Please assess the completion status of the following clinical trial:

Trial Title: The Effect of High Dose N-acetylcysteine on Airtrapping and Airway Resistance in Chronic Obstructive Pulmonary Disease (COPD) Patients

Study Design Characteristics:
- Allocation: RANDOMIZED
- Intervention Model: PARALLEL
- Observational Model: None
- Primary Purpose: TREATMENT
- Time Perspective: None
- Masking: QUADRUPLE
- Phase: PHASE4
- Number of Arms: 2.0

Eligibility Criteria:
Inclusion Criteria:~* Spirometry diagnosed COPD with FEV1/FVC ratio less than 70% and FEV1 less than 80% predicted~* clinically stable and exacerbation free in the past 4 weeks~* history of at least one COPD exacerbation in the past one year~Exclusion Criteria:~* patients allergic or intolerant to NAC~* Recent use of NAC in the past one month~* history of asthma, non COPD respiratory disorders like bronchiectasis, pneumoconiosis or any active pulmonary infection~* patients on long term steroid~* patients on long term oxygen therapy or non invasive ventilation

- Gender: ALL
- Minimum Age: 40 Years
- Maximum Age: 85 Years
- Healthy Volunteers: f

Study Arms:
- Placebo (Type: PLACEBO_COMPARATOR): Placebo (600mg twice daily)
- N-acetylcysteine (Type: ACTIVE_COMPARATOR): N-acetylcysteine (600mg twice daily)

Based on this trial design, predict the completion outcome and termination type (if applicable).