A study conducted by Enrique Font, professor at the Cavanilles Institute of the UV, and Mathew Kramer, expert in statics of the Agriculture Department of the United States, recommends to use information of previous experiments in order to reduce the amount of animals in the control groups -those which do not receive the therapy in the experiment. The proposal, which has been published in the magazine ’Biological Reviews’, includes other suggestions such as the use of effective experimental design. This could reduce the amount of animals used in the biomedical research.
Each year, many millions of animals are slaughtered in scientific researches conducted in all the world. Almost all experiments in which these animals take part include one or more control groups. The control groups are an essential element of the experimental design but, as the authors of the work report, the majority of researchers have a very vague idea of the different types of controls and the role that they play.
In the case of experiments that are repeated on a routine basis in a laboratory, always with the same type of animal, in standard conditions and using the same experimental protocols, an effective way of reducing the size of the control groups without sacrificing the capacity of reaching valid conclusions consists of “borrowing” information of the controls used in previous experiments (historical controls).
According to Font and Kramer in the article “Reducing sample size in experiments: with animals: historical controls and related strategies”, many scientists are ignorant of the potential that the historic information can have for their researches. Through simulations and real data taken from the scientific literature, the authors of the study show that, in some circumstances, the incorporation of borrowed information of the historic controls increases the power of the statics proofs and at the same time it makes possible the decrease in the number of the animals used in the experiment.
Nevertheless, Font and Kramer point out that the use of information from previous experiments is not always possible and it should be a consistency among the historic and current conditions. ‘We recommend to use borrowed information of historic controls used in the same laboratory, by the same researchers and using identical o very similar protocols’, they advise.
The experts also deny that all experiments need controls. ‘Scientifics insist on using experimental designs in which they include control groups, even though when they are not necessary’, they affirm and attribute this to a lack of specific training about the design of experiments.
‘If a rat suffers a cross section of the spinal cord, we now that it is not going to recover spontaneously’, they say as an example. In other cases, they are necessary. Font and Kramer suggest the possibility for group controls to be smaller than the treatment groups, especially in those researches which include ‘painful or stressing procedures’.
Enrique Font Bisier is Doctor in Ethology by the University of Tennessee (Knoxville, United States). Since 1999 he is member of the Cavanilles Institute of Biodiversity and Evolutionary Biology where he directs the Research Group in Ethology. Since his incorporation into the Universitat de València, most of his research work has been focused on the study of the animal communication, field in which he has realised important contributions in recent years.
Valencia, 29 May 2017
Matthew Kramer & Enrique Font (2017) «Reducing sample size in experiments: with animals: historical controls and related strategies», Biological Reviews of the Cambridge Philosophical Society, 92, pp. 431-445, DOI: 10.1111/brv.12237