Prevalence of osteoporosis among North Korean women refugees living in South Korea: a comparative cross-sectional study.

OBJECTIVE To investigate the prevalence of osteoporosis among North Korean women refugees when compared with South Korean women, who have identical genetic backgrounds but experience different environments. DESIGN Comparative cross-sectional study. SETTING North Korean Refugee Health in South Korea (NORNS) study in South Korea. PARTICIPANTS We evaluated 122 North Korean women who participated in NORNS study and 366 age-matched/menopausal status-matched South Korean women from the Korea University Medical Center (KUMC) health examination cohort. The median age of the NORNS participants was 46 years (IQR, 40-60 years) with 52 women (42.6%) being postmenopausal. RESULTS Among the postmenopausal women, NORNS participants had a higher body mass index and number of pregnancies and lower physical activity than the KUMC participants. The overall prevalence of osteoporosis was 48% (25/52) and 17% (27/156) in NORNS and KUMC participants, respectively. The bone mineral density (BMD) values at the lumbar spine, femur neck and total hip were significantly lower in postmenopausal NORNS women than in the postmenopausal KUMC women. Old age, low body weight and late age of menarche were associated with low BMD among the postmenopausal North Korean refugees. In premenopausal participants, the NORNS women had lower body weight and physical activity than the KUMC women at baseline. All the NORNS women had normal Z-scores, although the BMD at the lumbar spine was significantly lower in NORNS women than in the KUMC women (0.952 vs 1.002 g/cm2, p<0.001). CONCLUSIONS Osteoporosis is a prevalent health problem in postmenopausal North Korean women refugees living in South Korea. It is conceivable to prepare vigilant countermeasures for bone health deterioration in this growing population, especially for postmenopausal women. Further research is warranted to determine the cause of the differences between participants of the same ethnic group.