Maheu 1989.

Methods	Country: USA Setting: 2 aerospace worksites (Competition: ˜4500 employees; No Competition: ˜12000 employees) in San Diego, California. Both sites had recent smoking bans in public areas. Design: non‐randomized comparative study, cluster design
Participants	Total 56 (Competition: 32, No Competition: 24). Significant differences on age and years smoking. Av 29.9 cpd, 41% female, 12% blue‐collar workers. Recruitment at Competition site was 2% of eligible smokers, versus 0.6% at No Competition site (P < 0.01).
Interventions	Both sites received 9 x 2‐hour class meetings (self‐monitoring, aversive ‘smoke‐holding', nicotine gum) and 9 x 1‐hour maintenance meetings over 14 weeks. Strategies included stress and weight management, relaxation and RP. Participants all paid a US$50 tuition fee, of which they could win US$35 back for attendance and abstinence. A buddy system was promoted where pairs or triads of participants could contact each other for 3 months after the quit day. 1. Competition participants were divided into 3 teams; team with most abstainers at 3 months won pooled prize of US$160. Also a site‐wide raffle, and a participants' raffle for attendance at meetings. Non‐participants could sponsor a smoker who they could contact as desired. Non‐participants whose sponsored smokers were confirmed abstinent at 3 months were given 5 tickets for a US$150 travel voucher raffle. 2. No Competition participants abstinent at 3 months received pooled prize (US$120) divided equally.
Outcomes	Continuous abstinence CO < 10 ppm from weeks 5, and at 3 months and 1 year. SCN also collected at 3 months in ‘bogus pipeline' procedure. ‘Buddy' supportiveness. Number of sick days.
Notes	Allocation was by worksite, but analysis by individual participant. Intervention being tested and rewarded was group co‐operation and competition. All participants received partial refunds for programme attendance, and for attending 1‐year follow‐up. Study was funded by Merrell Dow Pharmaceuticals (Nicorette products). Originally in C&I.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Not randomized.
Allocation concealment (selection bias)	High risk	See above
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Biochemical validation used.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All participants were followed up.