Study design, statistical method, and level of evidence in Japanese and American clinical journals

Tsuguya Fukui, Mahbubur Rahman, Miho Sekimoto, Kenji Hira, Kenji Maeda, Takeshi Morimoto, Masashi Goto, Hidehiko Suzuki, Takuro Shimbo

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Clinical articles published in Japanese journals are said to be characterized by poor study design, less sophisticated statistics, and producing few high-grade clinical evidences. Two American and two Japanese medical journals, published in 1990, 1993, 1996, and 1999 were compared to find out the differences regarding study design, statistical methods, and level of clinical evidence of original articles and synthetic studies. There were 1689 original articles in American and 308 in Japanese journals. Regarding study design, American articles contributed much more to randomized controlled trials/controlled trials/clinical trials (27.9% vs. 14.3%, p=0.001), cohort studies (21.6% vs. 6.2%, p=0.001), and case-control studies (6.5% vs. 0.3%, p=0.000). Among original articles in American and Japanese journals, mean number of statistical methods used were 2.4 and 1.7 per article (p=0.000), respectively. Articles providing high grade clinical evidence (grade Ia, Ib & IIa) were much greater in proportion in American journals than Japanese journals (31.1% vs. 12.7%, p=0.001). The overall picture of Japanese medical articles seems to be improving recently, at least in terms of statistical methods toward more diversified and sophisticated way of use, compared to the previous data.

Original languageEnglish (US)
Pages (from-to)266-270
Number of pages5
JournalJournal of Epidemiology
Issue number3
StatePublished - May 2002
Externally publishedYes


  • Japan
  • Medical journals
  • Statistical procedures
  • Study design
  • USA

ASJC Scopus subject areas

  • Epidemiology


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