Results (
Thai) 2:
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Method
The data are taken from a trial reported previously (Aveyard
et al., 2003), which had ethical approval from all relevant bodies.
Between 1998 and 1999 we recruited general practices in theWest
Midlands of England. General practitioners (GPs) wrote to their
registered patients noted on the computer to be smokers. Of 29,181
written to, 2471 participated and returned a baseline questionnaire
measuring the constructs in the TTM. Participants were randomised
to one of four arms, namely control, manual, phone, and
nurse, the latter three being TTM-based.
Participants in the control arm received four widely available
products. These were Stopping Smoking Made Easier, a 24 page
10.5 14.8 cm manual on how to stop; The Quit Guide to Stopping
Smoking, a 12 page 14.8 21.0 cm booklet, which is a dispassionate
consumer review of different smoking cessation aids; and two
cards shaped like credit cards designed to be carried in a purse. One
card gave bullet points covering the benefits of smoking cessation
and the other gave bullet points concerning tips for staying quit.
Both the cards and the Quit booklet contained the smoking cessation
helpline number. Stopping Smoking Made Easier was a manual
of how to stop smoking, with chapters of advice on preparing to
stop and then stopping.
Participants in the three TTM-based intervention arms were
sent the Pro-Change programme for a healthier lifestyle, a 64 page
14.8 21.0 cm colour booklet. The booklet is produced by Pro-
Change, a company whose principals include Prochaska and
Velicer. This booklet explains how participants could stage themselves.
It has chapters for each stage with exercises to work through
that engage the appropriate processes of change. Participants in the
TTM arms received a six to eight sided letter giving feedback on all
the TTM constructs (stage, decisional balance, self-efficacy/temptation,
processes of change), which was generated from their
responses to the baseline questionnaire. The letter is individualised
by virtue of coding rules, called an expert system, which selects
stage-appropriate advice and feedback (Velicer et al., 1993).
Participants in the three TTM-based arms completed similar TTM
questionnaires at 3 and 6 months that were used to generate
further letters, including movement in stage or use of processes of
change, for example, since last assessment. Ninety five percent of
participants gave sufficient information to generate expert system
letters at baseline, 52% at 3 months, and 45% at 6 months. Evidence
suggests that one expert system letter is as effective as up to six
(Velicer, Prochaska, Fava, Laforge, & Rossi, 1999).
One of the three TTM-based interventions, namely manual,
consisted of only the interventions described above. In the phone
arm, participants were telephoned after each expert system letter
and about 70% of those getting the letter received such calls at
baseline, 3, and 6 months. Students gave the fully scripted telephone
calls designed to remind and motivate participants to use
the self-help materials and not give additional behavioural support.
The third TTM arm was nurse. Participants were asked to see their
nurse at baseline, 3, and 6 months, which was unpopular and 20%,
6% and 2%, respectively, did so. Because the nurse visits induced
participants to withdrawfrom the study, we dropped the nurse arm
part way through so that later waves of recruitment were randomised
only to control, manual, or phone. This effectively created
a four-arm and a three-arm study. There were no protocol differences
and no differences in the characteristics of participants, but
an unexpected difference in results of the four-arm trial and the
three-arm trial, which we put down to the play of chance (Aveyard
et al., 2003). We have therefore treated the data as one data set.
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