Association between body mass index and pulmonary function of patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease （COPD） is a major cause of chronic morbidity and mortality throughout the world. It is a preventable and treatable disease with significant extra pulmonary effects that may contribute to the severity in individual patients. It is characterized by airflow limitation that is not fully reversible. The diagnosis of COPD should be confirmed by spirometry. Body mass index （BMI） is an important indicator that can well reflect nutritional status of patients, and low BMI is an independent risk factor for mortality in patients with COPD.