The program
was effective in "precontemplators" who were not motivated to quit smoking
at baseline (intervention vs control, 3.8% vs 0.8%; P
= .001) and was effective regardless of perceived difficulty in quitting smoking
at baseline.
Conclusions The program was effective in increasing smoking cessation rates. Because
it can reach a large number of smokers, this program can substantially contribute
to disease prevention at a population level.
INTRODUCTION
SMOKING IS the cause of more than 45% of all cancer deaths and of 90%
of all lung cancer deaths in the United States.1
Quitting smoking at age 30 avoids 90% of the subsequent risk of death from
lung cancer, but smokers who stop at age 50 or 60 also substantially reduce
their risk of developing lung cancer.2
Individualized counseling for smoking cessation is effective,3 but few smokers are willing to attend smoking cessation
clinics4 and many smokers do not receive smoking
cessation advice from their physician.5 Self-help
smoking cessation materials can reach large numbers of smokers but may lack
effectiveness.6 Computer technology and psychological
theory can be used to produce and disseminate effective individualized self-help
smoking cessation materials.7-9
Because individually tailored materials consider the relevant characteristics
of each participant, smokers may be more interested in reading these materials
and more likely to apply the advice included therein.10-11
Consequently, tailored materials may be more effective than those intended
for all smokers.6, 8, 10, 12-13
Researchers have tested the effectiveness of computer-tailored smoking cessation
programs, with positive7-9,14
and negative15-16 results.
Traditional smoking cessation programs target only the 5% to 20% of
smokers interested in quitting immediately,17
leaving most smokers without support. Interventions directed at smokers who
have no immediate intention of quitting are needed. Some smoking cessation
programs have been effective in such smokers, sometimes called "precontemplators"
and "contemplators,"16, 18 but
others have not.12 Other subgroups require
special attention. In particular, smoking prevalence increased among adolescents
during the 1990s,19-20 and smoking
cessation interventions have often been ineffective among adolescent smokers.15, 21 Finally, quitting smoking is particularly
difficult for highly tobacco-dependent smokers.22
The aim of this study was to test the effectiveness of a new computer-tailored
smoking cessation program in a general population setting. In particular,
we were interested in testing whether precontemplators, contemplators, teenagers,
and heavy smokers could be recruited in this program, and whether the program
increased quit rates in these smokers.
PARTICIPANTS AND METHODS
SETTING AND PARTICIPANTS
Sample-size calculations indicated that a sample of 2000 was necessary
to detect a difference in quit rates between 4% (control group) and 7% (intervention
group), with a confidence level of 95% and a power of 80%. Expecting a response
of 10%, we sent an invitation to participate in the study and the baseline
questionnaire to a representative sample of 20 000 residents aged 18
to 60 of the French-speaking part of Switzerland. Smoking prevalence in Switzerland
was 33% in 1997.23 Addresses were randomly
selected from a general population register. The purpose of the study, the
risk of being attributed at random to a no-intervention control group, and
the follow-up procedures were explained in the accompanying letter. Only daily
cigarette smokers were eligible for the study. Nonsmokers and smokers who
did not want to participate were asked to transmit the questionnaire to a
smoker. The Geneva, Switzerland, review board for research in public health
approved the trial.
STUDY DESIGN
Daily smokers who wished to participate in the trial were randomly assigned
to the intervention or control groups using a list of random numbers. A participant
flow chart is presented in Figure 1.
The follow-up questionnaire was sent out 6 months after receipt of the baseline
questionnaire, and nonrespondents received up to 6 reminder mailings.
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Flow chart of participants in the randomized controlled trial.
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INTERVENTION AND CONTROL GROUP PROCEDURES
The intervention consisted of personal counseling letters, composed
by a computer according to smokers' answers to a questionnaire, and of stage-matched
booklets. The baseline questionnaire was also used to produce the first counseling
letter. The intervention was based on the transtheoretical model of change,18, 24 the theory of planned behavior,25 theories of relapse prevention26
and tobacco dependence,27 Agency for Health
Care Policy and Research recommendations,28
and other relevant literature.29 The questionnaires,
counseling letters, and booklets were also based on extensive qualitative
research and pretests conducted in Swiss smokers and ex-smokers.30-32
The counseling letters were illustrated with cartoons and graphs, which were
also tailored to each smoker's responses. The program was tested in hundreds
of people for more than a year before the study was conducted.
The questionnaires used to produce the tailored counseling letters assessed
the participants' demographic characteristics, stage of change, level of tobacco
dependence, attitudes toward smoking, self-efficacy, use of self-change strategies,
and intention to use nicotine replacement therapy. A participant's stage of
change was categorized as precontemplation (no intention of quitting smoking
in the next 6 months), contemplation (seriously considers quitting in the
next 6 months), or preparation (has decided to quit in the next 30 days).24 We used validated scales to measure these variables.30-33
After returning the questionnaire, participants in the intervention
group received by mail an 8-page personal counseling letter and two 16-page
booklets corresponding to their current stage of change and to the next stage.
