Cabezas 2011.

Study characteristics
Methods	Design: Cluster‐randomized controlled trial Setting: Primary care practices, Spain Recruitment: Patients who attended primary care practice for any reason and who answered ‘yes’ to the question: ‘Do you currently smoke cigarettes?’.
Participants	176 basic care units within 82 primary care centers 2827 people who currently smoked, aged 14 – 85 years. Randomized to intervention (1482) or control (1345). 50% F, average age 43, 20 cpd
Interventions	Common components in both groups: brief advice for patients and training (of different breadth of content for each group) for healthcare professionals Intervention: • Healthcare professionals received a 20‐hour workshop on smoking cessation interventions • Participants received intervention tailored to TTM stage: ‐ Precontemplation or contemplation stage: brief motivational interview and leaflet ‐ Preparation or action who preferred no specific help: brief advice, leaflet, an offer of NRT and 1 follow‐up contact ‐ Preparation or action stage requesting specific help: 9 scheduled follow‐up visits over 6 months that included behavioral interventions and pharmacological agents Control: • Healthcare professionals only received the training session in the practical aspects of the protocol • Participants received usual care that included brief smoking cessation advice for diseases related to tobacco consumption
Outcomes	12m continuous abstinence at 24m follow‐up Validation: Expired CO < 10 ppm
Funding Source	Spanish Preventive Services Network (Red de Actividades Preventivas y Promoción de la Salud en Atención Primaria) granted by the Carlos III Health Institute (Instituto de Salud Carlos III) (G03/170 y RD06/0018) and from another project grant (PI021471) in 2002 also from the Carlos III Health Institute
Author's declarations of interest	Authors declared that they had no conflict of interest.
Notes	Strategy: Provider training + adjunctive counseling Level: Patient + Provider Comparison type: Multicomponent vs. standard care
Risk of bias
Bias	Authors' judgement	Support for judgement
Sequence Generation	Low risk	QUOTE: "the random sequence was generated by an independent statistician who used a computer program and who was blinded to the basic care unit identities"
Allocation concealment	Low risk	QUOTE: "Basic care unit were informed about their allocation after giving final consent to participation"
Blinding of outcome assessors All outcomes	Low risk	Smoking status was validated by carbon monoxide levels
Incomplete outcome data All outcomes	Low risk	Attrition rates were under 50% and similar between groups. The overall loss to follow‐up was 44.0% (n = 1244/2827); 43.3% (n = 641/1482) in the intervention group and 44.8% (n = 603/1345) in the control group were lost to follow‐up at 2 years
Recruitment bias (cluster RCTs only)	Low risk	Participants were affiliated with the practice before randomization. QUOTE: "...recruited from 2003 to 2005 who consulted a primary care centre for any reason and who answered 'yes' to the question: 'do you currently smoke cigarettes?"
Balanced baseline characteristics? (cluster RCTs only)	Low risk	Statistically significant differences between the study groups were found in the following variables: stage of change (precontemplation, contemplation, preparation, action), Richmond test, confidence in quitting and readiness to quit (P = 0.001); however, these differences were small and clinically irrelevant
Adjustment for clustering in analysis? (cluster RCTs only)	Low risk	QUOTE: "...a multi‐level analysis was conducted initially. Because no significant variation was found between basic care units, a logistic regression analysis of individual level data using methods for clustered data (adjusting the standard errors for the design effect) was used in order to analyse the intervention as a predictor of smoking cessation"