2.1 Study design and patients
In this study, a total of 71 patients with COPD admitted to the Adnan Menderes University outpatient clinics of chest diseases during March 2018–2019 and diagnosed with COPD with reference to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines7 were included in the study. The control group contained 70 individuals aged ≥40 years with normal respiratory function test results. Subjects with communication problems, postural orthostatic hypertension, unstable cardiac disease, hearing or visual impairments, any skeletal or neurological problems that may cause falls, as well as those on sedatives (such as antidepressants), those operated from the lower limbs, those with balance and gait impairments, and those using assistive walking devices were excluded from the study. The study was approved by the Adnan Menderes University Non-invasive Clinical Studies Ethics Committee (No: 2018/1297), and the study was conducted in accordance with the principles of the Declaration of Helsinki. All participants provided their informed signed consent forms.