Effectiveness of a Brief Self-determination Theory–Based Smoking Cessation Intervention for Smokers at Emergency Departments in Hong Kong

IMPORTANCE Clinicians have an opportunity to provide smoking cessation interventions to smokers who present to emergency departments (EDs). The effectiveness of a brief intervention based on self-determination theory for smoking cessation is uncertain. Objective To examine the effectiveness of a brief intervention based on self-determination theory for smoking cessation (immediate or progressive) among Chinese smokers presenting at EDs in Hong Kong. Design, Setting, and Participants This single-blind, multicenter intent-to-treat randomized clinical trial was conducted at the EDs of 4 major acute care hospitals in different districts of Hong Kong. In total, 1571 smokers 18 years or older who presented at 4 major EDs between July 4, 2015, and March 17, 2017, were randomized into an intervention group (n = 787) and a control group (n = 784). Interventions The intervention group received brief advice (about 1 minute) and could choose their own quit schedules (immediate or progressive). The control group received a smoking cessation leaflet. Main Outcomes and Measures Follow-up visits were conducted at 1, 3, 6, and 12 months. The primary outcome measure, by intent to treat, was biochemically validated abstinence at 6 months. Results Participants (N = 1571) included 1381 men (87.9%); the mean (SD) age at baseline was 47.4 (16.4) years. Among participants who self-reported abstinence at 6 months, 50.3% (85 of 169) had biochemical validation by both an exhaled carbon monoxide test and a saliva cotinine test. Compared with the control group, the intervention group had statistically higher biochemically validated abstinence at 6 months: 6.7% (53 of 787) vs 2.8% (22 of 784) (P < .001), with an adjusted relative risk of 3.21 (95% CI, 1.74-5.93; P < .001). The intervention group also had higher self-reported quit rates at 6 months (12.2% [96 of 787] vs 9.3% [73 of 784], P = .04) and 12 months (13.0% [102 of 787] vs 8.5% [67 of 784], P < .01), as well as higher biochemically validated abstinence at 12 months (7.0% [55 of 787] vs 3.7% [29 of 784], P < .001). The additional cost for each intervention group participant was US $0.47, with an estimated gain of 0.0238 quality-adjusted life-year. The incremental cost per quality-adjusted life-year (US $19.53) fell within acceptable thresholds. Conclusions and Relevance This brief, low-cost self-determination theory-based intervention for smokers presenting at EDs effectively increased the biochemically validated quit rate at 6 months. If delivered routinely, such a simple intervention may offer a cost-effective and sustainable approach to help many smokers quit smoking.