Enhancing the validity of mortality prediction models in orthopedic surgery: two critical evaluations

aDepartment of Orthopedics, Qujing Second People's Hospital, Qujing Central Hospital of Yunnan Regional Medical Center, Qujing, China bDepartment of Gastroenterology, Qujing Second People's Hospital, Qujing Central Hospital of Yunnan Regional Medical Center, Qujing, China Xianghong Guo and Ya Yang contributions equal to this article. The data that support the findings of this study are available on request from the corresponding author, Jingling Luo, upon reasonable request. Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article. Published online ■ ■ *Corresponding AuthorAddress: Department of Orthopedics, Qujing Second People's Hospital, Qujing Central Hospital of Yunnan Regional Medical Center, Qujing, China. No. 289, Qilin West Road, Qilin District, Qujing City, Yunnan Province, China, Tel:+8615887479633. E-mail address: [email protected] (J. Luo). This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0/