Visual analog scale [VAS] is a measure of pain intensity. It is a continuous scale comprised of a horizontal (called horizontal visual analogue scale) or,vertical called vertical visual analog scale usually 10 cm or 100 mm length [both the gradations are used]. It is anchored by two verbal descriptors, one for each symptom extreme.
There could be variation in verbal descriptor anchors depending on intended use of the scale.
For pain intensity, the scale is most commonly anchored by “no pain” (score of 0) and “pain as bad as it could be” or “worst imaginable pain” (score of 100 [on 100-mm scale]
Though some scales use them, numbers or verbal descriptors at intermediate points are not recommended. This is done to avoid clustering.
Here is an image of classic VAS I have just described.
Usually, respondents are asked to report current pain intensity or pain intensity in the last 24 hours.
Here is another variation of the scale used. This looks more descriptive and seems user friendly than one pictured above.
How To Use Visual Analog Scale
The pain visual analog scale is self completed by the respondent. The respondent is asked to place a line perpendicular to the VAS line at the point that represents their pain intensity.
After the patient has marked, using a ruler, the score is determined by measuring the distance (mm) on the 10-cm line between the “no pain” anchor and the patient’s mark.
The scores can be from 0–100.
A higher score indicates greater pain intensity.
Based on the distribution of pain VAS scores in postsurgical patients, the following cut points on the pain VAS have been recommended
- No pain (0 –4 mm)
- Mild pain (5–44 mm)
- Moderate pain (45–74 mm)
- Severe pain (75–100 mm)
Significance of Visual Analog Scale
Pain visual analog scale is very easy to use by respondent and assessor both. Woodforde and Merskey first reported use of the VAS pain scale. The reliability of the test has shown to be good and is higher among literate
VAS has been shown to be highly correlated with a 5-point verbal descriptive scale [ mild to severe]
Limitations to the use of the pain VAS include the following
- older patients may have dif?culty completing the pain VAS due to cognitive impairments or motor skill issues.
- It cannot be administered by telephone, limiting its usefulness in research.
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