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Table 2 Descriptive statistics for characteristics of ALL incidence and H. pylori prevalence studies/countries

From: The association between Acute Lymphoblastic Leukemia in children and Helicobacter pylori as the marker for sanitation

ALL incidence rate (per 100,000 persons) Mean Median s.d.b Frequency (%)
Weighted ALL incidence a (28 countries) 17.61 16.40 11.75 - -
Non-weighted ALL incidence rate (127 cancer registries) 21.68 21.25 12.62 - -
Characteristics of included countries (n = 28)      
Gross National Product per capita for countries (USD$) 11375.79 9520.00 1182.10 - -
Human Development Index for countries 0.80 0.87 0.14 - -
Population size for countries 118137528 36416282 265588002 - -
Characteristics of H. pylori studies (n = 28)      
H. pylori prevalence (%) 26.56 19.30 21.46 - -
Minimum age of children (years) 2.21 1.50 2.25 - -
Maximum age of children (years) 6.21 5.00 2.43 - -
Interval between ALL incidence and H. pylori surveys (years) 4.11 3.00 4.78 - -
Method of H. pylori detection      
 Serological assays using IgG - - - 25 89.29
 Urea breath test - - - 3 10.71
Population source      
 Community-based - - - 10 35.71
 Clinic-based - - - 18 64.29
Level of urbanization      
 Rural - - - 4 14.29
 Urban - - - 16 57.14
 Both rural and urban - - - 8 28.57
Region      
 Africa - - - 2 7.14
 Americas - - - 4 14.29
 Southeast Asia - - - 2 7.14
 Europe - - - 14 50.00
 Western Pacific - - - 6 21.43
  1. a Weighted ALL incidence rate for each country was obtained using the inverse variance method.
  2. b Standard deviation.