BACKGROUND AND AIMS: Evidence for motivational interviewing for smoking cessation is weak, with limited data on long-term abstinence rates. This trial aimed to evaluate the effect of in-hospital motivational interviewing-based smoking cessation counselling combined with proactive referral to community-based follow-up on 6- and 12-month continuous smoking abstinence in patients with atherosclerotic vascular disease.

DESIGN: Multicentre, randomised, open-label, blinded-end-point trial with 1:1 randomisation.

SETTING:Three secondary care hospitals in Norway, with recruitment from November 2021 to October 2023.

PARTICIPANTS: Hospitalised patients with established atherosclerotic vascular disease who smoked ≥1 cigarette daily prior to unplanned or elective hospitalisation. A total of 221 were randomised (40% women, mean age 65.2 years), of whom 213 were included in the primary analysis due to 7 deaths and 1 withdrawal.

INTERVENTION AND COMPARATOR: In the intervention group (n = 109), a trained nurse conducted a single 30-minute motivational interviewing-based counselling session, provided a leaflet explaining the local community-based cessation programme, sent discharge information to the general practitioner and arranged for a personal telephone invitation from the centre staff to the follow-up programme. In the control group (n = 111), a physician gave brief cessation advice and the nurse provided a leaflet about the cessation programme and sent discharge information to the general practitioner.

MEASUREMENTS: The primary outcome was self-reported continuous smoking abstinence at 6 months. Secondary outcomes included biochemically validated abstinence (measurement of exhaled carbon monoxide) at 6 months and self-reported abstinence at 12 months. Exploratory outcomes included recurrent vascular events over a median 18-month follow-up.

FINDINGS: Smoking abstinence at 6 months was 49.5% (53/107) and 24.5% (26/106) in the intervention and control groups, respectively [odds ratio (OR) = 3.08, 95% confidence interval (CI) = 1.70-5.55, P < 0.001]. The number needed to treat to achieve one additional abstinence was 4 (95% CI = 3-9). Biochemically validated abstinence was 44.9% (48/107) and 20.8% (22/106) in the intervention and control groups, respectively (OR = 3.28, 95% CI = 1.76-6.12). At 12 months, smoking abstinence was 45.7% (48/105) and 27.5% (28/102) in the intervention and control groups, respectively (OR = 2.31, 95% CI = 1.27-4.20). After a median of 18-month follow-up, a prespecified vascular event occurred in 24.8% (27/109) and 34.2% (38/111) of intervention and control participants, respectively.

CONCLUSIONS: In-hospital motivational counselling combined with proactive referral to follow-up in a community-based cessation programme approximately doubled long-term smoking abstinence rates in patients with atherosclerotic vascular disease and reduced occurrence of a new vascular event.