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Long-term Health Sequelae Following E.coli and Campylobacter Contamination of Municipal Water

Population Sampling and Assessing Non-participation Biases

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Abstract

Background

Following bacterial contamination of a municipal water system in the rural town of Walkerton, Ontario, over 2,300 cases of acute gastroenteritis were documented. The Walkerton Health Study is currently underway to assess for long-term health sequelae among consenting inhabitants of Walkerton, related to the original outbreak. We explored whether the association between the acute exposure and preliminary long-term health outcomes may have been biased through differences between early- and late-recruited study participants.

Methods

Using multiple data sources, including the 1996 and 2001 Canadian Census, and records from the Regional Health Unit, hospital and Walkerton Health Study, we determined both sample representativeness and the anticipated effects of intensifying study participant recruitment. Selection bias was assessed by examining for differences between initial and late participants, and their subsequent risk of having hypertension, proteinuria and reduced renal clearance.

Results

Of the 4,315 participants, 2,756 were permanent residents of Walkerton, representing 55% of the town’s total population. The sample was demographically similar to the population of interest, although statistically women were more likely to participate than men (55% of sample were women compared to 52% of population, p<0.01), and the proportion of both young and very elderly adults was smaller than expected (13% of sample were >65 years of age compared to 18% of population, p<0.01). Comparing the initial 3,959 participants to the 356 persons additionally recruited with substantial effort, the latter were more likely to be free of symptoms during the outbreak (21% vs. 7%, p<0.001), but were otherwise similar in terms of age, sex, the use of medical care resources and underlying health state predating the outbreak. The risk of long-term hypertension or renal sequelae did not significantly differ between initial and late study recruits.

Conclusions

Participants in the Walkerton Health Study represent the population of interest, and comprise those who were acutely ill during the infected water outbreak. The available study sample should provide reasonably unbiased estimates of the associated risk between acute bacterial gastroenteritis and long-term health sequelae.

Résumé

Contexte

Après la contamination bactérienne du réseau municipal d’alimentation en eau de la collectivité rurale de Walkerton, en Ontario, plus de 2 300 cas de gastro-entérite aiguë ont été documentés. L’Étude sur la santé de Walkerton évalue actuellement les séquelles à long terme de cette flambée épidémique sur la santé des habitantes et des habitants de Walkerton ayant accepté de participer. Nous avons cherché à déterminer si l’association entre l’exposition aiguë et les premiers résultats sanitaires à long terme pouvait comporter des biais en raison des différences entre les recrues initiales et tardives.

Méthode

Nous avons utilisé des données de plusieurs sources, dont les recensements canadiens de 1996 et de 2001 et les dossiers de la circonscription sanitaire, de l’hôpital et de l’Étude sur la santé de Walkerton, pour déterminer la représentativité de l’échantillon et les effets escomptés de l’intensification du recrutement. Pour évaluer le biais de sélection, nous avons cerné les différences entre les recrues initiales et tardives et leur risque ultérieur de souffrir d’hypertension artérielle, de protéinurie et de clairance rénale réduite.

Résultats

Des 4 315 personnes participantes, 2 756 étaient des résidents permanents de Walkerton, soit 55 % de la population de la ville. Sur le plan démographique, l’échantillon était semblable à la population de Walkerton, bien que statistiquement, les femmes aient eu plus tendance à participer que les hommes (l’échantillon comportait 55 % de femmes, alors qu’elles représentent 52 % de la population, p < 0,01), et que les proportions de jeunes et de personnes très âgées aient été plus faibles que prévu (l’échantillon comportait 13 % de personnes de plus de 65 ans, alors qu’elles représentent 18 % de la population, p < 0,01). Si l’on compare les 3 959 recrues initiales aux 356 personnes recrutées plus tard au prix d’un effort considérable, ces dernières étaient plus susceptibles d’avoir été asymptomatiques durant la flambée (21 % c. 7 %, p < 0,001), mais sur tous les autres plans (âge, sexe, recours aux soins médicaux et état de santé avant la flambée), les deux groupes étaient semblables. Le risque d’hypertension artérielle ou de séquelles rénales à long terme ne différait pas de façon significative chez les recrues initiales et tardives de l’étude.

Conclusions

Les participantes et les participants de l’Étude sur la santé de Walkerton sont représentatifs de la population de Walkerton, et ils comprennent les personnes atteintes d’infections aiguës durant la flambée d’origine hydrique. L’échantillon disponible pour l’étude devrait donc fournir des estimations raisonnablement impartiales du risque associé entre la gastro-entérite bactérienne aiguë et les séquelles à long terme sur la santé.

