Study design
To protect individual privacy, the original identification numbers of
the beneficiaries’ data were encrypted for privacy. Encryption
procedures were consistent with other datasets and ensured that all
claims data could be linked in order to obtain additional medically
relevant data. All data that could be used to identify patients or care
providers, including the names of medical institutions and physicians,
were encrypted. Patients with RA (the international classification of
diseases, ninth revision (ICD-9) with 714.0) in the LHID 2005 were
initially screened. We confirmed RA diagnosis using catastrophic illness
certification (CIC) according to the NHI program regulations [3, 4].
Therefore, all RA diagnoses required the agreement of two
rheumatologists, one application rheumatologist and one anonymous senior
rheumatologist as the reviewer. All rheumatologists met the following
two criteria: three-year internal medicine residents training in a
quality hospital, usually a tertiary hospital, and two-year rheumatology
fellow training. “Senior” usually refers to a rheumatologist career
that has spanned at least 10 years.