Table 1: Association of risk factors with H. pylori infection in different regions

						Association of risk factors with H. pylori infection		References
Country		Study population (number of subjects)		Age range (years)		Yes		No
Czech		Healthy children		0-15		•  Two or more children in the household				Sykora et al42
Republic		(1,545)		0-15
						•  Institutionalization of the child
						•  Lack of formal education of the father
Greece		Symptomatic		Mean				•  Socioeconomic status		Roma et al41
		children (100)		11.02				•  Parental educational level
								•  Number of children in the household
								•  Sharing a room or a bed with parents or siblings
Taiwan		Healthy high-school		Mean 14.3				•  Number of siblings		Chi et al40
		students (106)						•  Household size
								•  Parental educational level
								•  Family income
Pakistan		Children (1,976)		1-15		• Lower socioeconomic status		•  Water source to household		Jafri et al39
						•  Lower educational status of the child’s father		•  Tyoe of housing		Jafri et al39
Turkey		Healthy children		2-12		•  Lower family income				Yucel et al34
		(165)				•  Poor living conditions
						•  Lower educational status of the mother
						•  Higher number of siblings
Italy		Healthy children		5-16		•  Living in rural areas		•  Socioeconomic status for children in rural areas		Fujimura et al38
		(2,810)				•  Contact with dogs for children in rural areas		•  Breast-fed history for children in rural and urban areas
						•  Lower socioeconomic status for children in urban areas
						•  Attending daycare centers for children in urban areas
Sao		Healthy children		Mean 6.82				•  Gender		Miranda et al45
Paulo,		(326)						•  Race (white or nonwhite)
Brazil								•  Breast-feeding
								•  Number of people in the home
								•  Number of rooms
								•  Bed sharing
								•  Living in a shantytown
								•  Family income
								•  Nutritional status
Brazil		Healthy children		0.5-12		•  Absence of a sewage system		•  Maternal educational level		Parente et al46
		(303)				•  Absence of garbage collection service
						•  Absence of indoor plumbing
Brazil		Healthy children		Mean 6.1		•  Increased number of children in the household				Queiroz et al44
		(133)				•  Use of well water
Brazil		Healthy children		Mean 6.8		•  A larger sibling number				Dattoli et al43
		(1,104)				•  Nursery attendance
						•  Location of the house at an unpaved street
						•  Absence of a flush toilet