To evaluate the effect of Mucomyst nebulizer therapy on improvement in symptoms and quality of life in COPD patients with difficulty of expectoration.

In this non-interventional observational study, treatment for individual subjects is determined by the investigator according to the status of individual subjects in routine clinical practice. In this circumstance, doses for each drug product will not be specified in the protocol but will be determined as appropriate by the investigator with the product label and the subject's medical condition taken into consideration.

Primary objective To evaluate the effect of Mucomyst on improvement in difficulty of expectoration symptoms in COPD patients with difficulty of expectoration.

Secondary objective To evaluate the effect of Mucomyst on improvement in quality of life and safety in COPD patients with difficulty of expectoration.

Inclusion Criteria:

1. man and woman at the age of ≥40 years old
2. Diagnosed with COPD within the past 1 year based on pulmonary function test (post bronchodilator FEV1/FVC<0.7)
3. COPD Assessment Test (CAT) phlegm score ≥2
4. Smoking history ≥10 pack-years* (*Pack-year: number of packs of cigarettes smoked per day X number of years the individual has smoked)
5. Patient who is to be treated with Mucomyst nebulizer therapy to alleviate difficulty of expectoration symptoms
6. Voluntary written informed consent to study participation and to use of personal information for this study

Exclusion criteria

1. History of hypersensitivity reactions to any of the components of NAC or contraindicated to NAC therapy according to the product label
2. Treated with Mucomyst within the past 4 weeks
3. Newly treated with 'drugs for the alleviation of expectoration symptoms (antitussives/expectorants)' or dose changed for ongoing therapy within the past 4 weeks
4. Pregnant and lactating woman
5. Participating in another trial with investigational product treatment at the time of enrollment to the present study
6. Ineligible for study participation in the opinion of the investigator

Chronic Obstructive Pulmonary Disease (COPD) patients with Difficulty of Expectoration. Total 100 subjects