In the last decade the number of bioscience journals has increased enormously, with
many filling specialised niches reflecting new disciplines and technologies. The emergence
of open-access journals has revolutionised the publication process, maximising the
availability of research data. Nevertheless, a wealth of evidence shows that across
many areas, the reporting of biomedical research is often inadequate, leading to the
view that even if the science is sound, in many cases the publications themselves
are not “fit for purpose,” meaning that incomplete reporting of relevant information
effectively renders many publications of limited value as instruments to inform policy
or clinical and scientific practice –. A recent review of clinical research
showed that there is considerable cumulative waste of financial resources at all stages
of the research process, including as a result of publications that are unusable due
to poor reporting . It is unlikely that this issue is confined to clinical research
Failure to describe research methods and to report results appropriately therefore
has potential scientific, ethical, and economic implications for the entire research
process and the reputation of those involved in it. This is particularly true for
animal research, one of the most controversial areas of science. The largest and most
comprehensive review of published animal research undertaken to date, to our knowledge,
has highlighted serious omissions in the way research using animals is reported .
The survey, commissioned by the National Centre for the Replacement, Refinement and
Reduction of Animals in Research (NC3Rs), a UK Government-sponsored scientific organisation,
found that only 59% of the 271 randomly chosen articles assessed stated the hypothesis
or objective of the study, and the number and characteristics of the animals used
(i.e., species/strain, sex, and age/weight). Most of the papers surveyed did not report
using randomisation (87%) or blinding (86%) to reduce bias in animal selection and
outcome assessment. Only 70% of the publications that used statistical methods fully
described them and presented the results with a measure of precision or variability
. These findings are a cause for concern and are consistent with reviews of many
research areas, including clinical studies, published in recent years –.
Good Reporting Is Essential for Peer Review and to Inform Future Research
Scrutiny by scientific peers has long been the mainstay of “quality control” for the
publication process. The way that experiments are reported, in terms of the level
of detail of methods and the presentation of key results, is crucial to the peer review
process and, indeed, the subsequent utility and validity of the knowledge base that
is used to inform future research. The onus is therefore on the research community
to ensure that their research articles include all relevant information to allow in-depth
critique, and to avoiding duplicating studies and performing redundant experiments.
Ideally scientific publications should present sufficient information to allow a knowledgeable
reader to understand what was done, why, and how, and to assess the biological relevance
of the study and the reliability and validity of the findings. There should also be
enough information to allow the experiment to be repeated . The problem therefore
is how to ensure that all relevant information is included in research publications.
Using Reporting Guidelines Measurably Improves the Quality of Reporting
Evidence provided by reviews of published research suggests that many researchers
and peer reviewers would benefit from guidance about what information should be provided
in a research article. The CONSORT Statement for randomised controlled clinical trials
was one of the first guidelines developed in response to this need ,. Since
publication, an increasing number of leading journals have supported CONSORT as part
of their instructions to authors ,. As a result, convincing evidence is emerging
that CONSORT improves the quality and transparency of reports of clinical trials ,.
Following CONSORT, many other guidelines have been developed—there are currently more
than 90 available for reporting different types of health research, most of which
have been published in the last ten years (see http://www.equator-network.org and
references ,). Guidelines have also been developed to improve the reporting
of other specific bioscience research areas including metabolomics and gene expression
studies –. Several organisations support the case for improved reporting and
recommend the use of reporting guidelines, including the International Committee of
Medical Journal Editors, the Council of Science Editors, the Committee on Publication
Ethics, and the Nuffield Council for Bioethics –.
Improving the Reporting of Animal Experiments—The ARRIVE Guidelines
Most bioscience journals currently provide little or no guidance on what information
to report when describing animal research –. Our review found that 4% of the
271 journal articles assessed did not report the number of animals used anywhere in
the methods or the results sections . Reporting animal numbers is essential so
that the biological and statistical significance of the experimental results can be
assessed or the data reanalysed, and is also necessary if the experimental methods
are to be repeated. Improved reporting of these and other details will maximise the
availability and utility of the information gained from every animal and every experiment,
preventing unnecessary animal use in the future. To address this, we led an initiative
to produce guidelines for reporting animal research. The guidelines, referred to as
ARRIVE (Animals in Research: Reporting In Vivo Experiments), have been developed using
the CONSORT Statement as their foundation ,.
