Yoshitaka Fujii

is a Japanese researcher in anesthesiology, who in 2012 was found to have fabricated data in at least 219 scientific papers, of which 183 have been retracted.

Summary of professional career

Fujii graduated from Tokai University School of Medicine in 1987 and holds an M.D. degree. He attended the Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, where he majored in anesthesiology and received his Ph.D. in 1991. During his career, he worked at institutions including Tokyo Medical and Dental University, the University of Tsukuba, and Toho University.

Research misconduct

Fujii apparently began publishing falsified data in 1993. by Peter Kranke, Christian Apfel, and others. The letter questioned Fujii's reported findings regarding the effectiveness of granisetron in controlling post-surgical nausea and vomiting, characterizing the data reported in 47 papers as "incredibly nice" and stating "we became skeptical when we realized that side effects were almost always identical in all groups". A paper published by the same group in 2001 in Acta Anaesthesiologica Scandinavica reported "consistent discrepancies" between Fujii's data and other researchers' findings on the efficacy of granisetron. Carlisle used statistical methods to evaluate whether the published distributions of various variables were consistent with the distributions that could be expected to result from random chance. He found that many of the data sets were "extremely unlikely to have arisen by chance", noting that many of the distributions had "likelihoods that are infinitesimally small", citing a calculated probability of 6.78 × 10−9, or about 1 in 150 million. Accordingly, he recommended that data published by Fujii should be "excluded from meta-analyses or reviews" until such time that the unlikely results could be satisfactorily explained. Investigators found that one of Fujii's co-authors, Hidenori Toyooka, who collaborated with Fujii on "dozens" of papers, may have been aware of the deception.

As of 2025, 172 of Fujii's research publications have been retracted. He was at the top of Retraction Watch's leaderboard until July 2023, when he was surpassed by German anesthesiologist Joachim Boldt.