Background Rheumatoid arthritis (RA) is a chronic inflammatory arthritis with female-predominance, and is 2-4 times more likely to develop in women than in man. Hence, researchers have suggested that immunological aspects of sex hormones may influence the induction of autoimmunity, and several epidemiological studies have tried to find relevant reproduction factors on the development of RA. However, results of these studies are inconsistent and most study populations were Caucasian.
Objectives To investigate the contributions of breastfeeding and other reproductive factor in relation to RA in Korean population.
Methods From the Fifth Korean National Health and Nutrition Examination Surveys (KNHANES V) (2010-2012) dataset, we identified 279 female patients who were diagnosed as RA by physician and ten age-matched female controls for every cases were randomly selected. Data on reproductive factors were derived from a self-administered questionnaire. The relationship between potential risk factors, including smoking, socioeconomic status, breastfeeding, parity, age at first birth, age at menarche, use of oral contraceptives, and use of postmenopausal hormones and RA was estimated using logistic regression models.
Results Two hundred and seventy-nine women with RA were compared with 2790 age-matched controls. The mean age of RA diagnosis was 47.9±15.3 years. Female patients with RA were significantly more likely to have low waist circumference and multiparity. There was no difference in the age at menarche, age at menopause, use of oral contraceptives, and use of postmenopausal hormones between those with and without RA. Among women who had at least one live birth, those who ever breastfed were associated with low risk of having RA after adjusting related risk factors (odds ratio 0.211; 95% CI 0.127-0.349). Also, RA risk was significantly decreased with increasing duration of breastfeeding (Table 1). Neither parity nor use of female hormone drugs had any significant effect on the risk of RA.
Conclusions In this study, breastfeeding was inversely related to having RA, and this effect was significantly related to the duration of breastfeeding in Korean population. Other reproductive factors were not associated with RA risk.
Karlson EW, Mandl LA, Hankinson SE, Grodstein F. Do breast-feeding and other reproductive factors influence future risk of rheumatoid arthritis? Results from the Nurses' Health Study. Arthritis Rheum 2004;50:3458-67.
Marder W, Somers EC. Is pregnancy a risk factor for rheumatic autoimmune diseases? 2014;26:321-8.
Disclosure of Interest None declared
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