Schumann 2008.
Methods | Setting: community, Germany Recruitment: from participants in a general population health examination survey | |
Participants | 847 smokers (ex‐smokers in study not included here); 46% female (full sample), average age 44 years (full), average cpd 15 Controls more likely to be in preparation (32% vs 20%) and to have past year quit attempt |
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Interventions | ∙ Assessment only (completed questionnaires on 3 occasions) ∙ Expert system ‐ tailored 3 to 4‐page letter and 8 to 26‐page SoC‐matched booklet at 0 months, 3 months, and 6 months | |
Outcomes | Abstinence at 24 months; sustained 18 months' follow‐up (other measures of abstinence also reported) Validation: none | |
Notes | Tailoring ‐ 67% got 3 letters, 21% 2, 13% only 1 72% reported reading some materials |
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Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Low risk | Each participant was assigned a unique computer‐generated random number between 0 and 1; the data file was sorted by ascending random numbers; participants were then consecutively assigned to the 3 study conditions |
Allocation concealment (selection bias) | Low risk | No opportunity to alter allocation or exclude |
Blinding (performance bias and detection bias) All outcomes | Low risk | Although no biochemical validation, written contact only; participants in control group do not appear to have known of intervention; all participants engaged in long‐term questionnaires re smoking status, so differential misreport judged unlikely |
Incomplete outcome data (attrition bias) All outcomes | Low risk | Somewhat greater loss in intervention (34%) than in control (27%) Meta‐analysis includes those lost as smokers Study authors report that generalized estimation equation gave similar results |