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Systematic review of the effectiveness of stage based interventions to promote smoking cessation

BMJ 2003; 326 doi: https://doi.org/10.1136/bmj.326.7400.1175 (Published 29 May 2003) Cite this as: BMJ 2003;326:1175

Rapid Response:

What’s Wrong with Riemsma’s Review?

The conclusions of Riemsma et al.[1] are contradicted by Spencer et
al.’s comprehensive review of 148 studies applying the Transtheoretical
Model (TTM) to smoking[2]. Of 22 studies in Spencer evaluating stage-
matched interventions, 16 were positive, 1 mixed and 5 negative. They
concluded that the literature supports stage-matched programs and that,
“Studies with positive outcomes had better designs and fewer validity
threats than those with mixed or negative outcomes” (Table 23).

Riemsma’s review included only 7 of the 22 studies in Spencer.
Riemsma et al. omitted a series of important studies with no explanation.

They seemed to give non-significant studies equal weight to
significant ones. Non-significance can easily be produced by small
samples and with TTM interventions, short follow-ups that do not permit
sufficient smokers to progress to action or maintenance, and interventions
based on a single TTM variable like stage.

In our research we usually need 400 smokers per group for .80 power,
at least 18 month follow-ups to attain predictable outcomes of 23% to 25%
abstinence and tailoring on all TTM variables to reach the predictable
abstinence range.[3 4 5] In Riemsma’s review, 16 had smaller samples
(<300/group), 11 had short follow-ups (<12 month) and 16 matched
just on stage.

In Riemsma, 3 of 4 studies with full TTM tailoring produced
significance compared to 6 of 16 matched just on stage. In Spencer, we
found 4 of 5 with full TTM tailoring were positive compared to 4 of 13
matched just on stage. The two negative fully tailored studies were with
teens. The number of fully tailored TTM studies is small, but the sample
is large (>10,000).

By chance only about 1 of 23 studies should be significant. Riemsma
counted 8 times more studies as significant than would be expected by
chance. Further, the more demanding the studies in Riemsma’s and
Spencer’s reviews (larger N, high percentage of a population
participating, longer follow-ups and fully tailored), the more likely the
results were significant. With Riemsma’s quality ratings, 1 of 5 low
quality studies (20%) produced significance (Table 3). In their middle
category, 8 of 14 (57%) produced some significance. In their top
category, 3 of 4 (75%) produced significance, with the negative study
being small, short and matched just on stage. Riemsma’s data support
Spencer’s conclusion that the higher the quality, the greater probability
of positive results.

References

1. Riemsma, RP, Pattenden, J, Bridle, C, Sowden, AJ, Mather, L, Watt,
IS, & Walker, A. Systematic review of the effectiveness of stage
based interventions to promote smoking cessation. BMJ 2003; 326: 1175-
1177.

2. Spencer L, Pagell F, Hallien, ME, & Adams, TB. Applying the
transtheoretical model to tobacco cessation and prevention: A review of
the literature. A J Health Pro 2002; 17: 7-71.

3. Prochaska, JO, DiClemente, CC, Velicer, WF, & Rossi, JS.
Standardized, individualized, interactive and personalized self-help
programs for smoking cessation. Health Psychol 1993; 12: 399-405.

4. Prochaska, JO, Velicer WF, Fava JL, Rossi JS, & Tsoh JY.
Evaluating a population-based recruitment approach and a stage-based
expert system intervention for smoking cessation. Addict Behav 2001; 26:
583-602.

5. Prochaska, JO, Velicer, WF, Fava, J, Ruggiero, L, Laforge, R,
Rossi, JS, Johnson, SS, & Lee, P. Counselor and stimulus control
enhancements of a stage matched expert system for smokers in a managed
care setting. Prev Med 2001; 32: 23-32.

Competing interests:  
I am one of the developers of TTM and I receive royalties from the University for one of the TTM programs included in the reviews. According to university, state and NIH guidelines, neither of these count as conflicts of interest.

Competing interests: No competing interests

12 June 2003
James O Prochaska
Director and Professor
University of Rhode Island - CPRC, 2 Chafee Rd, Kingston, RI 02881 USA