• E K Breivik, G A Björnsson, and E Skovlund.
• Department of Oral Surgery and Oral Medicine, University of Oslo, Norway. ekristin@udont.uio.no
• Clin J Pain. 2000 Mar 1; 16 (1): 22-8.

ObjectiveThe goals of this study were to examine agreement and estimate differences in sensitivity between pain assessment scales.DesignMultiple simultaneous pain assessments by patients in acute pain after oral surgery were used to compare a four-category verbal rating scale (VRS-4) and an 11-point numeric rating scale (NRS-11) with a 100-mm visual analog scale (VAS). The sensitivity of the scales (i.e., their ability [power] to detect differences between treatments) was compared in a simulation model by sampling from true pairs of observations using varying treatment differences of predetermined size.ResultsThere was considerable variability in VAS scores within each VRS-4 or NRS-11 category both between patients and for repeated measures from the same patient. Simulation experiments showed that the VAS was systematically more powerful than the VRS-4 in all simulations performed. The sensitivity of the VAS and NRS-11 was approximately equal.ConclusionsIn this acute pain model, the VRS-4 was less sensitive than the VAS. The simulation results demonstrated similar sensitivity of the NRS-11 and VAS when comparing acute postoperative pain intensity. The choice between the VAS and NRS-11 can thus be based on subjective preferences.

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