title: Where Have All the Rodents Gone? The Effects of Attrition in Experimental Research on Cancer and Stroke.
abstract: Given small sample sizes, loss of animals in preclinical experiments can dramatically alter results. However, effects of attrition on distortion of results are unknown. We used a simulation study to analyze the effects of random and biased attrition. As expected, random loss of samples decreased statistical power, but biased removal, including that of outliers, dramatically increased probability of false positive results. Next, we performed a meta-analysis of animal reporting and attrition in stroke and cancer. Most papers did not adequately report attrition, and extrapolating from the results of the simulation data, we suggest that their effect sizes were likely overestimated.
authors.affiliation: Medical Neurosciences Program, Charité Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Constance
authors.initials: C
authors.lastname: Holman
authors.affiliation: NeuroCure Clinical Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany.|Center for Stroke Research, Charité Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Sophie K
authors.initials: SK
authors.lastname: Piper
authors.affiliation: Center for Stroke Research, Charité Universitätsmedizin Berlin, Berlin, Germany.|Department for Biostatistics and Clinical Epidemiology, Charité Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Grittner
authors.affiliation: Medical Neurosciences Program, Charité Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Andreas Antonios
authors.initials: AA
authors.lastname: Diamantaras
authors.affiliation: Biomedical Ethics Unit, McGill University, Montréal, Canada.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Kimmelman
authors.affiliation: Center for Stroke Research, Charité Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Bob
authors.initials: B
authors.lastname: Siegerink
authors.affiliation: NeuroCure Clinical Research Center, Charité Universitätsmedizin Berlin, Berlin, Germany.|Center for Stroke Research, Charité Universitätsmedizin Berlin, Berlin, Germany.|Department of Experimental Neurology, Charité Universitätsmedizin Berlin, Berlin, Germany.|German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.|Berlin Institute of Health, Berlin, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Dirnagl
mesh_terms: D032761:Animal Experimentation; D000818:Animals; D003198:Computer Simulation; D009369:Neoplasms; D012377:Rodentia; D018401:Sample Size; D020521:Stroke