Crohn’s disease environmental factors in the developing world: A case-control study in a statewide catchment area in Brazil

Abstract

AIMTo identify environmental risk factors associated with the development of Crohn’s disease (CD) in order to re-assess the hygiene hypothesis.METHODSA 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.RESULTSOn 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).CONCLUSIONMost variables supporting the “hygiene hypothesis” are associated with the development of CD but are not independent predictors of the diagnosis.

Risk factors associated with inflammatory bowel disease: A multicenter case-control study in Brazil

“…Historically, epidemiological studies have reported higher prevalence of the disease in Caucasians than in black and Asian people[ 23 - 25 ]. In the present study, univariate analysis showed that white individuals predominated in the CD group; thus, corroborating a previous study conducted by this team in the state of Rio de Janeiro[ 19 ]. However, the results from the multivariate analysis did not show any statistical significance for CD and UC.…”

“…In Brazil, studies on the incidence and prevalence of inflammatory bowel diseases have been regional, and studies investigating risk factors involved in the development of IBD are lacking[ 19 ]. Historically, the incidence and prevalence of IBD in Brazil have been low as compared with Western countries in Europe, North America, and Australia.…”

Epidemiology of inflammatory bowel disease in South America: A systematic review

“…A case-control study conducted by Salgado et al[18] at a statewide tertiary referral centre in Rio de Janeiro sought to identify envionmental risk factors associated with the development of CD to re-assess the hygeine hypothesis in this unique population. In this study, 145 outpatients with CD were compared to 163 controls by means of a 94-item survey regarding perinatal and childhood circumstances, living conditions, smoking and familial socioeconomic status.…”

“…Controls were were recruited from caregivers of patients seen in different outpatient clinics at the same hospital. On univariate analysis, predictive variables for CD included male gender [Odds ratio (OR) = 2.09, P = 0.003], age under 40 (OR = 2.71, P < 0.001), “white” race (OR = 2.32, P = 0.002), small family in childhood (OR = 2.34, P < 0.006) and adulthood (OR = 3.02, P = 0.002), exposure to enteric pathogens (OR = 2.23, P = 0.001 ), and history of cigarette smoking (OR = 2.83, P = 0.002)[18].…”

“…The hygiene hypothesis postulates that improved hygiene and environmental conditions would reduce the incidence of infections and favour the development of immune-mediated diseases. In this hypothesis, it is thought that exposure to various microbial agents may confer a protective role in promoting immune system maturation by achieving a balance between a pro-inflammatory Th1 response and regulatory T cell tolerance[18,30-32]. This in turn would provide protection against subsequent exposure to antigens and allergens therefore decreasing the likelihood of developing autoimmune conditions such as IBD.…”