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©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
Crohn’s disease environmental factors in the developing world: A case-control study in a statewide catchment area in Brazil
Valéria Cristina Loureiro Salgado, Ronir Raggio Luiz, Neio Boechat, Bianca C Schorr, Isabella S Leão, Tiago Nunes, Cyrla Zaltman
Valéria Cristina Loureiro Salgado, Bianca C Schorr, Isabella S Leão, Cyrla Zaltman, Division of Gastroenterology, Department of Internal Medicine, Clementino Fraga Filho Hospital, Federal University of Rio de Janeiro, Rio de Janeiro 21941-913, Brazil
Ronir Raggio Luiz, Institute for Studies in Public Health, Federal University of Rio de Janeiro, Rio de Janeiro 21941-913, Brazil
Neio Boechat, Multidisciplinary Research Laboratory, Clementino Fraga Filho University Hospital, Institute of Thoracic Diseases, Faculty of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro 21941-913, Brazil
Tiago Nunes, Gastrointestinal Physiology, Institute of Nutritional Science, Nestle Research Center, Route du Jorat 57, 1000 Lausanne, Switzerland
Author contributions: Zaltman C provided financial support for this work; Salgado VCL, Boechat N and Zaltman C designed the study; Salgado VCL and Zaltman C coordinated and provided the collection of all data; Leão IS, Schorr BC and Salgado VCL made the structured interviews and collected patient’s data from clinical reports if needed; Salgado VCL and Luiz RR organized and analyzed the data; Nunes T, Salgado VCL and Zaltman C were involved in writing and editing the manuscript; all authors read and approved the final manuscript.
Institutional review board statement: The Study was reviewed and approved by the Comitê de Ética em Pesquisa em Seres Humanos do HUCFF/UFRJ, the Institutional Review board.
Informed consent statement: On behalf of all co-authors I declare that all study participants, or their legal guardian , provided informed written consent prior to study enrolment.
Conflict-of-interest statement: Nunes T is an employee of Nestec SA, Switzerland. The remaining authors disclose no conflicts.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Dr. Cyrla Zaltman, Division of Gastroenterology, Department of Internal Medicine, Clementino Fraga Filho Hospital, Federal University of Rio de Janeiro, Rua Prof. Rodolpho Paulo Rocco 255, Ilha do Fundão, Rio de Janeiro 21941-913, Brazil.
c.zaltman@gmail.com
Telephone: +55-21-39382669 Fax: +55-21-39382669
Received: March 14, 2017
Peer-review started: March 14, 2017
First decision: April 20, 2017
Revised: May 10, 2017
Accepted: July 4, 2017
Article in press: July 4, 2017
Published online: August 14, 2017
Processing time: 153 Days and 3.6 Hours
AIM
To identify environmental risk factors associated with the development of Crohn’s disease (CD) in order to re-assess the hygiene hypothesis.
METHODS
A hospital-based, case-control study was carried out with CD patients (n = 145) and controls (n = 163) representing a socioeconomically diverse statewide catchment area in Brazil. Controls were recruited from caregivers of patients seen in different outpatient clinics at the same hospital. A multi-item survey with 94 questions regarding family history of CD, perinatal and childhood circumstances, living conditions, tobacco use and familial socioeconomic status was carried out by interviewers.
RESULTS
On the univariate analysis, predictive variables for CD included being male, under age of 40, a high education level, urban dweller, smaller family size, exposure to enteric pathogens and user of treated water (P < 0.005). On the multivariate analysis, variables significantly associated with CD were male gender (OR = 2.09), under age 40 (OR = 3.10), white (OR = 2.32), from a small family in childhood (OR = 2.34) and adulthood (OR = 3.02), absence of viral infections in childhood (OR = 2.23), exposure to enteric pathogens (OR = 2.41), having had an appendectomy (OR = 2.47) and prior or current smoker (OR = 2.83/1.12).
CONCLUSION
Most variables supporting the “hygiene hypothesis” are associated with the development of CD but are not independent predictors of the diagnosis.
Core tip: This case-control study aimed to revisit the hygiene hypothesis in inflammatory bowel disease with the inclusion of Crohn’s disease (CD) patients and healthy controls representing a socioeconomically diverse statewide catchment area in Brazil. Subjects completed an extensive 94-item survey regarding perinatal and childhood circumstances, living conditions, smoking and familial socioeconomic status. Most variables supporting the hygiene hypothesis were associated with CD but were not independent predictors of the diagnosis. These findings suggest that, albeit there is an association, the influence that these variables might have on disease development is not as strong as other classic environmental factors (smoking) found to be closely related to disease onset and progression.
