A Comparison of Pain Rating Scales by Sampling From Clinical Trial Data

TLDR

The study aims to examine agreement and estimate sensitivity differences among pain assessment scales. The authors compared a four‑category verbal rating scale, an 11‑point numeric rating scale, and a 100‑mm visual analog scale in acute post‑oral‑surgery pain, using simulation sampling from true observation pairs to assess sensitivity. Results showed that the VAS was more powerful than the VRS‑4, while VAS and NRS‑11 had comparable sensitivity, indicating that choice between VAS and NRS‑11 can be based on preference.

Abstract

Objective: The goals of this study were to examine agreement and estimate differences in sensitivity between pain assessment scales. Design: Multiple 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. Results: There 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. Conclusions: In 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.