2.2 Collection of data
Data on the age, gender, body mass index (BMI), smoking status, and fall history in the last 1 year were recorded for all subjects. The respiratory function tests were performed with reference to the American Thoracic Society/European Respiratory Society criteria, and the parameters forced vital capacity (FVC), forced expiratory volume first second (FEV1), and the ratio of FEV1/FVC were recorded.8 In addition, the scores of 6-min-walk-test (6MWT), modified Medical Research Council (mMRC) dyspnea scale, COPD assessment questionnaire (CAT), BMI (B), the severity of airway obstruction (O), the dyspnea severity (D), and exercise capacity (E) (BODE) index were also collected. All patients with COPD were classified into 4 groups based on the GOLD 2017 criteria. Accordingly, the patients with high frequency of symptoms were assigned to Group B or D, while those with high risk of exacerbation were assigned to Group C or D.9 All subjects were informed about the balance tests, and based on how the tests were performed, BBS, SLS, 5STS, FSST, and TUG tests were performed in the physical therapy and rehabilitation outpatient clinic.