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Eun Jin Jang 1 Article
Identifying pregnancy episodes and estimating the last menstrual period using an administrative database in Korea: an application to patients with systemic lupus erythematosus
Yu-Seon Jung, Yeo-Jin Song, Jihyun Keum, Ju Won Lee, Eun Jin Jang, Soo-Kyung Cho, Yoon-Kyoung Sung, Sun-Young Jung
Epidemiol Health. 2024;46:e2024012.   Published online December 19, 2023
DOI: https://doi.org/10.4178/epih.e2024012
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AbstractAbstract AbstractSummary PDFSupplementary Material
Abstract
OBJECTIVES
This study developed an algorithm for identifying pregnancy episodes and estimating the last menstrual period (LMP) in an administrative claims database and applied it to investigate the use of pregnancy-incompatible immunosuppressants among pregnant women with systemic lupus erythematosus (SLE).
METHODS
An algorithm was developed and applied to a nationwide claims database in Korea. Pregnancy episodes were identified using a hierarchy of pregnancy outcomes and clinically plausible periods for subsequent episodes. The LMP was estimated using preterm delivery, sonography, and abortion procedure codes. Otherwise, outcome-specific estimates were applied, assigning a fixed gestational age to the corresponding pregnancy outcome. The algorithm was used to examine the prevalence of pregnancies and utilization of pregnancy-incompatible immunosuppressants (cyclophosphamide [CYC]/mycophenolate mofetil [MMF]/methotrexate [MTX]) and non-steroidal anti-inflammatory drugs (NSAIDs) during pregnancy in SLE patients.
RESULTS
The pregnancy outcomes identified in SLE patients included live births (67%), stillbirths (2%), and abortions (31%). The LMP was mostly estimated with outcome-specific estimates for full-term births (92.3%) and using sonography procedure codes (54.7%) and preterm delivery diagnosis codes (37.9%) for preterm births. The use of CYC/MMF/MTX decreased from 7.6% during preconception to 0.2% at the end of pregnancy. CYC/MMF/MTX use was observed in 3.6% of women within 3 months preconception and 2.5% during 0-7 weeks of pregnancy.
CONCLUSIONS
This study presents the first pregnancy algorithm using a Korean administrative claims database. Although further validation is necessary, this study provides a foundation for evaluating the safety of medications during pregnancy using secondary databases in Korea, especially for rare diseases.
Summary
Korean summary
임산부의 약물 사용 안전성에 대한 근거 제공을 위해 실제 인구집단에서의 임신 중 약물 치료 안전성을 평가하는 청구자료 기반 연구가 중요하다. 본 연구에서는 국내 청구자료에 적용할 수 있는 임신 정의 및 임신 결과 조작적 정의 알고리즘을 개발하였다. 본 알고리즘은 임신 결과 간의 우선순위를 고려한 계층 구조를 활용하며, 조기 분만 및 초음파 검사 코드 등을 통해 최종 월경 기간을 추정하였다. 또한 알고리즘을 전신홍반루푸스 환자에 적용하여 유산, 사산 등의 유병률을 산출하고 임신 중 잠재적으로 부적절한 면역억제제 사용을 파악하여 국내 청구자료의 특성을 고려한 임신 중 약물 사용 연구의 기반을 마련하였다.
Key Message
Limited safety data for pregnant women prompted recent studies on medication during pregnancy using real-world databases. This study developed a tailored algorithm for Korean healthcare claims database, employing a hierarchy of pregnancy outcomes and incorporating pre-term delivery and sonography codes for last menstrual period estimation. Applied to systemic lupus erythematosus (SLE) patients, this study presented the prevalence and drug utilization pattern of pregnancy-incompatible immunosuppressants from preconception to pregnancy end, laying a foundation for further claims database studies on medication pregnancy safety.

Epidemiol Health : Epidemiology and Health