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
Processing time: 128 Days and 14.8 Hours
Abstract
BACKGROUND

Geographical (geospatial) clusters have been observed in inflammatory bowel disease (IBD) incidence and linked to environmental determinants of disease, but pediatric spatial patterns in North America are unknown. We hypothesized that we would identify geospatial clusters in the pediatric IBD (PIBD) population of British Columbia (BC), Canada and associate incidence with ethnicity and environmental exposures.

AIM

To identify PIBD clusters and model how spatial patterns are associated with population ethnicity and environmental exposures.

METHODS

One thousand one hundred eighty-three patients were included from a BC Children’s Hospital clinical registry who met the criteria of diagnosis with IBD ≤ age 16.9 from 2001–2016 with a valid postal code on file. A spatial cluster detection routine was used to identify areas with similar incidence. An ecological analysis employed Poisson rate models of IBD, Crohn’s disease (CD), and ulcerative colitis (UC) cases as functions of areal population ethnicity, rurality, average family size and income, average population exposure to green space, air pollution, and vitamin-D weighted ultraviolet light from the Canadian Environmental Health Research Consortium, and pesticide applications.

RESULTS

Hot spots (high incidence) were identified in Metro Vancouver (IBD, CD, UC), southern Okanagan regions (IBD, CD), and Vancouver Island (CD). Cold spots (low incidence) were identified in Southeastern BC (IBD, CD, UC), Northern BC (IBD, CD), and on BC’s coast (UC). No high incidence hot spots were detected in the densest urban areas. Modeling results were represented as incidence rate ratios (IRR) with 95%CI. Novel risk factors for PIBD included fine particulate matter (PM2.5) pollution (IRR = 1.294, CI = 1.113-1.507, P < 0.001) and agricultural application of petroleum oil to orchards and grapes (IRR = 1.135, CI = 1.007-1.270, P = 0.033). South Asian population (IRR = 1.020, CI = 1.011-1.028, P < 0.001) was a risk factor and Indigenous population (IRR = 0.956, CI = 0.941-0.971, P < 0.001), family size (IRR = 0.467, CI = 0.268-0.816, P = 0.007), and summer ultraviolet (IBD = 0.9993, CI = 0.9990–0.9996, P < 0.001) were protective factors as previously established. Novel risk factors for CD, as for PIBD, included: PM2.5 air pollution (IRR = 1.230, CI = 1 .056-1.435, P = 0.008) and agricultural petroleum oil (IRR = 1.159, CI = 1.002-1.326, P = 0.038). Indigenous population (IRR = 0.923, CI = 0.895–0.951, P < 0.001), as previously established, was a protective factor. For UC, rural population (UC IRR = 0.990, CI = 0.983-0.996, P = 0.004) was a protective factor and South Asian population (IRR = 1.054, CI = 1.030–1.079, P < 0.001) a risk factor as previously established.

CONCLUSION

PIBD spatial clusters were identified and associated with known and novel environmental determinants. The identification of agricultural pesticides and PM2.5 air pollution needs further study to validate these observations.

Keywords: Inflammatory bowel diseases; Crohn disease; Ulcerative colitis; Pesticides; Air pollution; South Asian people

Core Tip: Utilizing spatial mapping methodology, high and low incidence clusters of pediatric inflammatory bowel disease (IBD) were identified in British Columbia, Canada. Associating geographical location with IBD, rurality was negatively associated with ulcerative colitis. Notably, no high incidence hot spots were detected in the densest urban areas, suggesting unexplored urban protective factors. Novel risk factors for PIBD and specifically Crohn’s disease included fine particulate matter 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, ultraviolet exposure, and residential greenness.