1. West China Hospital,Sichuan University; Chinese Cochrane Centre; No. 37 Guo Xue Xiang Sichuan University Chengdu Sichuan China 610041
2. West China Hospital; Division of Cardiology, Internal Medicine; Sichuan University Chengdu Sichuan China 610041
3. West China Hospital, Sichuan University; Chinese Cochrane Centre, Chinese EBM Centre; No. 37, Guo Xue Xiang Chengdu Sichuan China 610041
4. Institute of Social and Preventive Medicine; Department of Social Medicine; Finkenhubelweg 11 Bern Switzerland 3012