Two months and 4 months after entering the study, participants in the intervention
group were invited to answer a new tailored questionnaire to receive a new
counseling letter. On average, participants received counseling 1.5 times
per 6 months. Almost half of the participants (49%) received counseling only
once, 40% twice, and 11% 3 times or more.
After returning the baseline questionnaire, members of the control group
received a letter indicating that they had been attributed to that group.
We did not contact them again until the follow-up survey.
OUTCOME MEASURES AND STATISTICAL ANALYSES
The main outcome measure was 1-month abstinence (not having taken even
a puff of tobacco smoke—cigarette, cigar, pipe, or other— in the
past 4 weeks), which is the criterion recommended by the Food and Drug Administration
for assessing smoking cessation in clinical trials.34
We also assessed 1-week abstinence (no puff of tobacco smoke in the past 7
days), which is the criterion used in a recent guideline to assess smoking
cessation in randomized trials.35 In addition
to questions asked at baseline, the follow-up questionnaire also included
the quit date for ex-smokers. The program effectiveness was measured by the
ratio of proportions of baseline smokers who were abstinent at follow-up.
We used an intention-to-treat analysis, in which all persons absent at follow-up
were considered to be smokers.
Because time to follow-up differed between the 2 groups, we conducted
a time-failure analysis, using proportional hazards regression models, with
the quit date for ex-smokers as time of event and the return date of the questionnaire
as time of censoring. For nonrespondents, the date of censoring was set to
1 day after receipt of the last questionnaire.
We tested the effectiveness of the program in subgroups of participants,
stratifying by age, sex, educational level, stage of change, level of tobacco
dependence (number of cigarettes per day), perceived difficulty in quitting,
and past quit attempts. We used multivariate logistic regression models to
assess the effectiveness of the program after adjustment for baseline characteristics
of participants, and to identify independent predictors of smoking cessation.
We used  2 tests to compare proportions, t tests to compare means, and Cox proportional hazards regression models
for time-failure analyses.36
RESULTS
BASELINE CHARACTERISTICS AND FOLLOW-UP RATES
At baseline, the intervention and control groups were similar (Table 1). The sample included a substantial
proportion of smokers not yet ready to quit (precontemplators), but, on average,
smokers in this study were more motivated to quit smoking than a representative
sample of smokers in Geneva, comprising 74% precontemplators, 22% contemplators,
and 4% who were ready to quit.17
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Table 1. Baseline Characteristics of Study Participants*
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Follow-up rates were 76% in the intervention group and 92% in the control
group (P<.001, overall response of 84%). The median
time between the baseline and follow-up surveys was 7.1 months (25th, 50th,
and 75th percentiles in the intervention and control groups: 187, 208, and
260 days and 182, 191, and 211 days, respectively; P<.001).
Feedback from participants indicated that some members of the intervention
group were tired of our successive mailings, which probably explains why the
response rate was lower in this group.
ABSTINENCE RATES
At follow-up, assuming that all nonrespondents were smokers, the 4-week
abstinence was 2.6 times greater in the intervention than in the control group
(95% confidence interval [CI], 1.7-3.8) (Table 2). The 7-day abstinence was 8.0% in the intervention group
and 3.3% in the control group (P<.001). In time-to-event
analysis, the relative hazard of quitting smoking in the intervention group
was 2.1 (95% CI, 1.4-3.2). When this analysis was limited to the first 180
days following the baseline survey, the relative hazard was 2.2 (95% CI, 1.4-3.5).
After day 180, the relative hazard of quitting became nonsignificant (relative
hazard = 1.6; 95% CI, 0.6-4.3). Therefore, the between-group difference in
quit rates did not appear to be affected by the difference in time to follow-up.
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Table 2. Smoking Cessation Rates After 7 Months for Participants in
a Computer-Tailored Smoking Cessation Program and in a No-Intervention Control
Group
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Using the criterion of 4-week abstinence, the program produced 1 additional
quitter for every 28 participants. The program was as effective among men
as among women. It was effective among smokers who were in the precontemplation
or contemplation stages of change at baseline, but not among smokers who were
in the preparation stage at baseline. The interaction term for stage by program
participation was statistically significant (Table 2).
