The Prevalence of Small Airways Dysfunction In COPD Patients and The Impact on COPD Control

Chronic obstructive pulmonary disease (COPD) is a worldwide prevalent disease. During recent years, increasing attention has been directed to the importance of the contribution of small airways in respiratory diseases. The small airways (usually defined as those with an internal diameter of \<2 mm) are recognized as the major site of resistance to airflow in obstructive lung disease. Although small airway disease is known in chronic airway diseases, the importance of small airway dysfunction on disease control, exacerbations and quality of life, and the importance of taking place among treatable targets is not clear. Therefore, our aim in the study is to determine the frequency of small airway dysfunction in COPD. Our secondary aim is to evaluate the role of small airway dysfunction in disease severity, disease phenotypes, disease control, quality of life and its effect on predicting the risk of exacerbation and its role among treatable targets in chronic airway diseases.

This is a prospective cross-sectional interventional design. 100 COPD patients who applied to Mersin University Faculty of Medicine Hospital Chest Diseases Clinic between 01.10.2019-01.04.2020 will be taken. 35 healthy participants with smoking history and 35 healthy participants without smoking history who were admitted to our clinic within the same date range will be taken as control group. Impulse oscillometric pulmonary function tests will be performed to all participants. Thorax computed tomography will be performed to evaluate small airway dysfunction. To evaluate the degree of disease inflammation and phenotype in COPD patients, nitric oxide measurements will be made in the breath air with fractional exhaled nitric oxide (FENO) device. The blood eosinophil level will be studied to determine the COPD phenotype. To assess symptom control in patients with COPD, mMRC(Modified Medical Research Council) dyspnea scale will be administered. The COPD assessment test (CAT) will be applied to measure the quality of life. All patients will be followed for 1 year to record the number of exacerbations requiring emergency and hospital admissions for COPD. The effect of small airway dysfunction on the disease severity and control degree, disease phenotypes and quality of life, and the effect on the risk of exacerbation will be analyzed.

Eligibility Criteria:
Inclusion Criteria:

COPD group

* Participants who applied to the chest diseases clinic of Mersin University Hospital, between October 1, 2019 and April 1, 2020
* Participants who were diagnosed COPD with spirometry test
* Reading and signing Informed Consent Form
* Participants must be older than 18 years

Healthy control group with a history of smoking

* To apply to the chest diseases clinic of Mersin University Hospital between October 1, 2019 and April 1, 2020
* Reading and signing informed consent form
* Participants must be older than 18 years
* Must have no lung disease
* Must have 10 packs / year or more than 10 packs / year smoking history

Healthy control group without smoking history

* To apply to the chest diseases clinic of Mersin University Hospital between October 1, 2019 and April 1, 2020
* Reading and signing informed consent form
* Participants must be older than 18 years
* Must have no lung disease
* Must have no smoking history

Exclusion Criteria:

* Participants who do not sign the Informed Consent Form
* Under the age of 18 years
* Pregnant women
* Participants who with a history of cancer in the past 5 years
* Participants who previously had lung surgery
* Participants who with Interstitial Lung Disease
* Participants who with respiratory muscle disease
* Participants who with active pulmonary tuberculosis
* Participants who can not perform respiratory function tests