Burns 2016.

Study characteristics
Methods	Study design: parallel RCT Country: USA Recruitment: by the Colorado quit‐line ‐ participants were recruited during regular initial quit‐line calls
Participants	1495 smokers: smoking 16 to 20 cigarettes per day, agreed to receive free NRT, absence of a condition requiring physician approval for NRT 40.0% men; average cigarettes per day 19.8; most smoked within 5 minutes of waking and had been smoking for > 10 years
Interventions	1) 4 weeks of free NRT (patches). However, participants were encouraged to complete 10 weeks of NRT, sourcing the remainder themselves. 2) 8 weeks of free NRT (patches), shipped in 2 x 4‐week batches. Participants were required to request the second batch. Participants were encouraged to complete 10 weeks of NRT, sourcing the remainder themselves.
Outcomes	Self‐reported prolonged abstinence at 6‐month post‐quit day; no biochemical validation Other abstinence measures: self‐reported 7‐day and 30‐day PPA at 6 months Adverse events: not measured
Notes	Only two‐thirds of group 2 (8 weeks of free NRT) accepted second 4‐week batch of NRT. Median time NRT used same in both groups (35 days) The study was funded by a Pfizer Scholar Grant in public health and the Colorado Department of Public Health and Environment contract number FLA‐11‐16830 Conflicts of interest: none
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Enrolled study participants were randomised"; but no detail given on how randomisation took place
Allocation concealment (selection bias)	Unclear risk	As above. No detail on allocation concealment in text
Blinding (performance bias and detection bias) All outcomes	High risk	Quote: "Coaches ask all quitline enrolees during second and subsequent coaching calls about their NRT utilisation, and those who are eligible for a second shipment are asked whether they need it." No blinding. Although it would have been impossible to blind participants, it would have been possible to blind outcome assessors, and we therefore deem this study to be at high risk of detection bias
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dropout rates at 6 month were 311/738 in group 1 (4 weeks of free NRT) and 321/757 (8 weeks of free NRT). There was less than 50% dropout overall and rates were similar between groups.