The ARRIVE guidelines consist of a checklist of 20 items describing the minimum information
that all scientific publications reporting research using animals should include,
such as the number and specific characteristics of animals used (including species,
strain, sex, and genetic background); details of housing and husbandry; and the experimental,
statistical, and analytical methods (including details of methods used to reduce bias
such as randomisation and blinding). All the items in the checklist have been included
to promote high-quality, comprehensive reporting to allow an accurate critical review
of what was done and what was found.
Consensus and consultation are the corner-stones of the guideline development process
. To maximise their utility, the ARRIVE guidelines have been prepared in consultation
with scientists, statisticians, journal editors, and research funders. We convened
an expert working group, comprising researchers and statisticians from a range of
disciplines, and journal editors from Nature Cell Biology, Science, Laboratory Animals,
and the British Journal of Pharmacology (see Acknowledgments). At a one-day meeting
in June 2009, the working group agreed the scope and broad content of a draft set
of guidelines that were then used as the basis for a wider consultation with the scientific
community, involving researchers, and grant holders and representatives of the major
bioscience funding bodies including the Medical Research Council, Wellcome Trust,
Biotechnology and Biological Sciences Research Council, and The Royal Society (see
Table 1). Feedback on the content and wording of the items was incorporated into the
final version of the checklist. Further feedback on the content utility of the guidelines
is encouraged and sought.
Funding bodies consulted.
Name of Bioscience Research Funding Body
Medical Research Council
Biotechnology and Biological Sciences Research Council
The Royal Society
Association of Medical Research Charities
British Heart Foundation
Parkinson's Disease Society
The ARRIVE guidelines (see Table 2) can be applied to any area of bioscience research
using laboratory animals, and the inherent principles apply not only to reporting
comparative experiments but also to other study designs. Laboratory animal refers
to any species of animal undergoing an experimental procedure in a research laboratory
or formal test setting. The guidelines are not intended to be mandatory or absolutely
prescriptive, nor to standardise or formalise the structure of reporting. Rather they
provide a checklist that can be used to guide authors preparing manuscripts for publication,
and by those involved in peer review for quality assurance, to ensure completeness
Animal Research: Reporting In Vivo experiments: The ARRIVE guidelines.
Provide as accurate and concise a description of the content of the article as possible.
Provide an accurate summary of the background, research objectives (including details
of the species or strain of animal used), key methods, principal findings, and conclusions
of the study.
a. Include sufficient scientific background (including relevant references to previous
work) to understand the motivation and context for the study, and explain the experimental
approach and rationale.b. Explain how and why the animal species and model being used
can address the scientific objectives and, where appropriate, the study's relevance
to human biology.
Clearly describe the primary and any secondary objectives of the study, or specific
hypotheses being tested.
Indicate the nature of the ethical review permissions, relevant licences (e.g. Animal
[Scientific Procedures] Act 1986), and national or institutional guidelines for the
care and use of animals, that cover the research.
For each experiment, give brief details of the study design, including:a. The number
of experimental and control groups.b. Any steps taken to minimise the effects of subjective
bias when allocating animals to treatment (e.g., randomisation procedure) and when
assessing results (e.g., if done, describe who was blinded and when).c. The experimental
unit (e.g. a single animal, group, or cage of animals).A time-line diagram or flow
chart can be useful to illustrate how complex study designs were carried out.
