Twardella 2007.

Study characteristics
Methods	Design: 4‐group cluster‐randomized controlled trial Setting: Primary care in the Rhine–Neckar region, Germany Recruitment: Providers recruited patients in practice
Participants	587 adults aged 36 – 75 years who smoked at least 10 cigarettes/day, av. age not reported, av. cpd not reported
Interventions	Intervention 1: • General medical practitioners received a 2‐hour cost‐free group tutorial in methods of promoting smoking cessation. The general medical practitioners were assured a financial remuneration of EUR 130 after study completion for each study participant they recruited who was abstinent at 12 months follow‐up Intervention 2: • General medical practitioners received a 2‐hour cost‐free group tutorial in methods of promoting smoking cessation • Participants were reimbursed up to EUR 130 for the purchase of nicotine replacement therapy or bupropion for up to 12 months. Intervention 3: • General medical practitioners received a 2‐hour cost‐free group tutorial in methods of promoting smoking cessation. General practitioners were assured a financial remuneration of EUR 130 after study completion for each study participant they recruited who was abstinent at 12 months follow‐up • Participants were reimbursed up to EUR 130 for the purchase of nicotine replacement therapy or bupropion for up to 12 months Control: usual care. No further details reported
Outcomes	6m sustained at 12m Validation: Salivary cotinine <15 ng/ml
Funding Source	Funded by the German Ministry of Education andResearch (Bundesministerium für Bildung und Forschung), project number01EB0113, within the context of the Baden–Wurttemberg Research Network on Addiction (project 01EB0113)
Author's declarations of interest	Authors declared that they had no competing interests.
Notes	Strategy: Provider training + Provider incentive + Cost‐free medication Level: Provider + Patient Comparison type: Active vs. active (isolating cost‐free medications & provider incentive) & multicomponent vs. standard care
Risk of bias
Bias	Authors' judgement	Support for judgement
Sequence Generation	Low risk	Computer‐generated random sequence used
Allocation concealment	Low risk	QUOTE: "Randomisation was performed centrally at the German Center for Research on Ageing, Heidelberg, Germany...". Computer‐generated random sequence used
Blinding of outcome assessors All outcomes	Low risk	Smoking status validated biochemically
Incomplete outcome data All outcomes	Low risk	At participant level, the overall loss to follow‐up was 15.0% (n = 88/588); 19.7% (n = 15/76) in the usual care group, 15.1% (n = 22/146) in the TI group, 15.9% (n = 23/145) in the TM group, 12.7% (n = 28/221) in the TM+TI group were lost at 12‐month follow‐up
Recruitment bias (cluster RCTs only)	Low risk	Participants were affiliated with the practice before randomization
Balanced baseline characteristics? (cluster RCTs only)	High risk	In arms TM and TI+TM, the proportion of participants in the pre‐contemplation stage was lower, and the proportion of participants in both the contemplation and preparation stages were higher than in the usual care and TI arms (P < 0.001)
Adjustment for clustering in analysis? (cluster RCTs only)	Low risk	QUOTE: "The effect of both interventions on smoking abstinence at 12 months follow‐up was assessed simultaneously in a mixed logistic regression model accounting for cluster randomisation ‐ that is, including a random effect for medical practice in the model..."