The ARRIVE Essential 10

The updated Animal Research: Reporting In Vivo Experiments (ARRIVE) guidelines were published in July 2020. One of the unique features of the updated ARRIVE guidelines was the inclusion of two groups of recommendations: the Essential 10 and the recommended set. The rationale that the authors of ARRIVE 2.0 provided for the Essential 10 is they prioritize the reporting of information related to study reliability. It seems that the hope is that shortening the list of essential items might improve compliance. I see advantages in this abbreviated list because reporting guideline checklist items do include items for reasons other than reproducibility. A good example is Item 1 in the CONSORT statement and REFLECT statement, which asks authors to indicate if the study used randomization in the title or abstract. The rationale for this item is that it facilitates identification in electronic databases. This item has nothing to do with reliability or reproducibility. If focusing on items that are related to reproducibility improves compliance for those critical items, the ARRIVE 2.0 team will have made a breakthrough. Many of us thought, and still do think, that reporting guidelines would be a straightforward way to implement a solution to the poor reporting woes. However, it has become apparent that this is not the case. The ARRIVE 2.0 authors should be congratulated for seeking a solution to an issue we all face.

For editors and reviewers also have a role to play in good reporting. The ARRIVE 2.0 Essential 10 will hopefully be easier to work with than the checklist. It certainly hits the keys items that do impact reproducibility. Four of the ARRIVE 2.0 Essential 10 items supply basic facts about an experiment: the study design, experimental procedures, outcome measures, and results. The other six items contribute to the assessment of reproducibility. Notably, the ARRIVE 2.0 Essential 10, guides authors to report things that enable readers to assess the potential for systematic bias or random error as alternative explanations for the observed effect of the intervention. Several items contribute to more than one aspect of reproducibility.

Enthused as I am about the ARRIVE 2.0 Essential 10, some features take time to become used to implementing. One of the significant changes is the absence of a workflow that matches a manuscript.  Most reporting guidelines ask for information in the same sequence we would expect authors to present the information in a manuscript. A linear approach has advantages from a checkpoint perspective because one can check off items in a logical order while reading. For the Essential 10, I do not find the order straightforward. I should preface this by saying that I usually prefer to think that a manuscript’s methods section could have been written before the study began- like a protocol. The Essential 10 items seem to request a mixture of methods and results. Given how I interpret the methods and results sections, I usually expect that information about the sample size or power calculation will be in the method section. However, I would expect to read about the total number of animals used, and the exact number allocated to each group in the results because these are not really known until the experiment has started. Therefore, for Essential Item 2, which refers to Sample Size, I would have looked for Item 2a in the result section and item 2b in the methods section.

Item 2a. “Specify the exact number of experimental units allocated to each group, and the total number in each experiment. Also indicate the total number of animals used.”

Item 2b. Explain how the sample size was decided. Provide details of any a priori sample size calculation, if done.”

Another example of this mixture of methods and results in one item occurs for Item 3. Inclusion and exclusion criteria. I would usually look for information in Item 3a in the methods, but Item 3b in the results.

Item 3a. Describe any criteria used for including or excluding animals (or experimental units) during the experiment, and data points during the analysis. Specify if these criteria were established a priori. If no criteria were set, state this explicitly.

Item 3b: For each experimental group, report any animals, experimental units, or data points not included in the analysis and explain why. If there were no exclusions, state so.

This mixture of items will take me some time to get used to, and I anticipate reteaching some authors and reviewers how to use the tool.

Another item I will teach differently for this guideline versus others is “inclusion and exclusion criteria.” Until I read the details provided in the explanation, I assumed that the Item “Inclusion and exclusion” criteria referred to the eligible population at the beginning of the study. However, in the Essential 10, this item relates to losses during the study, i.e., after enrolment. A closer evaluation revealed that the source of my confusion was the similarity in the terms “exclusion criteria” and “eligibility criteria”. The CONSORT Statement Item 5 refers to “Eligibility criteria for participants,” and Item 3 of the REFLECT Statement also refers to the “Eligibility criteria for owner/managers and study units at each level of the organizational structure, ….”. Eligibility criteria are now apparently included in Item 8. “Animal characteristics” of the ARRIVE 2.0 Essential 10. I suspect some authors and reviewers might, like me, fail to recognize the difference, which might mean this item will need closer scrutiny to check it was interpreted correctly. As an aside, Box 3 seems like guidance for a sample size calculation rather than guidance for a power calculation. For the approach described, the sample size is the variable outcome calculated and the power chosen.

Overall, I hope the ARRIVE 2.0 Essential 10 is a more straightforward tool to implement for authors, reviewers, and editors. The items included are focused on reproducibility and helping authors focus on these features is essential. This shorter list is easy to work with, although it is also different to work with.

What do you think of the Arrive format with essential 10 and others, Contact me if you want to discuss more