The program was more effective in smokers who said at baseline that
quitting smoking would be easy than it was in those who said that it would
be very difficult. Those who had made a quit attempt during the year before
enrollment were more likely to quit smoking than those who had not, but the
program doubled the odds of quitting in both groups. The program was effective
among very heavy smokers ( 35 cigarettes per day) and among teenagers (aged
15-19), but these results were statistically significant only when the 7-day
abstinence criterion was used to compare the intervention group vs the controls
(very heavy smokers, 7.9% vs 1.6%, P = .02; teenagers,
14.9% vs 3.9%, P = .02). The program was not effective
among the least educated and was most effective among the most educated. However,
in multivariate analyses with interaction terms, the effect of age and educational
level on program effectiveness was not statistically significant.
In multivariate analysis, the effectiveness of the program remained
unchanged after adjustment for baseline characteristics of participants (level
of tobacco dependence, stage of change, past quit attempts, perceived difficulty
in quitting, age, sex, and educational level). In a multivariate model, statistically
significant predictors of 4-week abstinence were participation in the program
(odds ratio [OR] = 2.8), having made a quit attempt in the previous year (OR
= 1.6), stage of change (OR = 2.0 per stage), and time to the first cigarette
in the morning, an indicator of tobacco dependence (OR = 1.1 per hour) (P<.03 for all).
ADHERENCE TO THE PROGRAM
Eighty-nine percent of respondents in the intervention group said that
they had read at least 1 counseling letter, and 65% said that they had read
at least 1 stage-matched booklet. There was an association between the number
of counseling letters read and smoking cessation (4-week abstinence of 2%
for no letter read, 6% for 1, 9% for 2, 11% for 3, and 32% for 4; 2 test for linear trend, P = .002). Among quitters
in the intervention group, 19% said that the counseling letters helped them
quit smoking "a lot," 19% "fairly," 30% "somewhat," and 32% "not at all."
COMMENT
This study showed that a computer-tailored smoking cessation program
carried out by mail increased by 2.6 the 4-week abstinence rate in daily smokers
at 7 months. The program was effective despite stringent evaluation criteria
(intention-to-treat analysis and no puff of tobacco smoke in the past 4 weeks).
The relative prevalence rate of quitting smoking observed in this study exceeded
the OR of 1.7 reported in a meta-analysis of nicotine replacement therapy
for smoking cessation.37 Our intervention also
succeeded in recruiting many smokers with low motivation to quit and in increasing
their quit rates. This is a substantial contribution because most existing
smoking cessation interventions target only the minority of smokers who are
ready to quit immediately, with few smoking cessation interventions having
been effective in precontemplators.16, 18
Our results showed that the program was effective in teenagers and heavy
smokers in terms of 1-week abstinence, although by design the size of the
trial precluded formal testing of program effectiveness in subgroups. In previous
studies, another computer-tailored intervention was ineffective in heavy smokers,38 one was effective,8
and the others did not report results for heavy smokers.15-16,18
In addition, several previous smoking cessation programs have been ineffective
in adolescents.15, 21
PUBLIC HEALTH EFFECT
This program was successfully used in a large population of smokers,
using a proactive recruitment strategy. The program tested in this trial is
now available at no charge on the Internet, in French, English, Italian, and
Danish.39 More than 40 000 smokers have
obtained an individual counseling letter by mail or on the Internet. These
smokers are regularly invited to obtain follow-up counseling, including Internet
participants if they indicate their e-mail address. The public health effect
of a smoking cessation intervention is the product of its effectiveness among
participants times its recruitment rate in the population. This is a low-intensity
intervention, leading to low abstinence rates. But given its massive recruitment
capacity, either by mail or on the Internet, this program has the potential
to have a large effect on public health. However, this study only assessed
the effectiveness of the mail version of the program, and we do not know whether
the Internet version is equally effective.
LIMITATIONS OF THE PROGRAM
The intervention was not effective among the least educated smokers,
but globally, the interaction between educational level and program effectiveness
was not statistically significant. Therefore, results in small subgroups (deciles)
should be considered with caution. The program subsumes strong reading skills
and a habit of learning from printed materials. Whether a simplified and more
readable version of the program would be effective is questionable, but this
issue deserves scrutiny. Historically, declines in smoking rates have been
stronger among the more educated.40 Developing
smoking cessation programs adapted to the least educated smokers remains a
challenge.
The program was ineffective among smokers in the preparation stage of
change. Qualitative research to understand the reasons for this finding is
under way. It is possible that the counseling paragraphs targeted at smokers
in the preparation stage of change should be improved to include more information
on relapse situations and pharmacotherapy.
Most smokers need several attempts before they quit for good. Therefore,
successive interactions are deemed indispensable for effective smoking cessation
interventions.35, 41 We observed
an association between the number of counseling letters read and smoking cessation,
which could mean that receiving more counseling letters resulted in higher
quit rates. However, participants more motivated to quit asked for more counseling
letters; therefore, a selection bias rather than a dose-response effect could
explain the increased quit rates among those who received several letters.
Finally, almost half of the participants received only 1 counseling letter.
