Brandon 2016.

Methods	Setting: USA, population‐based Recruitment: nationwide; smokers called a toll‐free telephone number in response to advertisements in newspapers, radio, cable TV, public transit, and public service announcements
Participants	1874 smokers who want to quit, 65.8% female, average age 47.5, average cpd 20.5
Interventions	∙ Standard repeated mailings (SRM): a revised version of the Forever Free booklets, sent at baseline, and at 1, 2, 3, 5, 7, 9, and 12 months ∙ Intensive repeated mailings (IRM): same as above with 2 additional booklets (at 15 and 18 months) and 9 brief pamphlets designed to enhance the perception of social support (sent every month without a booklet) ∙ Traditional self‐help (TSH) (control): single self‐help booklet
Outcomes	Strictest: 7‐day point prevalence abstinence at 24 months Other follow‐ups: 6, 12, and 18 months Validation: none
Notes	Funding: "This work was supported by grant R01CA134347 from the National Cancer Institute. This work has also been supported in part by the Biostatistics and Survey Methods Core Facility at the H. Lee Moffitt Cancer Center and Research Institute, a National Cancer Institute‐designated Comprehensive Cancer Center (P30CA76292)" Declaration of interest: "Thomas Brandon has consulted for and received tobacco‐related research support from Pfizer, Inc. The rights to the intervention materials used in this study are owned by Moffitt Cancer Center. In the event that future revenue derives from these products, Moffitt has a revenue‐sharing plan with investigators. No other financial disclosures were reported by the authors of this paper"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Individuals were allocated to the three intervention arms using simple randomization without stratification. Intervention assignment was generated by computer upon entry of screening data into a relational database"
Allocation concealment (selection bias)	Low risk	Not described, but no face‐to‐face participant contact with researchers
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Not clear if participants were aware of other group assignments; no objective outcome measure; however, study author states there is "evidence of little benefit derived from inclusion of biochemical verification measures in low‐intensity interventions such as these that have no face‐to‐face contact, and there is little incentive to falsely report abstinence"
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dropout increases from the least to the most intensive intervention: 38% (TSH), 41% (SRM), and 43% (IRM) However, no baseline differences and similar follow‐up rates