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References

  1. Anonymous. The investigative report of the Walkerton outbreak of waterborne gastroenteritis May–June 2000. Bruce-Grey-Owen Sound Health Unit. 2000;1–67.

    Google Scholar 

  2. Neal KR, Hebden J, Spiller R. Prevalence of gastrointestinal symptoms six months after bacterial gastroenteritis and risk factors for development of the irritable bowel syndrome: Postal survey of patients. BMJ 1997;314(7083):779–82.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  3. Parry SD, Stansfield R, Jelley D, Gregory W, Phillips E, Barton JR, et al. Does bacterial gastroenteritis predispose people to functional gastrointestinal disorders? A prospective, community-based, case-control study. Am J Gastroenterol 2003;98(9):1970–75.

    PubMed  Google Scholar 

  4. Hannu T, Mattila L, Rautelin H, Pelkonen P, Lahdenne P, Siitonen A, et al. Campylobacter-triggered reactive arthritis: A population-based study. Rheumatology (Oxford) 2002;41(3):312–18.

    Article  CAS  Google Scholar 

  5. Bremell T, Bjelle A, Svedhem A. Rheumatic symptoms following an outbreak of campylobac-ter enteritis: A five year follow up. Ann Rheum Dis 1991;50(12):934–38.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  6. Garg AX, Suri RS, Barrowman N, Rehman F, Matsell D, Rosas-Arellano MP, et al. Long-term renal prognosis of diarrhea-associated hemolytic uremic syndrome: A systematic review, meta-analysis, and meta-regression. JAMA 2003;290(10):1360–70.

    Article  CAS  PubMed  Google Scholar 

  7. Suri R, Clark W, Mahon J, Garg AX. Incidence of diabetes mellitus after diarrhea associated hemolytic-uremic syndrome: A systematic review. Submitted for review.

  8. Bertazzi PA. Industrial disasters and epidemiology. A review of recent experiences. Scand J Work Environ Health 1989;15(2):85–100.

    Article  CAS  PubMed  Google Scholar 

  9. Lyons RA, Temple JM, Evans D, Fone DL, Palmer SR. Acute health effects of the Sea Empress oil spill. J Epidemiol Community Health 1999;53(5):306–10.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  10. Ives DG, Traven ND, Kuller LH, Schulz R. Selection bias and nonresponse to health promotion in older adults. Epidemiology 1994;5(4):456–61.

    Article  CAS  PubMed  Google Scholar 

  11. Sheikh K. Predicting risk among non-respondents in prospective studies. Eur J Epidemiol 1986;2(1):39–43.

    Article  CAS  PubMed  Google Scholar 

  12. Statistics Canada Census Operating Division. A profile of the Canadian population: Where we live. Statistics Canada 2004; Catalogue: 96F003XIE0 no1.

    Google Scholar 

  13. Gardner MJ, Altman DG. Statistics with confidence. BMJ 1994;51–52.

    Google Scholar 

  14. Ganguli M, Lytle ME, Reynolds MD, Dodge HH. Random versus volunteer selection for a community-based study. J Gerontol A Biol Sci Med Sci 1998;53(1):M39-M46.

    Google Scholar 

  15. Roht LH, Vernon SW, Weir FW, Pier SM, Sullivan P, Reed LJ. Community exposure to hazardous waste disposal sites: Assessing reporting bias. Am J Epidemiol 1985;122(3):418–33.

    Article  CAS  PubMed  Google Scholar 

  16. Rowland ML, Forthofer RN. Adjusting for non-response bias in a health examination survey. Public Health Rep 1993;108(3):380–86.

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Brick JM, Kalton G. Handling missing data in survey research. Stat Methods Med Res 1996;5(3):215–38.

    Article  CAS  PubMed  Google Scholar 

  18. Korkeila K, Suominen S, Ahvenainen J, Ojanlatva A, Rautava P, Helenius H, et al. Non-response and related factors in a nation-wide health survey. Eur J Epidemiol 2001;17(11):991–99.

    Article  CAS  PubMed  Google Scholar 

  19. Van Loon AJ, Tijhuis M, Picavet HS, Surtees PG, Ormel J. Survey non-response in the Netherlands: Effects on prevalence estimates and associations. Ann Epidemiol 2003;13(2):105–10.

