Association between the risk of death and serum calcium, phosphate, and intact parathyroid hormone levels in older patients undergoing maintenance hemodialysis: a cohort study in Beijing.

"Conflict of interest statement: The authors declare that there is no conflict of interest."

"Funding: The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by the Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (Code: ZYLX201824)."

"This retrospective cohort study was approved by the Institutional Review Board of Beijing Friendship Hospital, Capital Medical University (approval number: BJFH-EC/2016-P2-126-02) and was performed in accordance with the principles of the Declaration of Helsinki. Ethical approval, which exempted the study from the need to obtain informed patient consent, was obtained in accordance with Article 39 of China’s regulation on “Ethics review process on human-related biologic and medical research.” The study was registered at [ClinicalTrials.gov identifier: NCT03261154]."