Helicobacter pylori Prevalences and Risk Factors among School Beginners in a German Urban Center and Its Rural County

Environmental Health Perspectives, June, 2001 by Olf Herbarth, Peter Krumbiegel, Gisela J. Fritz, Matthias Richter, Uwe Schlink, Detlef M. Muller, Thomas Richter

Results of the cluster analysis of the total population (city and county) are presented in Figure 1. The main cluster, the variables close to the target HP test (H. pylori positivity), includes the varibles with the least geometric distance from the target. These variables were entered into the multivariate logistic regression analysis to determine odds ratios and significance levels. When applied separately to the data sets (Leipzig city and Leipzig County), cluster analyses of the same 47 selected variables showed that the distance of some cluster variables to the target, H. pylori positivity, varied for the city and county, indicating differences in their importance in the association. The variable "contact with pet hamsters" was associated more closely with H. pylori positivity in the city children than in the county children. In contrast, the variables "use of human excrement as garden fertilizer" and the "drinking of water from nonmunicipal sources" appear closer linked to the target variable in the county. The odds ratios (Table 4) show that not all variables clustering close to the target are significant.

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Table 4. Significant odds ratios of risk factors for city and county
children and for the total population.

Transmission routes           OR     95% CI    p-Value

Contact with pet hamsters
  City                        2.4   1.2-4.7     0.015
  County                      2.4   1.0-5.7     0.04
  City   County               2.1   1.2-3.7     0.009
Travels to Asian countries
  City                        3.7   1.6-8.7     0.002
  Total                       3.1   1.4-6.8     0.005
Drinking water in garden
  County                     16.4   3.1-88.5    0.001
  Total                       2.8   1.0-8.3     0.05
> 3 children in household
  County                      4.2   1.2-14.6    0.02
  Total                       2.6   1.1-6.6     0.024

City odds ratios are based on 1,785 complete data sets; p = 0.003.
County odds ratios are based on 976 complete data sets; p = 0.0005.
City   County odds ratios are based on 2,727 complete data sets;
p = 0.0008.

Among city children, the models with significant associations with H. pylori positivity are "contact with pet hamsters" (OR = 2.4; 95% CI, 1.2-4.7; p [is less than] 0.015) and "travels to Asian countries" (OR = 3.7; 95% CI, 1.6-8.7; p [is less than] 0.002); among county children, there are significant associations for "drinking of water from nonmunicipal sources" (OR = 16.4; 95% CI, 3.1-88.5; p [is less than] 0.001), "more than 3 children in the household" (OR = 4.2; 95% CI, 1.2-14.6; p [is less than] 0.02) and "contact with pet hamsters" (OR = 2.4; 95% CI, 1.0-5.7; p [is less than] 0.04). The model for the entire sample population, based on 2,727 data sets, is highly significant (p = 0.0008). The variables included are "contact with pet hamsters'' (OR = 2.1; 95% CI, 1.2-3.8; p [is less than] 0.009), "travels to Asian countries" (OR=3.1; 95% CI, 1.4-6.6; p [is less than] 0.005), "drinking of water from nonmunicipal sources" (OR = 2.8; 95% CI, 1.0-8.2; p [is less than] 0.05) and "more than 3 children in the household" (OR = 2.6; 95% CI, 1.1-5.9; p [is less than] 0.024).

Although we included reported clinical symptoms in a child or a family history of recurrent abdominal pain, dyspepsia, gastric/peptic ulceration, etc. in the model to test their general and specific importance as risk factors, this analysis indicated that these host factors did not significantly contribute to the prediction of H. pylori positivity. For example, inclusion of the symptoms "recurrent abdominal pain" and "recurrent belching" into the regression model for the total population (Table 5) only weakened the association. The p-value of the model, in spite of remaining significant, increased from 0.0008 (without the clinical indicators) to 0.0028.