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Updated: Jul 21, 2026
07:28
A Protocol of Manual Tests to Measure Sensation and Pain in Humans
Published on: December 19, 2016
The pain visual analog scale: is it linear or nonlinear?
P S Myles1, S Troedel, M Boquest
1Department of Anaesthesia and Pain Management, Alfred Hospital, Prahan, Victoria, Australia. p.myles@alfred.org.au
Anesthesia and Analgesia
|December 10, 1999
Summary
The visual analog scale (VAS) is a reliable tool for measuring pain intensity. This study confirms that VAS scores can be treated as ratio data, supporting its use in clinical trials.
Area of Science:
- Pain Management
- Psychometrics
Background:
- The visual analog scale (VAS) is frequently used for pain assessment.
- Debate exists regarding whether VAS scores represent ratio or ordinal data.
Purpose of the Study:
- To determine if the visual analog scale (VAS) yields ratio data for pain intensity.
- To validate the VAS as a quantitative measure in pain research.
Main Methods:
- 52 postoperative patients rated their pain intensity using the VAS (VAS1).
- Patients conceptually adjusted their pain perception (twice as much, half as much) and re-rated (VAS2, VAS3).
- Pain was pharmacologically managed (IV fentanyl) for further assessment of half-pain ratings.
Main Results:
- The mean ratio of VAS2 to VAS1 was 2.12 (95% CI: 1.81-2.43).
- The mean ratio of VAS3 to VAS1 was 0.45 (95% CI: 0.38-0.52).
- These findings indicate linearity in VAS scores for mild-to-moderate pain.
Conclusions:
- The visual analog scale (VAS) provides ratio data for pain intensity.
- VAS scores can be reliably used to quantify pain magnitude and compare analgesic efficacy in trials.
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