Background:
Smoking is a major risk factor for chronic obstructive pulmonary disease (COPD), and smoking cessation is the only intervention that slows disease progression. It is important to know whether current factors related to smoking and smoking cessation are different among subjects with and without COPD in order to support smoking cessation. The aim of this study was to evaluate factors related to smoking cessation and to compare characteristics and nicotine dependence among smokers with and without COPD.

Methods:
In 2005, 1614 subjects in a population-based longitudinal study of subjects with COPD and controls were examined. The Fagerström Test for Nicotine Dependence (FTND) and motivation for smoking cessation were assessed for current smokers (n = 299 total, 194 with COPD). Data on smoking cessation were collected in a follow-up in 2008 (n = 240).

Results:
Smokers with COPD had more pack-years and respiratory symptoms than smokers without COPD, whereas higher FTND scores were associated with anxiety/depression and respiratory symptoms in both groups. Nineteen percent of the smokers had quit smoking by the follow-up 3 years later, and they had significantly lower FTND scores (2.54 vs. 3.75, p < 0.001) and higher self-efficacy scores (10.0 vs. 6.0, p = 0.020) at baseline than the sustained smokers. Smoking cessation was related to low FTND scores and high self-efficacy independent of the presence of COPD, respiratory symptoms, anxiety/depression, and heart disease.

Conclusions:
The FTND score and a simple visual analog scale for assessing self-efficacy seem to be valuable instruments for predicting smoking cessation over several years, independent of COPD, respiratory symptoms, presence of anxiety/depression, and heart disease.