Supplementary material BMJ Open Additional file 3. The names of Ethics Committees Coding The names of Ethics Committees 1 The Ethics Committee of Daqing Longnan Hospital 2 The Ethics Committee of General Hospital of Daqing Oil Field 3 The Ethics Committee of Daqing City People's Hospital 4 The Ethics Committee of Harbin 242 Hospital 5 The Ethics Committee of The Fifth Hospital of Harbin 6 The Ethics Committee of Harbin The First Hospital 7 The Ethics Committee of Harbin First Specialist Hospital 8 The Ethics Committee of Harbin Red Cross Central Hospital 9 The Ethics Committee of The Third Affiliated Hospital of Harbin Medical University 10 The Ethics Committee of The Fourth Affiliated Hospital of Harbin Medical University 11 The Ethics Committee of The First Affiliated Hospital of Harbin Medical University 12 The Ethics Committee of Heilongjiang Land Reclamation Bureau Hongxinglong Bureau Central Hospital 13 The Ethics Committee of The Fourth Hospital of Heilongjiang Province 14 The Ethics Committee of Heilongjiang Province Land Reclamation Headquarters General Hospital 15 The Ethics Committee of Heilongjiang Red Cross Sengong General Hospital 16 The Ethics Committee of Heilongjiang Provincial Hospital of Traditional Chinese medicine 17 The Ethics Committee of The Second Affiliated Hospital of Heilongjiang University of Chinese Medicine 18 The Ethics Committee of The First Affiliated Hospital of Heilongjiang University of Chinese Medicine 19 The Ethics Committee of Jixi Mining Group General Hospital 20 The Ethics Committee of Jixi People's Hospital 21 The Ethics Committee of Jixi Hospital of Traditional Chinese Medicine 22 The Ethics Committee of The Second Affiliated Hospital of Jiamusi University 23 The Ethics Committee of Jiamusi City Tuberculosis Hospital 24 The Ethics Committee of Jiamusi Center Hospital 25 The Ethics Committee of Hongqi Hospital Affiliated to Mudanjiang Medical University 26 The Ethics Committee of Qiqihar Third Hospital 27 The Ethics Committee of the Second Affiliated Hospital of Qiqihar Medical College 28 The Ethics Committee of Qiqihar Traditional Chinese Medicine Hospital 29 The Ethics Committee of the Third Affiliated Hospital of Qiqihar Medical University 30 The Ethics Committee of Heilongjiang Provincial Hospital 31 The Ethics Committee of Shuangyashan Coal General Hospital 32 The Ethics Committee of The Shuangyashan Mining Bureau General Hospital 33 The Ethics Committee of Yichun Forestry Central Hospital Liu H, et al. BMJ Open 2019; 12:e032239. doi: 10.1136/bmjopen-2019-032239.