Gonzales 2014.
| Study characteristics | ||
| Methods | Country: 37 centres in 8 countries: USA (8), Australia (4), Belgium (4), Canada (4), Czech Republic (4), France (3), Germany (5), UK (5)
Setting: clinics, hospitals, academic research centres Aim: to evaluate the efficacy and safety of retreatment with varenicline in smokers who had taken varenicline for ≥ 2 weeks in a previous SC attempt Study design: double‐blind placebo‐controlled multinational RCT Dates conducted: December 2010‐November 2012 |
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| Participants | 498 adult smokers (varenicline 251, placebo 247) with previous use of 2+ weeks of varenicline at least 3 months prior to screening, aged 18+, CPD 10+, motivated to quit. Mean age 47.5, 50.4% women, 93% white, mean CPD 20.5, mean FTND 5.5 | |
| Interventions |
Brief (< 10 min) counselling at each contact. TQD set for week 1 visit. Clinic visits at weeks 1, 2, 3, 4, 6, 8, 9, 10, 11, 12; 13, 16, 24, 32, 40, 48, 52. Brief phone calls at weeks 5, 7, 14, 20, 36, 44. Dosage could be halved if intolerable |
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| Outcomes | Primary: CAR at weeks 9‐12, 9‐52 Secondary: CAR at weeks 9‐24; 7‐day PPA at weeks 12, 24, 52 Validation: CO < 10 ppm |
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| Notes | New for 2016 update Funding: Pfizer Author declaration of interests: "D.G. reports grants, and nonfinancial and other support from Pfizer during the conduct of the study; and grants, stock ownership, and nonfinancial and other support from Pfizer, grants from Nabi Biopharmaceuticals, and personal fees and nonfinancial support from GlaxoSmithKline outside the submitted work. P.H. reports grants from Queen Mary University of London during the conduct of the study and grants and personal fees from Pfizer, McNeil, GlaxoSmithKline, and Novartis outside the submitted work. L.P. reports grants from Pfizer outside the submitted work. K.N. reports funding and nonfinancial support from Pfizer during the conduct of the study and personal fees from Pfizer (Belgium) outside the submitted work, for serving as an advisory board member and for lectures. L.‐J.T, T.D.M., and J.T. are employees of Pfizer." |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | "Eligible participants were randomly assigned to receive either varenicline or placebo at a 1:1 ratio for 12 weeks of drug treatment using computer‐generated block randomization within each site" |
| Allocation concealment (selection bias) | Unclear risk | Not stated |
| Blinding (performance bias and detection bias) All outcomes | Unclear risk | Not stated |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Losses to follow‐up fully reported. ITT analyses conducted |
| Selective reporting (reporting bias) | Low risk | Prespecified outcomes from trial registry reported in results paper |