Observational Study
Copyright ©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 21, 2023; 29(23): 3688-3702
Published online Jun 21, 2023. doi: 10.3748/wjg.v29.i23.3688
Spatial cluster mapping and environmental modeling in pediatric inflammatory bowel disease
Mielle Michaux, Justin M Chan, Luke Bergmann, Luis F Chaves, Brian Klinkenberg, Kevan Jacobson
Mielle Michaux, Justin M Chan, Kevan Jacobson, Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Faculty of Medicine, British Columbia Children’s Hospital, University of British Columbia, Vancouver V6H 3V4, British Columbia, Canada
Mielle Michaux, Justin M Chan, Kevan Jacobson, British Columbia Children’s Hospital Research Institute, British Columbia Children’s Hospital, Vancouver V5Z 4H4, British Columbia, Canada
Luke Bergmann, Brian Klinkenberg, Department of Geography, University of British Columbia, Vancouver V6T 1Z2, British Columbia, Canada
Luis F Chaves, Department of Environmental and Occupational Health, School of Public Health, Indiana University, Bloomington, IN 47405, United States
Kevan Jacobson, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver V6T 1Z3, British Columbia, Canada
Author contributions: Michaux M participated in designing the study, acquisition, analysis, and interpretation of the data, and drafted the initial manuscript; Chan JM participated in designing the study, acquisition, analysis, and interpretation of the data, and revised the article critically for important intellectual content; Bergmann L and Chaves LF participated in the acquisition, analysis, and interpretation of the data, and revised the article critically for important intellectual content; Klinkenberg B participated in designing the study and revised the article critically for important intellectual content; Jacobson K was the guarantor and participated in designing the study, analysis, and interpretation of the data, and revised the article critically for important intellectual content.
Institutional review board statement: The study was reviewed and approved by the University of British Columbia Children’s and Women’s Research Ethics Board (Vancouver), No. H19-00739.
Conflict-of-interest statement: Dr. Jacobson reports other from BC Children’s Hospital Research Institute Clinician Scientist Awards Program Award, grants from Janssen, non-financial support from adMare Bioinnovations, other from Engene, outside the submitted work; and has served on the advisory boards of Janssen, AbbVie, Merck, Amgen, Mylan Inc, and McKesson.
Data sharing statement: Data is available upon reasonable request to the corresponding author subject to research ethics board approval, at kjacobson@cw.bc.ca.
STROBE statement: The authors have read the STROBE Statement—checklist of items, and the manuscript was prepared and revised according to the STROBE Statement—checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (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: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Kevan Jacobson, AGAF, FRCPC, MBChB, Professor, Senior Scientist, Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Faculty of Medicine, British Columbia Children’s Hospital, University of British Columbia, 4480 Oak Street, Room K4-184, Vancouver V6H 3V4, British Columbia, Canada. kjacobson@cw.bc.ca
Received: February 7, 2023
Peer-review started: February 7, 2023
First decision: March 20, 2023
Revised: March 31, 2023
Accepted: April 23, 2023
Article in press: April 23, 2023
Published online: June 21, 2023
ARTICLE HIGHLIGHTS
Research background

Geospatial patterning has been observed in inflammatory bowel disease (IBD) incidence and linked to environmental determinants of disease. However, knowledge of North American IBD spatial patterns is limited, and unknown in pediatric IBD (PIBD). A further understanding of geospatial patterns of IBD will help guide distribution of healthcare services and aid in identifying potential environmental risk and protective factors and populations at risk.

Research motivation

There is a lack of knowledge of the spatial distribution and environmental exposures relevant to PIBD in Canada and specifically in the Canadian province of British Columbia (BC).

Research objectives

The main objectives of this study were (1) To determine spatial patterning of PIBD and identify location of disease hot and cold spots in the Canadian province of BC during the period of 2001–2016; and (2) to model the association between IBD case counts and population-level ethnicity, average income, rural residence, and known as well as novel environmental determinants. Both objectives were addressed using the methods described below.

Research methods

The Moran’s I statistic was used as a Local Indicator of Spatial Association to measure the degree, location, and type of geographic clustering of PIBD incidence, a method which improves on visual analysis of mapped incidence by empirically quantifying clustering. Statistical significance of observed clusters was approximated using Monte Carlo simulation. Case counts of IBD, Crohn’s disease (CD), and ulcerative colitis (UC) were modeled in Poisson rate models as a function of average population characteristics and average population environmental exposures to assess associations between IBD and rurality, ethnicity, income, family size, and air pollution, green space, ultraviolet (UV) light, and pesticide exposures. Data sources included a BCCH clinical registry of patients diagnosed with IBD ≤ age 16.9, high-quality national environmental exposure datasets developed for health research, and Canadian census data.

Research results

No high incidence hot spots were detected in the densest urban areas, suggesting unexplored urban protective factors. Rurality was negatively associated with UC. Novel risk factors for PIBD and specifically CD included fine particulate matter (PM2.5) pollution and agricultural applications of petroleum oil to orchards and grapes. Spatial distribution was partially explained by rurality, population ethnicity, family size, pesticide applications, air pollution, UV exposure, and residential greenness.

Research conclusions

Pesticide and PM2.5 exposure are linked to the development of PIBD. Suburban and low-density urban areas of BC appear to lack protective exposures conferred by rural and dense urban areas.

Research perspectives

Exploring geographic patterns of PIBD facilitated the identification of novel environmental determinants, which has prompted followup studies of environmental exposures and IBD onset.