title: Hard-to-reach populations in Japan.
abstract: The objective of this study was to assess the trends of sampling locations and methods of studying hard-to-reach populations conducted in Japan. We accessed a Japanese medical database on 30 September 2005 to review 5 study types of hard-to-reach populations conducted in Japan: men who have sex with men, homeless, sex workers, undocumented migrants, and injecting drug users. We then categorized their sampling locations and methods. We found 298 articles on hard-to-reach populations published from 1983 to September 2005. Of the 285 studies sampled, approximately 92% were facility-based studies and the rest were community-based. This tendency was consistent in each subgroup; the majority of the studies were conducted among patients in medical facilities. Our study shows the majority of studies on hard-to-reach populations in Japan adopted a convenience sampling method and were facility-based. We suggest the utilization of comparatively valid techniques, such as time-location or respondent driven sampling to more clearly understand these populations.
authors.affiliation: Department of International Community Health, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Nomura
authors.forename: Krishna C
authors.initials: KC
authors.lastname: Poudel
authors.forename: Masamine
authors.initials: M
authors.lastname: Jimba
mesh_terms: D040343:Behavioral Risk Factor Surveillance System; D015706:Bibliometrics; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000523:psychology; D006268:Health Facilities / Q000145:classification / Q000706:statistics & numerical data*; D006703:Ill-Housed Persons / Q000706:statistics & numerical data; D018451:Homosexuality, Male / Q000706:statistics & numerical data; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D012309:Risk-Taking; D011477:Sex Work / Q000706:statistics & numerical data; D015819:Substance Abuse, Intravenous / Q000453:epidemiology; D014171:Transients and Migrants / Q000706:statistics & numerical data