Incidence of pregnancy‐associated venous thromboembolism in Korea: from the Health Insurance Review and Assessment Service database

Pregnancy and the puerperium are well-established risk factors for venous thromboembolism (VTE). During pregnancy, it is estimated that the incidence of VTE is between10–20 events per 10 000 [1–7]. Although the actual incidence of pregnancyassociated VTE is very low, VTE accounts for 1.1 deaths per 100 000 deliveries, which is 5–10% of all maternal deaths [5]. Thus, pregnancy-associated VTE represents a major maternal health problem worldwide. Most previous studies regarding pregnancy-associated VTE were conducted in Caucasian populations. In spite of the clinical significance of pregnancy-associatedVTE, a nationwide epidemiologic study has never been conducted in an Asian population. This is probably because VTE occurs infrequently during pregnancy and the incidence of VTE in Asian populations has generally been lower than that in Caucasian populations [8]. Therefore, a nationwide epidemiologic study was performed that used the Korean Health Insurance Review and Assessment Service (HIRA) database to provide basic information regarding the incidence of pregnancy-associated VTE. Recently, we reported that the incidence of VTE in the Korean population is approximately one-tenth to one-fifth of that reported in the Caucasian population [8]. As an extension of the epidemiologic study that investigated the difference between ethnicities, we carried out the pregnancy-associated VTE study in the Korean population using the Korean Health Insurance Review and Assessment Service (HIRA) database to provide basic information regarding the incidence of pregnancy-associated VTE. HIRA is a government-affiliated organization that builds an accurate claims review and quality assessment system for the National Health Insurance [9]. All pregnancy-associated VTE cases were included when both diagnostic codes according to the Korean Classification of Disease, fifth edition and medication codes, for example I80.2 [deep vein thrombosis (DVT), not otherwise specified (NOS)], I80.3 (embolism or thrombosis of the lower extremity, NOS), I26 [pulmonary thromboembolism (PE)], I26.0 (PE with a mention of acute cor pulmonale), I26.9 (PE, NOS), O87.1 (DVT, postpartum) and O88 (obstetric embolism) were simultaneously identified. A total of 147 cases of pregnancy-associated VTE were identified in the Korean population during the 5-year period (2006–2010) examined. The distribution by age group (in descending frequency) was as follows: 30–34 years, 39.4%; 25– 29 years, 32.6%; 35–39 years, 20.4%; 15–24 years, 4.1%; ‡ 40 years, 3.4%. Eighty patients (54.5%) were nulliparous, whereas 67 patients (45.6%) were multiparous. With regard to the type of delivery, 69 patients (46.9%) had a vaginal delivery and 78 patients (53.1%) had a cesarean section. Four patients (2.7%) had multiple pregnancies, two patients (1.4%) had premature rupture of the membranes and two patients (1.4%) had preeclampsia/eclampsia. Forty-four (29.9%) and 103 (70.1%) patients were diagnosed with antenatal and postnatal VTE, respectively. During the 5-year study period, there were 1 795 064 deliveries in Korean. Thus, the total incidence of pregnancyassociated VTE was 0.82 (per 10 000 deliveries) [95% confidence interval (CI), 0.69–0.96]. The annual incidence of pregnancy-associated VTE was 0.70 in 2006, 0.58 in 2007, 0.72 in 2008, 1.04 in 2009 and 1.06 in 2010 (Fig. 1A). These data indicate that the incidence of pregnancy-associated VTE increased steadily from 2007 to 2010. The incidence of pregnancy-associated VTE (per 10 000 deliveries) was 0.47 (95%CI, 0.17–1.03) at 15–24 years of age, 0.71 (95%CI, 0.52– 0.94) at 25–29 years of age, 0.76 (95% CI, 0.57–0.98) at 30– 34 years of age, 1.47 (95%CI, 0.99–2.10) at 35–40 years of age and 2.33 (95%CI, 0.76–5.43) at over 40 years of age. The odds ratio (OR) for VTEwas 1.07 (95%CI, 0.73–1.57; P = 0.73) at 30–34 years of age, 2.08 (95%CI, 1.32–3.28;P = 0.002) at 35– 40 years of age and 3.29 (95%CI, 1.31–8.26;P = 0.01) at over 40 years of age. Correspondence: Doyeun Oh, Department of Internal Medicine, School of Medicine, CHA University, 351 Yatap-dong, Bundang-gu, Seongnam, Gyeonggido 463-712, South Korea. Tel.: +82 31 780 5217; fax: +82 31 780 5208. E-mail: doh@cha.ac.kr