Current status of testing intervals for antiphospholipid syndrome testing: a 13-year retrospective national data analysis in South Korea.

OBJECTIVE To assess the appropriateness of laboratory testing intervals and antiphospholipid syndrome (APS) incidence. METHODS Between January 2010 and August 2022, insurance claims data of patients with disease codes for other thrombophilia (D68.6) and APS (V253) were retrieved in South Korea. Patients who received antiphospholipid antibody tests more than twice were classified as having suspected APS. The interval between the first 2 antiphospholipid antibody tests was evaluated in the patients with suspected APS. Patients with suspected APS who received anticoagulants for >180 days were classified as having APS. RESULTS Overall, 8656 patients were classified as having suspected APS. The testing interval for the first 2 tests in patients with suspected APS was <6 and <12 weeks in 11.1% and 20.6% of cases, respectively, in 2010, gradually increasing to 21.0% and 35.4%, respectively, in 2021. Subsequently, 4344 patients were classified as having APS, with 65.0% being female. Only 330 patients were diagnosed with APS in 2021, down from 436 in 2020. CONCLUSION This study showed a gradual increase in patients receiving antiphospholipid antibody testing with an inappropriate short-term interval, underscoring the need for laboratory stewardship to ensure an appropriate interval for APS testing.