The reluctance of respondents to fill out subsequent questionnaires raises
a concern about the feasibility of a more intensive intervention.
LIMITATIONS OF THIS STUDY
We treated all nonrespondents as smokers, but there were more nonrespondents
in the intervention group than in the control group. If proportions of nonsmokers
among nonrespondents were similar in both study arms, the program effectiveness
would be greater than that reflected in our data. Differential selection bias
could explain our findings only in the unlikely event that all nonparticipants
in the intervention group were smokers and 60% of nonparticipants in the control
group were nonsmokers.
We conducted no biochemical verification of smoking status for several
reasons. First, sustained abstinence from smoking cannot be easily biochemically
verified, given the short half-life of markers of exposure to tobacco smoke.
Second, collecting saliva or blood samples for cotinine determination or expired
carbon monoxide levels would have decreased participation rates.42
Third, biochemical verification will not change the results of most smoking
cessation studies, because self-report is generally accurate in adults and
because large between-group differences in misreporting are unlikely.43 A study conducted in a similar population44 showed that, for the association between saliva cotinine
and self-report of smoking, the area under the receiver operating characteristic
curve was 0.95, and that most cases of disagreement were because of occasional
smokers. Furthermore, at least 2 studies45-46
indicated that in intervention trials, self-report of smoking was not at all
or only minimally biased in intervention groups compared with controls; therefore,
such bias would not explain our results.
Measurement of other self-reported characteristics of participants,
including stage of change,47 level of tobacco
dependence,33 educational level, and others,
may have lacked precision, but was not biased with regard to the intervention
because assessment preceded randomization.
Because the study was not initially powered to assess the effectiveness
of the program in subgroups, all subgroup analyses should be considered with
caution. The effectiveness of computer-tailored programs in specific groups
(eg, the less educated and teenagers) requires formal testing.
Finally, this study was designed to test the effectiveness of a multicomponent
program against no intervention. Therefore, we cannot say which component
of the program was most effective (tailored letters, booklets, or successive
interactions). Experiments that separately test each of these components may
be necessary.11 For instance, to establish
whether computer tailoring contributed to the effectiveness of this program,
one would need to compare the program with a nontailored program of similar
content and intensity.
We conclude that a computer-tailored program was effective among smokers
recruited in a general population, including smokers usually resistant to
change, such as teenagers, precontemplators, and very heavy smokers. This
program can assist physicians in helping their patients who smoke,35 and it can substantially contribute to disease prevention
at a population level.
AUTHOR INFORMATION
Accepted for publication April 9, 2001.
This study was supported by grants 32-47122-96, 3233-054994.98, and
3200-055141.98 from the Swiss National Science Foundation (Dr Etter), Swiss
Cancer League, and Swiss Federal Office of Public Health, all in Bern, Switzerland,
and by the Health Authority of the Canton of Geneva. The smoking cessation
program evaluated in this article was funded by the same sponsors and by the
Geneva Cancer League; the Swiss Foundation for Health Promotion, Lausanne,
Switzerland; the Loterie Romande, Lausanne; Pharmacia & Upjohn, Dübendorf,
Switzerland; and the Health Authority of the Canton of Jura, Jura, Switzerland.
Abstract presented at the International Conference of the Society for
Research on Nicotine and Tobacco, London, England, November 26, 1999; and
at the 11th World Conference on Tobacco OR Health, Chicago, Ill, August 8,
2000.
Vincent Baujard, from the Health on the Net Foundation (http://www.hon.ch), Geneva, and Victor Gabriel, Geneva University Hospitals, developed
the smoking cessation program software.
Corresponding author and reprints: Jean-François Etter, PhD,
MPH, Institute of Social and Preventive Medicine, University of Geneva, CMU,
case postale, CH-1211 Geneva 4, Switzerland (e-mail: etter{at}cmu.unige.ch).
From the Institute of Social and Preventive Medicine, University of
Geneva (Drs Etter and Perneger), and Quality of Care Unit, Geneva University
Hospitals (Dr Perneger), Geneva, Switzerland.
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J Health Psychol 2008;13:607-623.
ABSTRACT
Randomized Trials on Consider This, a Tailored, Internet-Delivered Smoking Prevention Program for Adolescents
Buller et al.
Health Educ Behav 2008;35:260-281.
ABSTRACT
Assessing the feasibility of proactive recruitment of smokers to an intervention in general practice for smoking cessation using computer-tailored feedback reports
Gilbert et al.
Fam Pract 2007;24:395-400.
ABSTRACT
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Racial/Ethnic Disparities in Report of Physician-Provided Smoking Cessation Advice: Analysis of the 2000 National Health Interview Survey
Lopez-Quintero et al.
Am. J. Public Health 2006;96:2235-2239.
ABSTRACT
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A randomis |
