Brief Article
Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Dec 21, 2013; 19(47): 9063-9068
Published online Dec 21, 2013. doi: 10.3748/wjg.v19.i47.9063
Seasonal variations in the onset of ulcerative colitis in Japan
Shigeo Koido, Toshifumi Ohkusa, Hiroaki Saito, Tetsuji Yokoyama, Tomoyoshi Shibuya, Naoto Sakamoto, Kan Uchiyama, Hiroshi Arakawa, Taro Osada, Akihito Nagahara, Sumio Watanabe, Hisao Tajiri
Shigeo Koido, Toshifumi Ohkusa, Kan Uchiyama, Hiroshi Arakawa, Hisao Tajiri, Division of Gastroenterology and Hepatology, Department of Internal Medicine, the Jikei University School of Medicine, Chiba 277-8567, Japan
Hiroaki Saito, Tomoyoshi Shibuya, Naoto Sakamoto, Taro Osada, Akihito Nagahara, Sumio Watanabe, Department of Gastroenterology, Juntendo University School of Medicine, Tokyo 113-8421, Japan
Tetsuji Yokoyama, Department of Health Promotion, National Institute of Public Health, Saitama 351-0197, Japan
Author contributions: Koido S, Ohkusa T, Saito H, Watanabe S, and Tajiri H designed the research; Koido S, Ohkusa T, Saito H, Yokoyama T, Shibuya T, Sakamoto N, Uchiyama K, Arakawa H, Osada T, and Nagahara A performed the research and analyzed the data; Koido S and Ohkusa T wrote the paper.
Supported by Grants in Aid for Scientific Research (C) from the Japanese Ministry of Education, Culture, Sports, Science, and Technology, No. 23501289
Correspondence to: Shigeo Koido, MD, Division of Gastroenterology and Hepatology, Department of Internal Medicine, the Jikei University School of Medicine, 8 Chome-3-1 Kokuryocho, Chiba 277-8564, Japan. shigeo_koido@jikei.ac.jp
Telephone: +81-4-71641111 Fax: +81-4-71633488.
Received: July 21, 2013
Revised: September 12, 2013
Accepted: September 29, 2013
Published online: December 21, 2013
Abstract

AIM: To investigate seasonal variations in the onset and relapse of ulcerative colitis (UC) in Japanese patients.

METHODS: Between 1994 and 2006, 198 Japanese patients diagnosed with UC according to conventional criteria in an academic hospital were enrolled for onset evaluation. Among 265 Japanese patients with UC who were observed for more than 12 mo, 165 patients relapsed (239 times) and were enrolled for relapse evaluation. The patients’ symptoms were recorded each month for 12 consecutive years.

RESULTS: There was monthly seasonality in symptom onset during October and March for UC. The onset of symptoms in UC patients frequently occurred during the winter. Variation in UC onset was observed according to both month (P = 0.015) and season (P = 0.048). Relapse commonly occurred in October, and variations in relapse were not significant either in month (P = 0.52) or season (P = 0.12). Upper respiratory inflammation was the main factor responsible for relapse.

CONCLUSION: Our results suggest that environmental factors associated with winter and spring seasonality may be responsible for triggering the clinical onset of UC in Japan.

Keywords: Japanese population, Onset, Relapse, Seasonal variations, Ulcerative colitis

Core tip: Monthly seasonality in the symptomatic onset of ulcerative colitis (UC) during October and March was observed in Japan. The onset of symptoms frequently occurred during the winter, whereas relapse of UC particularly occurred in October. Upper respiratory inflammation was one of the main factors responsible for relapse. Therefore, environmental factors associated with winter and spring seasonality may be responsible for triggering the clinical onset of UC in Japan.