: High-intensity smoking cessation programs generally lead to more continuous abstinence, however, lower rates of success have been reported among heavy smokers. The aim was to evaluate continuous abstinence among heavy smokers during the intensive 6-week Gold Standard Program (GSP) and to identify modifiable factors associated with continuous abstinence. Methods
: In this nationwide clinical study based on 36,550 smokers attending an intensive cessation program in Denmark. Heavy smoking was defined as ≥7 points in the Fagerström Nicotine Dependency Test, smoking ≥20 cigarettes daily or ≥20 pack-years. Results
: Overall, 28% had a Fagerström score ≥7 points, 58% smoked ≥20 cigarettes daily and 68% smoked ≥20 pack-years. Continuous abstinence was 33% in responders (6-months response rate: 78%); however, abstinence was approximately 1–6% lower in the heavy smokers than the overall population. Attending GSP with an individual format (vs.
group/other, OR 1.23–1.44); in a hospital setting (vs.
pharmacy/municipality services, OR 1.05–1.11); and being compliant (attending the planned meetings OR 4.36–4.89) were associated with abstinence. Abstinence decreased in a dose-dependent manner with increasing smoking severity. Conclusions
: Abstinence after GSP was 1–6% lower in the heavy smokers than in the overall study population. Modifiable factors may be used for small improvements in continued abstinence. However attempts to improve compliance seemed especially promising.