The goal of this observational study is to investigate the accuracy of Accuhaler tester, Ellipta tester and Turbutester in patients with chronic obstructive pulmonary disease (COPD). The main question it aims to answer is:

• Do Accuhaler tester, Ellipta tester, and Turbutester demonstrate comparable accuracy to the In-check DIAL for assessing inspiratory inhalation force in COPD patients?

This study is a cross-sectional study. COPD patients aged 40 years or older will be included. Peak inspiratory flow rate (PIFR) will be assessed using In-check DIAL as the standard tool. PIFR will be tested in each patient using Accuhaler tester, Ellipta tester and Turbutester.

Inclusion Criteria:

• COPD diagnosis with confirmed by post-bronchodilator forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) <0.7
• Age 40 years or older
• Smoking history 10 pack-years or more

Exclusion Criteria:

• COPD exacerbation within 3 months
• Oral or intravenous corticosteroid treatment within 6 weeks
• Inability to perform assessment of peak inspiratory flow rate
• Asthma
• Tracheostomy, invasive or noninvasive mechanical ventilation

COPD patients aged 40 years or older who are confirmed diagnosis by spirometry (post-bronchodilator FEV1/FVC <0.7) and smoking history 10 pack-years or more.

IPD and documents will be available for sharing immediately after publication for a period of 2 years.