Data source
The data form the Taiwan National Health Insurance Research Database (NHIRD) was analyzed in this study. The Taiwan National Health Insurance (NHI) program launched in 1995 and covered 99% of Taiwan residents. The comprehensive claims data form NHI program was collected into NHIRD. We utilized the outpatients and in-patient records of one million beneficiaries, the Longitudinal Health Insurance Database (LHID). The database used the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes to define the corresponding diseases. Due to safety and privacy concerns, the identification information was encrypted. This study was approved by the International Review Board (IRB) of China Medical University and Hospital (IRB permit number: CMUH-104-REC2–115).