. 2017 Jul 31;7(7):e015855. doi: 10.1136/bmjopen-2017-015855

Table 1.

Studies on the number of Helicobacter pylori-infected individuals and prevalence rate of infection

First author	No of subjects	Population	Study design	Observation year
Asaka²⁷	426	Asymptomatic children, students and adults (participating at the health screening centre) living in Sapporo, Hokkaido	Observational study	1990
Fujisawa³¹	349	Healthy persons living in seven prefectures in the central part of Japan	Observational study	1974
	324			1984
	342			1994
Watabe³²	6 983	Participants in a mass health appraisal programme	Observational study	1996
Ueda³³	14 716	Individuals who underwent a health check-up in seven prefectures (Hokkaido, Aomori, Yamagata, Gunma, Aichi, Shiga and Kagawa)	Observational study	2005
Shiota³⁴	5 550	Patients of Oita University Hospital, Oita, Japan	Observational study	2009