Retrospective Study of Newly Diagnosed SLE Patients

Patients newly diagnosed with SLE between January 2009 and December 2019 at a tertiary referral hospital in Seoul, South Korea, were retrospectively included in the study. All patients fulfilled the 2012 Systemic Lupus International Collaborating Clinics (SLICC) classification criteria for SLE^{20 (link)}. Patients who were followed up for less than a year were excluded. The retrospective observation period was from the date of SLE diagnosis to the last follow-up date, up to December 2021 or the date of first flare, whichever came first. The following data at the time of diagnosis of SLE were reviewed: age, sex, clinical manifestations of SLE, positivity of anti-dsDNA Ab, anti-Sm Ab, anti-U1RNP Ab, anti-Ro Ab, and anti-La Ab, levels of C3 and C4, and the SLE Disease Activity Index 2000 (SLEDAI-2 K)^{21 (link)}. All patients who had symptoms or signs compatible to SLE and were positive for ANA were uniformly tested for anti-dsDNA, anti-Sm, anti-U1RNP, anti-Ro, and anti-La Abs. Therefore, there were no missing data on the positivity for each autoantibody. The positivity of anti-dsDNA Ab and anti-ENA Abs was tested using an automated fluoroimmunoassay analyzer (EliA; Phadia, Uppsala, Sweden). The use of the following medications during the observation period was reviewed: hydroxychloroquine, glucocorticoid, cyclophosphamide, mycophenolate mofetil, azathioprine, methotrexate, cyclosporin, and tacrolimus.
This study was approved by the Institutional Review Board of Gangnam Severance Hospital (No. 3–2020-0114). The requirement for informed consent was waived by the Institutional Review Board of Gangnam Severance Hospital due to the retrospective nature of this study. This study conformed the ethical guidelines laid out by the 1964 Helsinki declaration.