Methods
The data of this national
retrospective cohort study was retrieved from the Taiwan National Health
Insurance Research Database (NHIRD) released by the Taiwan National
Health Research Institutes. The National Health Insurance system is a
mandatory universal health insurance program that offers comprehensive
medical care coverage to nearly all Taiwan residents since the inception
of the program in March 1995. In the NHIRD, the patients’ original
identification numbers are encrypted and the encrypting procedure is
consistent, so that linking claims belonging to the same enrollee is
feasible and can be followed longitudinally. The available health care
information included complete outpatient visits, hospitalization, and
diseases, which were registered using International Classification of
Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)
codes.18 In addition, medication prescriptions are
also recorded. Patients with newly diagnosis of AF and VTE were included
in this study. The study was approved by the Institutional Review Board
of Chang Gung Memorial Hospital (201900915B1).