17. Interpretation/ scientific implications
It is important to interpret the results of the study in the context of the study objectives (see item 13 – Objectives). For hypothesis-testing studies, interpretations should be restricted to the primary outcome (see item 6 – Outcome measures). Exploratory results derived from additional outcomes should not be described as conclusive, as they may be underpowered and less reliable.
Discuss the findings in the context of current theory, ideally with reference to a relevant systematic review, as individual studies do not provide a complete picture. If a systematic review is not available, take care to avoid selectively citing studies that corroborate the results, or only those that report statistically significant findings [1].
Where appropriate, describe any implications of the experimental methods or research findings for improving welfare standards or reducing the number of animals used in future studies (e.g. the use of a novel approach reduced the results’ variability, thus enabling the use of smaller group sizes without losing statistical power). This may not be the primary focus of the research but reporting this information enables wider dissemination and uptake of refined techniques within the scientific community.
References
- Glasziou P, Altman DG, Bossuyt P, Boutron I, Clarke M, Julious S, Michie S, Moher D and Wager E (2014). Reducing waste from incomplete or unusable reports of biomedical research. Lancet (London, England). doi: 10.1016/s0140-6736(13)62228-x
Example 1
“This is in contrast to data provided by an ‘intra-renal IL-18 overexpression’ model (43), and may reflect an IL-18 concentration exceeding the physiologic range in the latter study.” [1]
Example 2
“The new apparatus shows potential for considerably reducing the number of animals used in memory tasks designed to detect potential amnesic properties of new drugs...approximately 43,000 animals have been used in these tasks in the past 5 years but with the application of the continual trials apparatus we estimate that this could have been reduced to 26,000…with the new paradigm the number of animals needed to obtain reliable results and maintain the statistical power of the tasks is greatly reduced.” [2]
Example 3
“In summary, our results show that IL-1Ra protects against brain injury and reduces neuroinflammation when administered peripherally to aged and comorbid animals at reperfusion or 3 hours later. These findings address concerns raised in a recent systematic review on IL-1Ra in stroke…and provide further supporting evidence for IL-1Ra as a lead candidate for the treatment of ischemic stroke.” [3]
References
- Schirmer B, Wedekind D, Glage S and Neumann D (2015). Deletion of IL-18 Expression Ameliorates Spontaneous Kidney Failure in MRLlpr Mice. PLOS ONE. doi: 10.1371/journal.pone.0140173
- Ameen-Ali KE, Eacott MJ and Easton A (2012). A new behavioural apparatus to reduce animal numbers in multiple types of spontaneous object recognition paradigms in rats. J Neurosci Methods. doi: 10.1016/j.jneumeth.2012.08.006
- Pradillo JM, Denes A, Greenhalgh AD, Boutin H, Drake C, McColl BW, Barton E, Proctor SD, Russell JC, Rothwell NJ and Allan SM (2012). Delayed Administration of Interleukin-1 Receptor Antagonist Reduces Ischemic Brain Damage and Inflammation in Comorbid Rats. Journal of Cerebral Blood Flow & Metabolism. doi: 10.1038/jcbfm.2012.101
Discussing the limitations of the work is important to place the findings in context, interpret the validity of the results, and ascribe a credibility level to its conclusions [1]. Limitations are unavoidable in scientific research, and describing them is essential to share experience, guide best practice, and aid the design of future experiments [2].
Discuss the quality of evidence presented in the study, and consider how appropriate the animal model is to the specific research question. A discussion on the rigour of the study design to isolate cause and effect (also known as internal validity [3]) should include whether potential risks of bias have been addressed [4] (see item 2 – Sample size, item 3 – Inclusion and exclusion criteria, item 4 – Randomisation and item 5 – blinding).
References
- Ioannidis JP (2007). Limitations are not properly acknowledged in the scientific literature. J. Clin. Epidemiol. doi: 10.1016/j.jclinepi.2006.09.011
- Puhan MA, Akl EA, Bryant D, Xie F, Apolone G and ter Riet G (2012). Discussing study limitations in reports of biomedical studies- the need for more transparency. Health Qual Life Outcomes. doi: 10.1186/1477-7525-10-23
- Wieschowski S, Chin WWL, Federico C, Sievers S, Kimmelman J and Strech D (2018). Preclinical efficacy studies in investigator brochures: Do they enable risk–benefit assessment? PLOS Biology. doi: 10.1371/journal.pbio.2004879
- Reichlin TS, Vogt L and Würbel H (2016). The Researchers’ View of Scientific Rigor—Survey on the Conduct and Reporting of In Vivo Research. PLoS ONE. doi: 10.1371/journal.pone.0165999
Example 1
“Although in this study we did not sample the source herds, the likelihood of these herds to be Influenza A virus (IAV) positive is high given the commonality of IAV infections in the Midwest. However, we cannot fully rule out the possibility that new gilts became infected with resident viruses after arrival to the herd. Although new gilts were placed into isolated designated areas and procedures were in place to minimize disease transmission (eg. isolation, vaccination), these areas or procedures might not have been able to fully contain infections within the designated areas.” [1]
Example 2
“Even though our data demonstrates that sustained systemic TLR9 stimulation aggravates diastolic HF in our model of gene-targeted diastolic HF, there are several limitations as to mechanistic explanations of causality, as well as extrapolations to clinical inflammatory disease states and other HF conditions. First, our pharmacological inflammatory model does not allow discrimination between effects caused by direct cardiac TLR9 stimulation to that of indirect effects mediated by systemic inflammation. Second, although several systemic inflammatory conditions have disturbances in the innate immune system as important features, and some of these again specifically encompassing distorted TLR9 signalling…sustained TLR9 stimulation does not necessarily represent a clinically relevant inflammatory condition. Finally, the cardiac myocyte SERCA2a KO model does not adequately represent the molecular basis for, or the clinical features of, diastolic HF.” [2]
References
- Diaz A, Perez A, Sreevatsan S, Davies P, Culhane M and Torremorell M (2015). Association between Influenza A Virus Infection and Pigs Subpopulations in Endemically Infected Breeding Herds. PLOS ONE. doi: 10.1371/journal.pone.0129213
- Dhondup Y, Sjaastad I, Scott H, Sandanger Ø, Zhang L, Haugstad SB, Aronsen JM, Ranheim T, Holmen SD, Alfsnes K, Ahmed MS, Attramadal H, Gullestad L, Aukrust P, Christensen G, Yndestad A and Vinge LE (2015). Sustained Toll-Like Receptor 9 Activation Promotes Systemic and Cardiac Inflammation, and Aggravates Diastolic Heart Failure in SERCA2a KO Mice. PLOS ONE. doi: 10.1371/journal.pone.0139715