Atopic diseases and the risk of alopecia areata among pre-teens and teenagers in Taiwan.

Background Alopecia areata (AA), a disorder of non-scarring hair loss with a variable relapsing and remitting course, is a common autoimmune disease in children. Although it often presents as several focal small patchy bald lesions, early onset AA can lead to a total loss of scalp hair, even body hairs, a severe subtype. Atopic diseases are common concurrent disorders in AA, especially among those with early onset severe type of hair loss. Whether atopic diseases increase the risk of AA in the paediatric population of Taiwan, remains unclear. Objective To identify if atopic diseases increase the risk of AA among pre-teens and teenagers in Taiwan. Methods From Taiwan National Health Insurance Database 2010, we used the claims data to clarify the risk of AA in pre-teens and teenagers with atopic diseases (atopic dermatitis, allergic conjunctivitis, asthma, allergic rhinitis and food allergy) as compared to the general population. Cox proportional hazards model yielded hazard ratios (HRs) to address the impact of atopic diseases, sex and age on AA risk after adjusting for covariates and subsequent stratified analyses. Results Overall, 21,070 children (10,535 patients with atopic diseases and 10,535 normal cohort) aged over nine years were recruited. During a follow-up of 15 years, 39 (0.37%) cases were identified to have AA in the atopic diseases group, while 11 (0.10%) had developed AA in the normal cohort. As compared with the normal population, the paediatric population with atopic diseases had a 9.66-fold higher risk of developing AA. The risk was greater for boys and increased with advanced age. In the atopic diseases group, pre-teens and teenagers with food allergies and Sjogren's syndrome were more likely to have AA. Limitations Only one ethnic group. Conclusion All atopic diseases enhanced the risk of developing AA in Taiwan pre-teens and teenagers. Children with atopic diseases should be monitored to look for the development of AA.