Last Updated on October 30, 2023
The visual analog scale [VAS] is a measure of pain intensity. It is a continuous scale comprised of a horizontal (called horizontal visual analog scale) or, vertical called vertical visual analog scale usually 10 cm or 100 mm in length [both 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 the 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 the classic visual analog scale 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.
Another visual analog scale
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)
The significance of the Visual Analog Scale
Pain visual analog scale is very easy to use by respondent and assessor both. Woodford and Merskey first reported the 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
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.
Color visual analog scale or color analog scale is a pain assessment tool that is built on the pattern of Visual Analog Scale.
The color analog scale is used in children and in patients with poor cognition such as Alzheimer disease.
What is Color Analog Scale?
Color analog scale is 10 cm in length. It is 20 mm wide at the bottom and white in color [see image].
The white color indicates no pain.
The scale further widens to 75 mm at the top and gradually changes in color to red. The top red color indicates the worst pain.
The reverse side of the scale is numbered from 0 to 10 in 1-cm increments, enabling investigators to quantify the children’s responses.
How To Use?
The respondent is told something like following in his/ her language
“See this scale, it is like a thermometer. The bottom, where it is small and white means no pain and the top where it is wider and red means the most pain you can imagine” and the assessor points to each end while describing.
After explaining about the scale, the respondent is asked to do his/her part
“You slide the marker to the spot on the thermometer that shows how much pain you are having right now.
All measurements are recorded to the closest 0.25 cm.
Validity
Repeated studies have shown color analog scale to be a valid scale for the evaluation of pain intensity in children.
