Geographical variation of Crohn's disease residual incidence in the Province of Quebec, Canada.
BACKGROUND
Crohn's disease (CD) is clinically expressed as a chronic affection of the gastrointestinal tract currently known to have a multifactorial etiology involving a complex pathophysiological host response modulated by genetic susceptibilities, demographic determinants and environmental factors. With more than 20 cases per 100,000 person-years, the province of Quebec, Canada is among regions of the world with highest reported occurrence of CD in relation to other places where comparable estimates are available. This ecological study was designed to provide a medium-scale spatial exploration of CD incidence after accounting for the influence of known population and regional determinants. Health records of consulting patients in southern Quebec were compiled from 1995 to 2000 and used to estimate age and sex standardized rates per health area (n = 156). Various statistical models taking into account the regional effect of Jewish ethnicity, aboriginal ancestry, material deprivation, prescription for oral contraceptives, reportable enteric infection incidence, smoking as well as latitude and longitude locations were fitted.


RESULTS
The final regression model presented a coefficient of determination of 22.8% and there was evidence of an eastern trend in the residual incidence (p = 0.018). Overall, the smoothed residual incidence presented a heterogeneous spatial pattern with evidence of patches (multiple health areas) of high, low and contrasting values. Health areas with most extreme incidence residuals where also distributed over the whole province including one area in the metropolitan area of Montreal and others in surrounding areas.


CONCLUSIONS
These findings suggest that known populational and regional factors derived through census information only explain a limited fraction of the geographical variation of CD incidence and lead to speculate that the effects of these factors may be incompletely captured (imperfect construction of proxy variables) or that other important factors remain unmeasured. In this view, markers of genetic profiles of homogeneous sub-populations, and other factors linked to agroenvironmental microbial exposure should be further investigated. Once accounting for known factors, it would also be worth comparing adjacent geographical areas demonstrating abrupt changes in residual incidence rates to further explore effect linked to regional factors from those resulting from various reporting systems.
Michel
Pascal
P
Laboratory for Foodborne Zoonoses, Public Health Agency of Canada, Saint-Hyacinthe, Quebec, Canada. pascal_michel@phac-aspc.gc.ca
St-Onge
Laurie
L
Lowe
Anne-Marie
AM
Bigras-Poulin
Michel
M
Brassard
Paul
P
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D003424:Crohn Disease / Q000453:epidemiology* / Q000208:ethnology / Q000235:genetics; D003710:Demography; D004781:Environmental Exposure / Q000009:adverse effects / Q000706:statistics & numerical data*; D005006:Ethnicity / Q000706:statistics & numerical data*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016012:Poisson Distribution; D011237:Predictive Value of Tests; D011336:Probability; D011792:Quebec / Q000453:epidemiology; D012044:Regression Analysis; D012189:Retrospective Studies; D018570:Risk Assessment; D017678:Sex Distribution; D055815:Young Adult
Curr Opin Gastroenterol. 2008 Jan;24(1):17-21
18043227
Best Pract Res Clin Gastroenterol. 2009;23(2):233-43
19414149
Aliment Pharmacol Ther. 2002 Nov;16(11):1903-15
12390099
Med Sci (Paris). 2007 Nov;23(11):997-1001
18021714
J Gastroenterol Hepatol. 2008 Dec;23(12):1794-801
19120872
Orv Hetil. 2005 Apr 24;146(17):797-802
17918636
Scand J Gastroenterol. 2008 Aug;43(8):961-6
19086166
Am J Epidemiol. 1999 May 15;149(10):916-24
10342800
Am J Gastroenterol. 2001 Apr;96(4):1101-5
11316154
Inflamm Bowel Dis. 2006 Jan;12 Suppl 1:S3-9
16378007
Am J Phys Anthropol. 2009 Aug;139(4):512-22
19226649
Am J Epidemiol. 2001 Aug 15;154(4):328-35
11495856
Environ Health Perspect. 2008 Aug;116(8):1098-104
18709174
Clin Genet. 2005 Oct;68(4):287-301
16143014
Am J Epidemiol. 2008 Nov 1;168(9):1065-72
18801890
Med Hypotheses. 2009 Jul;73(1):94-6
19269107
Inflamm Bowel Dis. 2010 May;16(5):807-12
19774647
Eur Heart J. 1999 Dec;20(23):1689-91
10562474
Ann Agric Environ Med. 2008;15(2):193-7
19061254
Curr Pharm Des. 2009;15(18):2074-86
19519445
Inflamm Bowel Dis. 2009 Mar;15(3):429-35
18942744
Am J Gastroenterol. 2009 Sep;104(9):2233-40
19513023
Annu Rev Genomics Hum Genet. 2001;2:69-101
11701644
Curr Opin Gastroenterol. 2009 Jul;25(4):301-5
19349861
J Dig Dis. 2009 Feb;10(1):1-6
19236540
Inflamm Bowel Dis. 2006 Mar;12(3):212-7
16534423
Am J Gastroenterol. 2006 Jul;101(7):1559-68
16863561
Indian J Med Res. 2009 Aug;130(2):133-7
19797809
J Clin Epidemiol. 2005 Feb;58(2):206-8
15680756
Scand J Gastroenterol. 2006 Apr;41(4):437-44
16635912
World J Gastroenterol. 2009 Jun 7;15(21):2570-8
19496185
Am J Epidemiol. 2006 Oct 1;164(7):615-23; discussion 624-8
16920784
Pharmacoepidemiol Drug Saf. 2006 Jan;15(1):19-29
16136613
World J Gastroenterol. 2010 Jan 28;16(4):431-8
20101767
Inflamm Bowel Dis. 2009 Apr;15(4):608-15
19067408
World J Gastroenterol. 2009 May 7;15(17):2081-8
19418580
Curr Opin Gastroenterol. 2008 Jul;24(4):440-7
18622157
Inflamm Bowel Dis. 2006 Mar;12(3):218-26
16534424
Inflamm Bowel Dis. 2008 Jul;14(7):984-91
18338775