Hollis 1993.

Study characteristics
Methods	Design: Randomized controlled trial with 4 active trial arms Setting: 2 large primary care clinics, USA Recruitment: Recruited in practice by receptionists
Participants	2707 adults who smoked, av. age 40, 57% F, 18 cpd
Interventions	Intervention 1: participants received physician advice, carbon monoxide assessment, a quit‐smoking video, a quit kit (gum, toothpicks and cinnamon sticks), self‐help materials, mailed newsletters and a follow‐up call at 2 ‐ 4 weeks from a counselor. They were encouraged to set a quit date Intervention 2: participants received physician advice, carbon monoxide assessment, a video encouraging them to attend a smoking cessation support group, self‐help materials, coupon for quit‐smoking group, postcards reminding them of group meeting times Intervention 3: participants received the support offered to the control group and intervention 2 group combined Control: participants received a 30‐second advice message and a pamphlet
Outcomes	7d PPA at 3m and 12m Validation: Salivary cotinine
Funding Source	Public Health Service Grant 1P01‐CA44648 from the National Cancer Institute.
Author's declarations of interest	Not reported.
Notes	Strategy: Adjunctive counseling + CO monitoring Level: Patient Comparison type: Multicomponent vs. standard care
Risk of bias
Bias	Authors' judgement	Support for judgement
Sequence Generation	High risk	QUOTE: "two random digits contained in the patient's health record number were used to assign patients..."
Allocation concealment	High risk	QUOTE: "two random digits contained in the patient's health record number were used to assign patients..."
Blinding of outcome assessors All outcomes	Low risk	Smoking abstinence was biochemically validated
Incomplete outcome data All outcomes	Unclear risk	Response rates did not differ between groups. Rates not reported.