Digestive and Liver Disease 38 (2006) 319–323 Alimentary Tract Seasonal variations in onset of symptoms in Crohn’s disease A. Aratari a,b,* , C. Papi b , B. Galletti c , E. Angelucci a , A. Viscido a , V. D’Ovidio a , A. Ciaco b , M. Abdullahi b , R. Caprilli a a Department of Clinical Sciences, University “La Sapienza”, Rome, Italy b Gastrointestinal Unit, San Filippo Neri Hospital, Rome, Italy c Gastrointestinal Unit, University of L’Aquila, L’Aquila, Italy Received 6 July 2005; accepted 3 October 2005 Available online 10 November 2005 Abstract Background. Seasonal variations in onset of symptoms have been reported in ulcerative colitis but not in Crohn’s disease. Aim. To investigate whether our inflammatory bowel diseases patients presented seasonal variations in onset of symptoms. Patients and methods. Patients with a diagnosis of inflammatory bowel diseases established between 1995 and May 2004, and consecutively observed from June 2003 to May 2004, were included in the study. Onset of symptoms (year, season and month) was recorded. Expected onsets with a uniform distribution during the year were calculated and compared to observed onsets. Statistical analysis: chi-square test, odds ratio (95% confidence interval). Results. Overall 425 inflammatory bowel diseases patients were enrolled. Onset of symptoms (year and season) was established in 353/425 patients (83%; 150 Crohn’s disease; 203 ulcerative colitis). Onset of symptoms in inflammatory bowel diseases patients as a whole occurred more frequently in spring–summer compared to autumn–winter (odds ratio 1.39; 95% confidence interval 1.03–1.87; p < 0.03). This variation was observed in Crohn’s disease (odds ratio 1.59; 95% confidence interval 1.00–2.51; p < 0.05) and a similar trend, although not significant, was observed in ulcerative colitis (odds ratio 1.27; 95% confidence interval 0.86–1.88; p = 0.27). Conclusions. These data indicate that onset of Crohn’s disease symptoms occurred more frequently during spring-summer. A similar trend was observed in ulcerative colitis. Environmental factors, such as associated infections, smoking, use of drugs and seasonal changes in immune function may be responsible for triggering the clinical onset of inflammatory bowel diseases. © 2005 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved. Keywords: Clinical onset; Crohn’s disease; Seasonality; Ulcerative colitis 1. Introduction Inflammatory bowel diseases (IBD) are the result of a complex interaction between genetic susceptibility and stim- ulation by bacterial antigens in the lumen and occasional environmental triggers that damage the mucosal barrier. Sea- sonality, in the onset of symptoms, has been investigated in many diseases to better understand the epidemiology and * Corresponding author at: Department of Clinical Sciences, University of Rome “La Sapienza”, Policlinico Umberto I, Viale del Policlinico 155, 00161 Rome, Italy. Tel.: +39 064 460 009; mobile: +39 329 972 7967; fax: +39 064 463 737. E-mail address: aalisa@tin.it (A. Aratari). pathogenesis. Seasonal variations have been shown to pre- dispose to the development of a number of different diseases, such as deep vein thrombosis [1], heart failure [2], asthma [3], schizophrenia [4], peptic ulcer [5,6], upper gastrointestinal (GI) bleeding [7] and post-operative small bowel obstruction [8]. Seasonal variations in the occurrence of relapse [9–13] and hospital admission [14] have been reported in IBD. In retro- spective studies, flare-ups of ulcerative colitis (UC) occurred more frequently in spring and autumn [9–12]; conversely, relapses of Crohn’s disease (CD) occurred more frequently in autumn, winter and spring [12,13]. Hospital admissions have been reported to occur more often in winter, but no sea- sonality has been reported for emergency admission [14]. 1590-8658/$30 © 2005 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dld.2005.10.002