1. Department of Thoracic Surgery, The Second Affiliated Hospital of Lanzhou University, Lanzhou, Gansu 730030, P.R. China
2. The Evidence Based Medicine Center of Lanzhou University, Lanzhou, Gansu 730000, P.R. China
3. Department of Neurosurgery, The Second Affiliated Hospital of Lanzhou University, Lanzhou, Gansu 730030, P.R. China
4. Department of Thoracic Surgery, Shenzhen Hospital of Southern Medical University, Shenzhen, Guangdong 518100, P.R. China