OBJECTIVES: This study aims to examine the benefit of quitting smoking among chronic obstructive pulmonary disease (COPD) patients using medical and pharmacy claims database and medical check-up database of a nationally representative sample cohort in South Korea.

METHODS: Patients who are older than 40, newly diagnosed as COPD, and received COPD medication two times for a year, were identified from 2004 database. Those who had been previously diagnosed as COPD for two years before the index diagnosis were excluded. The severity of COPD was defined as three groups based on medication use and tertiary institute visits; low, middle and high grade. Subjects were followed up to 12 years until December 2016. The group who quitted smoking was compared with never-smokers and those who continuously smoked. Outcomes were mortality rate, major adverse cardiovascular events (MACE), health care expenditure, prevalence of high grade COPD and exacerbation rate. Covariates were age, gender, income level, body mass index, the severity of COPD at the base, lifetime amount of smoking, and the number of chronic diseases. Differences between groups were assessed using Cox proportional hazard regression analyses.

RESULTS: We identified 165,986 patients with moderate-to-severe COPD. Among those who had valid medical check-up information in the database (24,760, 14.9%), we found 6,760 continuous smokers (4.1%), 2,498 quitters (1.5%), and 15,502 never-smokers (9.3%). Mortality rate of successful quitters was lower than continuous smokers and higher than never-smokers (25.7% vs.27.2% and 21.4%). Stratified by age groups, the difference between quitters and continuous smokers was greater among the group of 40's and 50's, compared to other age groups. After controlling for covariates, there was no significant difference among three groups in mortality rates at the level of p<0.1.

CONCLUSIONS: Regards as mortality rates, we found no evidence from the nationally representative sample cohort on the benefit of smoking cessation among new COPD patients.