Fig. 1From: Sex differences in risk factors for depressive symptoms in patients with COPD: The 2014 and 2016 Korea National Health and Nutrition Examination SurveyFlow diagram of the study participants. FEV1, forced expiratory volume in 1Â s; FVC, forced vital capacity; KNHANES, Korea National Health and Nutritional Examination Survey; PHQ-9, Patient Health Questionnaire-9Back to article page