This study is designed as a multicenter, prospective and retrospective and descriptive epidemiology study.

This study is planned to evaluate 2 years of exacerbation in COPD patients and to investigate correlation of COPD disease progress and its exacerbation.

This study is designed with 6 months of subject enrollments, 12 months of retrospective study, and 12 months of prospective study. Hence, each patient will be participating in the study for 12 months, while the actual data collections from the patients will take a total of 24 months.

The statistical analysis of this study will be done twice, at the completion of 1 year retrospective data collection and at the completion of next 1 year follow-up.

The 1st statistical analysis of retrospective study includes exacerbation rate, duration of hospitalization for exacerbation and lung function test for the past 1 year from the enrollment and comorbidities, COPD assessment (CAT) and COPD medication at the enrollment will be analyzed.

The 2nd statistical analysis of prospective 1-year follow-up includes changes in exacerbation rates, comparison of lung function test results, comorbidities, COPD assessments (CAT) and COPD medications of retrospective and prospective studies for the 2 years as well as mortality rate.

Inclusion Criteria:

1. Over 40 years old
2. Patient with at least 1 year of medical history of COPD as defined by GOLD criteria
3. Patient with having past 1 year medical record at the investigational site
4. Patient who signed Informed Consent Form

Exclusion Criteria:

1. Patients who are currently involved in any other interventional studies or possible to be involved for the next 1 year
2. Patients currently diagnosed with cancer

Patients with COPD