Evidence for non‐random sampling in randomised, controlled trials by Yuhji Saitoh

Summary A large number of randomised trials authored by Yoshitaka Fujii have been retracted, in part as a consequence of a previous analysis finding a very low probability of random sampling. Dr Yuhji Saitoh co‐authored 34 of those trials and he was corresponding author for eight of them. We found a number of additional randomised, controlled trials that included baseline data, with Saitoh as corresponding author, that Fujii did not co‐author. We used Monte Carlo simulations to analyse the baseline data from 32 relevant trials in total as well as an outcome (muscle twitch recovery ratios) reported in several. We also compared a series of muscle twitch recovery graphs appearing in a number of Saitoh's publications. The baseline data in 14/32 randomised, controlled trials had p < 0.01, of which seven p values were < 0.001. Eight trials reported four ratios of the time for the return of muscle activity after neuromuscular blockade, the distributions of which were homogeneous: the p values for the observed Q statistics were 0.0055, 0.031, 0.016 and 0.0071. Comparison of graphs revealed multiple coincident or near‐coincident curves across a large number of publications, a finding also inconsistent with random sampling. Combining the continuous and categorical probabilities of the 32 included trials, we found a very low likelihood of random sampling: p = 1.27 × 10 −8 (1 in 100,000,000). The high probability of non‐random sampling and the repetition of lines in multiple graphs suggest that further scrutiny of Saitoh's work is warranted.