Etter 2004.
Methods | Setting: community, Switzerland Recruitment: mailing to population registers (not selected) | |
Participants | 2934 smokers aged 15+, 74% pre‐contemplators, 40% tried to quit in previous year, 51% female, average age 36, average cpd 20 | |
Interventions | ∙ Tailored 8‐page letter plus SoC‐matched booklets; at 2 months, 4 months, 12 months ‐ repeat questionnaire to initiate further letter ∙ No intervention | |
Outcomes | Abstinence at 24 months (in maintenance stage; quit for > 6 months), 4 weeks; 7‐day abstinence also reported Validation: none | |
Notes | Tailored self‐help vs nothing; approximately half of group 1 received 1 letter only
Effects at 6 months (Etter Arch Int Med 2001) not sustained at 24 months Relative difference smaller if shorter‐term abstinence used |
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Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Low risk | Randomisation: "list of random numbers" |
Allocation concealment (selection bias) | Unclear risk | No details given |
Blinding (performance bias and detection bias) All outcomes | High risk | "...members of the control group received a letter indicating that they had been attributed to that group..." No validation; intervention intensity higher than for control group |
Incomplete outcome data (attrition bias) All outcomes | Low risk | Loss to follow‐up 14.0% in 1; 10.7% in 2 All non‐responders included in ITT analysis |