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The relationship between urban environment and the inflammatory bowel diseases: a systematic review and meta-analysis Full Text
BMC Gastroenterology, 06/21/2012
Clinical Article
Soon IS et al. – A positive association between urban environment and both Crohn's disease (CD) and ulcerative colitis (UC) was found. Heterogeneity may be explained by differences in study design and quality factors.
Methods- A systematic literature search of MEDLINE (1950-Oct. 2009) and EMBASE (1980-Oct. 2009) was conducted to identify studies investigating the relationship between urban environment and IBD.
- Cohort and case-control studies were analyzed using incidence rate ratio (IRR) or odds ratio (OR) with 95 % confidence intervals (CIs), respectively.
- Stratified and sensitivity analyses were performed to explore heterogeneity between studies and assess effects of study quality.
- The search strategy retrieved 6940 unique citations and 40 studies were selected for inclusion.
- Of these, 25 investigated the relationship between urban environment and UC and 30 investigated this relationship with CD.
- Included in the analysis were 7 case-control UC studies, 9 case-control CD studies, 18 cohort UC studies and 21 cohort CD studies.
- Based on a random effects model, the pooled IRRs for urban compared to rural environment for UC and CD studies were 1.17 (1.03, 1.32) and 1.42 (1.26, 1.60), respectively.
- These associations persisted across multiple stratified and sensitivity analyses exploring clinical and study quality factors.
- Heterogeneity was observed in the cohort studies for both UC and CD, whereas statistically significant heterogeneity was not observed for the case-control studies.