For each experiment and each experimental group, including controls, provide precise
details of all procedures carried out. For example:a. How (e.g., drug formulation
and dose, site and route of administration, anaesthesia and analgesia used [including
monitoring], surgical procedure, method of euthanasia). Provide details of any specialist
equipment used, including supplier(s).b. When (e.g., time of day).c. Where (e.g.,
home cage, laboratory, water maze).d. Why (e.g., rationale for choice of specific
anaesthetic, route of administration, drug dose used).
a. Provide details of the animals used, including species, strain, sex, developmental
stage (e.g., mean or median age plus age range), and weight (e.g., mean or median
weight plus weight range).b. Provide further relevant information such as the source
of animals, international strain nomenclature, genetic modification status (e.g. knock-out
or transgenic), genotype, health/immune status, drug- or test-naïve, previous procedures,
Housing and husbandry
Provide details of:a. Housing (e.g., type of facility, e.g., specific pathogen free
(SPF); type of cage or housing; bedding material; number of cage companions; tank
shape and material etc. for fish).b. Husbandry conditions (e.g., breeding programme,
light/dark cycle, temperature, quality of water etc. for fish, type of food, access
to food and water, environmental enrichment).c. Welfare-related assessments and interventions
that were carried out before, during, or after the experiment.
a. Specify the total number of animals used in each experiment and the number of animals
in each experimental group.b. Explain how the number of animals was decided. Provide
details of any sample size calculation used.c. Indicate the number of independent
replications of each experiment, if relevant.
Allocating animals to experimental groups
a. Give full details of how animals were allocated to experimental groups, including
randomisation or matching if done.b. Describe the order in which the animals in the
different experimental groups were treated and assessed.
Clearly define the primary and secondary experimental outcomes assessed (e.g., cell
death, molecular markers, behavioural changes).
a. Provide details of the statistical methods used for each analysis.b. Specify the
unit of analysis for each dataset (e.g. single animal, group of animals, single neuron).c. Describe
any methods used to assess whether the data met the assumptions of the statistical
For each experimental group, report relevant characteristics and health status of
animals (e.g., weight, microbiological status, and drug- or test-naïve) before treatment
or testing (this information can often be tabulated).
a. Report the number of animals in each group included in each analysis. Report absolute
numbers (e.g. 10/20, not 50%a).b. If any animals or data were not included in the
analysis, explain why.
Outcomes and estimation
Report the results for each analysis carried out, with a measure of precision (e.g.,
standard error or confidence interval).
a. Give details of all important adverse events in each experimental group.b. Describe
any modifications to the experimental protocols made to reduce adverse events.
a. Interpret the results, taking into account the study objectives and hypotheses,
current theory, and other relevant studies in the literature.b. Comment on the study
limitations including any potential sources of bias, any limitations of the animal
model, and the imprecision associated with the resultsa.c. Describe any implications
of your experimental methods or findings for the replacement, refinement, or reduction
(the 3Rs) of the use of animals in research.
Comment on whether, and how, the findings of this study are likely to translate to
other species or systems, including any relevance to human biology.
List all funding sources (including grant number) and the role of the funder(s) in
Schulz, et al. (2010) .
Improved Reporting Will Maximise the Output of Published Research
These guidelines were developed to maximise the output from research using animals
by optimising the information that is provided in publications on the design, conduct,
and analysis of the experiments. The need for such guidelines is further illustrated
by the systematic reviews of animal research that have been carried out to assess
the efficacy of various drugs and interventions in animal models ,,,–.
Well-designed and -reported animal studies are the essential building blocks from
which such a systematic review is constructed. The reviews have found that, in many
cases, reporting omissions, in addition to the limitations of the animal models used
in the individual studies assessed in the review, are a barrier to reaching any useful
conclusion about the efficacy of the drugs and interventions being compared ,.
Driving improvements in reporting research using animals will require the collective
efforts of authors, journal editors, peer reviewers, and funding bodies. There is
no single simple or rapid solution, but the ARRIVE guidelines provide a practical
resource to aid these improvements. The guidelines will be published in several leading
bioscience research journals simultaneously –, and publishers have already
endorsed the guidelines by including them in their journal Instructions to Authors
subsequent to publication. The NC3Rs will continue to work with journal editors to
extend the range of journals adopting the guidelines, and with the scientific community
to disseminate the guidelines as widely as possible (http://www.nc3rs.org.uk/ARRIVE).