1 Department of General Practice/Department of Geriatrics, Xi'an No. 3 Hospital, The Affiliated Hospital of Northwest University, Xi'an, Shaanxi, China.
2 Town Health Center, Weiyuan County Shangwan Town Health Center, Dingxi, Gansu, China.
3 Department of Thoracic Surgery/Department of Lung Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China.