Harackiewicz 1988.
Methods | Setting: university campus health centre/medical centre, USA Recruitment: smokers applying for free cessation programme | |
Participants | 98 smokers in relevant arms, 61% female, average age 35, average cpd 27 for all participants | |
Interventions | All received advice from a doctor or nurse to quit by using the written materials, which were different for each group ∙ Self‐help manual employing intrinsic motivation approach (Stopping Smoking on Your Own with Nicorette) and nicotine gum ∙ Self‐help manual employing extrinsic motivation approach (The Doctor's Program for Stopping Smoking with Nicorette) and nicotine gum ∙ Intrinsic motivation self‐help manual only ∙ Control ‐ short booklet only, with no motivational element | |
Outcomes | Sustained abstinence at 12 months (3 months to 12 months) Validation CO < 8 ppm at each visit; saliva thiocyanate < 10 mg/dL at 3 months and 6 months; 2 participants reclassified as smokers | |
Notes | 3 vs 4 for self‐help compared to control 1 and 2 not used |
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Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Unclear risk | "Randomly assigned"; method not described |
Allocation concealment (selection bias) | Unclear risk | No details given |
Blinding (performance bias and detection bias) All outcomes | Low risk | Biochemical validation; groups differed in intervention contact but not in intensity |
Incomplete outcome data (attrition bias) All outcomes | Low risk | 22 of 197 participants did not attend any follow‐up and were excluded from analyses "drop‐out rates did not differ according to condition" Other losses assumed to be smoking |