The influence of rater training on inter-and intra-rater reliability when using the rat grimace scale
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Abstract
Rodent grimace scales facilitate assessment of spontaneous pain and can identify a range of acute pain levels. Reported rater training in using these scales varies considerably and may contribute to observed variability in inter-rater reliability. This study evaluated the effect of training on inter-rater reliability with the Rat Grimace Scale (RGS). Two training sets, of 42 and 150 images, were prepared from several acute pain models. Four trainee raters progressed through 2 rounds of training, first scoring 42 images (S1) followed by 150 images (S2a). After each round, trainees reviewed the RGS and any problematic images with an experienced rater. The 150 images were then re-scored (S2b). Four years after training, all trainees re-scored the 150 images (S2c). Inter- and intra-rater reliability was evaluated using the intra-class correlation coefficient (ICC) and ICCs compared with a Feldt test. Inter-rater reliability increased from moderate (0.58 [95%CI: 0.43-0.72]) to very good (0.85 [0.81-0.88]) between S1 and S2b (p < 0.01) and also increased between S2a and S2b (p < 0.01). The action units with the highest and lowest ICCs at S2b were orbital tightening (0.84 [0.80-0.87]) and whiskers (0.63 [0.57-0.70]), respectively. In comparison to an experienced rater the ICCs for all trainees improved, ranging from 0.88 to 0.91 at S2b. Four years later, very good inter-rater reliability was retained (0.82 [0.76-0.84]) and intra-rater reliability was good or very good (0.78-0.87). Training improves inter-rater reliability between trainees, with an associated reduction in 95%CI. Additionally, training resulted in improved inter-rater reliability alongside an experienced rater. Performance was retained after several years. The beneficial effects of training potentially reduce data variability and improve experimental animal welfare.
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2018. The influence of rater training on inter-and intra-rater reliability when using the rat grimace scale. PeerJ Preprints 6:e26721v2 https://doi.org/10.7287/peerj.preprints.26721v2Author comment
This new version includes results from an additional analysis to evaluate intra-rater reliability 4 years after the initial training period.
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Competing Interests
The authors declare that they have no competing interests.
Author Contributions
Emily Zhang conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Vivian Leung conceived and designed the experiments, performed the experiments, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Daniel SJ Pang conceived and designed the experiments, analyzed the data, contributed reagents/materials/analysis tools, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Animal Ethics
The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):
The data used for this study was collected during previous, unrelated projects for which IACUC approval was granted.
University of Calgary Health Sciences Animal Care Committee
Data Deposition
The following information was supplied regarding data availability:
Harvard Dataverse
Rat Grimace Scale rater training data
Funding
This work was supported by a Natural Sciences and Engineering Research of Canada Discovery Grant (ID 424022-2013) and by the Fondation J.-Louis Lévesque The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