    Article  PubMed  Google Scholar 

  20. Kotaniemi JT, Hassi J, Kataja M, Jonsson E, Laitinen LA, Sovijarvi AR, et al. Does non-responder bias have a significant effect on the results in a postal questionnaire study? Eur J Epidemiol 2001;17(9):809–17.

    Article  CAS  PubMed  Google Scholar 

  21. Brogger J, Bakke P, Eide GE, Gulsvik A. Contribution of follow-up of nonresponders to prevalence and risk estimates: A Norwegian respiratory health survey. Am J Epidemiol 2003;157(6):558–66.

    Article  PubMed  Google Scholar 

  22. Chou P, Kuo HS, Chen CH, Lin HC. Characteristics of non-participants and reasons for non-participation in a population survey in Kin-Hu, Kinmen. Eur J Epidemiol 1997;13(2):195–200.

    Article  CAS  PubMed  Google Scholar 

  23. de Marco R, Verlato G, Zanolin E, Bugiani M, Drane JW. Nonresponse bias in EC Respiratory Health Survey in Italy. Eur Respir J 1994;7(12):2139–45.

    Article  PubMed  Google Scholar 

  24. Buchner DM, Pearson DC. Factors associated with participation in a community senior health promotion program: A pilot study. Am J Public Health 1989;79(6):775–77.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  25. Shahar E, Folsom AR, Jackson R. The effect of nonresponse on prevalence estimates for a referent population: Insights from a population-based cohort study. Atherosclerosis Risk in Communities (ARIC) Study Investigators. Ann Epidemiol 1996;6(6):498–506.

    Article  CAS  PubMed  Google Scholar 

  26. Hill A, Roberts J, Ewings P, Gunnell D. Non-response bias in a lifestyle survey. J Public Health Med 1997;19(2):203–7.

    Article  CAS  PubMed  Google Scholar 

  27. O’Neill TW, Marsden D, Silman AJ. Differences in the characteristics of responders and non-responders in a prevalence survey of vertebral osteoporosis. European Vertebral Osteoporosis Study Group. Osteoporos Int 1995;5(5):327–34.

    Article  PubMed  Google Scholar 

  28. Nakai S, Hashimoto S, Murakami Y, Hayashi M, Manabe K, Noda H. [Response rates and non-response bias in a health-related mailed survey]. Nippon Koshu Eisei Zasshi 1997;44(3):184–91.

    CAS  PubMed  Google Scholar 

  29. Hoeymans N, Feskens EJ, Van Den Bos GA, Kromhout D. Non-response bias in a study of cardiovascular diseases, functional status and self-rated health among elderly men. Age Ageing 1998;27(1):35–40.

    Article  CAS  PubMed  Google Scholar 

  30. Etter JF, Perneger TV. Analysis of non-response bias in a mailed health survey. J Clin Epidemiol 1997;50(10):1123–28.

    Article  CAS  PubMed  Google Scholar 

  31. Foster K, Campbell D, Crum J, Stove M. Non-response in a population study after an environmental disaster. Public Health 1995;109(4):267–73.

    Article  CAS  PubMed  Google Scholar 

  32. Siemiatycki J, Campbell S. Nonresponse bias and early versus all responders in mail and telephone surveys. Am J Epidemiol 1984;120(2):291–301.

    Article  CAS  PubMed  Google Scholar 

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Authors and Affiliations

  1. Division of Nephrology, University of Western Ontario, London, Ontario, Canada

    Amit Garg MD, Jennifer Macnab PhD, William Clark MD & Rita S. Suri MD

  2. Department of Epidemiology and Biostatistics, University of Western Ontario, Canada

    Amit Garg MD & Jennifer Macnab PhD

  3. Department of Medicine, University of Toronto, Toronto, Ontario, Canada

    Joel G. Ray MD, MSc

  4. Department of Medicine, McMaster University, Hamilton, Ontario, Canada

    John K. Marshall MD, MSc, P. J. Devereaux MD & Brian Haynes MD, PhD

  5. Department of Clinical Epidemiology and Biostatistics, McMaster University, Canada

    P. J. Devereaux MD & Brian Haynes MD, PhD

  6. Kidney Clinical Research Unit, Room A01, Westminster Tower, London Health Sciences Centre, 800 Commissioners Road East, London, ON, N6A 4G5, Canada

    Amit Garg MD

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  1. Amit Garg MD
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Correspondence to Amit Garg MD.

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Garg, A., Macnab, J., Clark, W. et al. Long-term Health Sequelae Following E.coli and Campylobacter Contamination of Municipal Water. Can J Public Health 96, 125–130 (2005). https://doi.org/10.1007/BF03403675

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