Data source
SECONDARY, DISEASES
This study was conducted using the Shanghai Link Healthcare Database (SLHD), a representative clinical database covering ＞99% of the residents, developed and operated by the Shanghai Hospital Development Center (an administrative department of the Shanghai Municipal People's Government). In China, government‐run hospitals are classified as primary (grade I), secondary (grade II), and tertiary (grade III) hospitals according to their capabilities in medical care, medical education, and medical research, with tertiary hospitals being the best. The Shanghai Hospital Development Center is responsible for monitoring 35 tertiary hospitals, all of which are required by administrative regulations to upload general medical practice data (i.e., outpatient visits, emergency department visits, and hospital admissions) to the SLHD. The SLHD has released data for academic research since 2013, which requires review and approval to access. Mortality data were obtained from the Shanghai Big Data Center.Any personally identifiable information was scrambled to protect privacy, so the study was exempt from institutional review board approval because the researchers were blinded to patient identities. All diseases were identified according to the 