High rate of nickel allergy in women with endometriosis: A 3-year population-based study

Aim The aim of this study was to evaluate the prevalence rates of nickel allergy, contact dermatitis, drug allergy, allergic rhinitis and atopic dermatitis among women with and without endometriosis. Material and Methods Data were obtained from the National Patient Sample of the Republic of Korea, which was provided by the Korean Health Insurance Review and Assessment Service. We evaluated women aged 20-40 years who visited a health care institution from 2009-2011. We estimated the prevalence of allergic diseases among women with and without endometriosis. Results We extracted a sample of 1 843 447 women from the total patient sample of approximately 3 million. We identified 7259 women with endometriosis and 535 818 women without endometriosis. After adjusting for age and data year, the women with endometriosis had higher rates of nickel allergy (odds ratio = 1.175; 95% confidence interval, 1.011-1.366; P = 0.04). Additionally, after adjusting for age, data year and other allergic diseases, the women with endometriosis had higher rates of nickel allergy (odds ratio = 1.167; 95% confidence interval, 1.004-1.357; P = 0.04). After adjusting for other covariates, we found that other allergic disorders, such as allergic rhinitis, atopic dermatitis and contact dermatitis, were not associated with endometriosis. Conclusion Women with endometriosis had higher rates of nickel allergy. Further research is required to clarify the relation between nickel allergy and endometriosis.