Parkes 2008.
| Methods | Setting: primary care (5 general practices, UK) Recruitment: by letter to registered patients Selection: not selected by motivation | |
| Participants | 561 current smokers (not defined) aged > 35, 54% female, average age 53, mean cpd: 17, 29% pre‐contemplative, 32% contemplative, 17% preparation, 21% action Therapists: study staff member | |
| Interventions | All participants had lung function assessed by spirometry before randomisation. Strongly encouraged to give up and given written contact details of National Health Service (NHS) smoking cessation services. If evidence of asthma or restrictive lung disease, advised to see GP. Told they would be re‐tested at 12 months. Intervention 1: immediate verbal feedback of lung age with explanation. Described as normal if lung age less than or equal to chronological age. Intervention 2: letter giving test results without lung age | |
| Outcomes | Definition of abstinence: unspecified Duration of follow‐up: 12 months Biochemical validation of non‐smokers: exhaled CO, cotinine < 14.2 ng/mL | |
| Identification | ||
| Notes |
Source of funding: Leading Practice Through Research award from the Health Foundation Declaration of interest: None declared. |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | "A clerk (who then took no further part in the study) prepared 600 sequentially numbered opaque sealed envelopes, each containing a card with allocation group determined by computer generated random number (odd = intervention)” |
| Allocation concealment (selection bias) | Low risk | “If the participant met the inclusion criteria and gave consent, he or she was entered into the study and underwent baseline spirometry. The next numbered envelope in the series was then opened to determine allocation group” |
| Blinding of outcome assessment (detection bias) All outcomes | Low risk | Follow‐up assessors blind to allocation group, biochemical validation used. |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | 11% lost to follow‐up in each arm, included as smokers. |