Association of early-stage COVID-19 policy changes with smoking cessation outcomes: secondary analysis of two randomised trials in Hong Kong

AIM: To examine whether smoking cessation outcomes among Chinese-speaking adults who smoked and used community-based smoking cessation services in Hong Kong differed before and after early-stage COVID-19 policy changes. DESIGN: Secondary analysis of two randomised controlled trials, comprising one individually randomised trial and one cluster randomised trial, conducted in Hong Kong between 2018 and 2021. SETTING: Participants who used a community-based smoking cessation service were recruited. PARTICIPANTS: 1762 Chinese-speaking adults who smoke or recently quit smoking (80.5% male). MEASURES: The primary outcome was the 6-month biochemically validated abstinence rate before and after the first major policy change on 25 January 2020, when the COVID-19 emergency response level was raised. Secondary outcomes were self-reported 7-day point prevalence abstinence at 3-month and 6-month follow-ups. Sensitivity analyses were conducted for subsequent policy changes on 8 February and 28 March 2020. Modified Poisson regression models with cluster-robust SEs, adjusted for group allocation, trial, age, gender, baseline smoking intensity and intervention type, were used. FINDINGS: After the 25 January 2020 policy cut-off, the 6-month biochemically validated abstinence rate significantly decreased from 12.3% before the cut-off to 6.8% (risk ratio (RR) (95% CI) 0.55 (0.40 to 0.76), p<0.001) after the cut-off. Self-reported 7-day abstinence rates were also lower after the policy change at the 3-month (49.1% vs 31.3%, 0.60 (0.51 to 0.71), p<0.001) and 6-month (41.0% vs 32.2%, 0.78 (0.69 to 0.88), p<0.001) follow-ups. Sensitivity analyses using the 8 February and 28 March cut-off points showed generally consistent reductions in abstinence outcomes. CONCLUSION: Early-stage COVID-19 policy changes in Hong Kong were associated with significantly lower tobacco abstinence rates among adults using or being referred to community-based smoking cessation services. Rapidly adaptable cessation support, including telehealth counselling and continuity of pharmacotherapy, is needed to sustain quit attempts during public health emergencies.