Table 1.
Inter-rater reliability with the Rat Grimace Scale.
Figure 1.
Receiver operating characteristics (ROC) curve.
The optimal analgesic intervention score was >0.67, derived from a balance between the greatest values of sensitivity (84.6% [71.9–93.1]) and specificity (88.6% [73.3–96.8]. There was a significant difference in the area (0.94 [0.87–0.98], p<0.0001) under the calculated ROC curve compared with an AUC of 0.5 (representative of a non-discriminative test). n = 87 images
Figure 2.
Scatter plot of Rat Grimace Scale scores categorised by “no pain” (0) and “pain” (1) assignment.
Images of rat faces were scored by expert raters and classified as “pain” or “no pain” based on subjective evaluation. The dashed horizontal line shows the analgesic intervention score of 0.68. There is clear overlap between the two assigned pain states, reflective of the balance in sensitivity and specificity. n = 87 images
Table 2.
Potential analgesic intervention scores with associated sensitivity and specificity values.
Figure 3.
Sham treatment group and the Rat Grimace Scale.
A significant overall effect of time was observed (p = 0.02) but differences between individual time points and baseline (time 0) were not significant. All RGS scores were below the analgesic intervention score of >0.67. Dashed horizontal line is set at RGS of 0.68. n = 9. Data are mean ± SEM.
Figure 4.
Time course of Rat Grimace Scale (RGS) scores.
Pooled data (all treatment groups) show the expected increase in RGS post-operatively, followed by a decline at the 12 hour time point. [16] n = 16. Data are mean ± SEM.