Cox 2022.

Study characteristics
Methods	Study design: RCT Country: USA Recruitment method: through media and physician referral Double‐blind parallel‐group RCT
Participants	500 adult African Americans who smoked 5+ CPD, motivated to quit. Baseline average CPD: 12.5. Average age 52. 87% female
Interventions	Varenicline (standard dose) vs placebo All participants received culturally relevant individualised counselling over 16 weeks
Outcomes	7‐day PPA at 6 months biochemically validated by saliva cotinine 15 ng/mL
Notes	Study funding: “This work was funded by the National Institute on Drug Abuse (R01DA035796; Cox). Pfizer Global Pharmaceuticals and Pfizer Global Medical Grants provided study medication. Analytical chemistry was supported in part by P30 DA 012393 from the National Institute on Drug Abuse and S10 RR 026437 from the National Center for Research Resources (Benowitz). Dr Tyndale is supported by the Canada Research Chairs Program (Canada Research Chair in Pharmacogenomics). Dr Ahluwalia is supported by P20GM130414, a National Institutes of Health– funded Centers of Biomedical Research Excellence. […] The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.” Author declaration of interests: “Dr Nollen reported receiving grants from the National Institutes of Health during the conduct of the study and nonfinancial support from Pfizer, which has provided study medication for this and other studies, outside the submitted work. Dr Mayo reported receiving grants from the National Institutes of Health during the conduct of the study. Dr Faseru reported receiving grants from the National Institutes of Health during the conduct of the study. Dr Ellerbeck reported receiving grants from the National Institute on Drug Abuse during the conduct of the study. Dr Tyndale reported consulting for Quinn Emanuel Urquhart & Sullivan and Ethimos and receiving grant support from the National Institutes of Health and Canadian Institutes of Health Research during the conduct of the study for work on other projects. Dr Benowitz reported receiving personal fees from Pfizer for serving on an advisory committee and Achieve Life Sciences for serving on a data and safety monitoring board and being a paid expert witness in litigation against tobacco companies outside the submitted work. Dr Ahluwalia reported receiving personal fees from Respira Technologies as a consultant and equity owner outside the submitted work. No other disclosures were reported”
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"participants were assigned to receive varenicline or placebo in a 3:2 ratio via computergenerated individual random assignment to allow more participants to receive active treatment and concurrently strengthen evaluation of medication adverse events (Figure 1). Randomization was stratified by smoking level (≤10 or >10 cigarettes/d) and sex. A block size of 10 was used to generate the randomization schema."
Allocation concealment (selection bias)	Low risk	"The university pharmacy bottled study medication, per randomization code, labelled with participant ID numbers to ensure that study staff, investigators, and participants were blinded to treatment assignment."
Blinding (performance bias and detection bias) All outcomes	Low risk	Abstinence was biochemically validated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rates similar between study arms
Selective reporting (reporting bias)	Low risk	Outcomes pre‐specified in NCT record are reported in results paper