The Visual Analog Scale (VAS) is one of the four (4) pain measurement scales along side the Numerical Rating Scale (NRS), Verbal Rating Scale (VRS) and the Faces Pain Scale-Revised (FPS-R) (Ferreira-Valente, Pais-Ribeiro, & Jensen, 2011). The VAS categorizes pain and aims to simplify and measure a characteristic that cannot necessarily be directly measured.
The VAS uses a straight 10 centimeter line with one end being ‘no pain’ and on the other end the ‘worst imaginable pain’. The patient chooses a spot on the line then places a perpendicular line to indicate their pain level within the last 24 hours.
The tool was first used in 1923 by Freyd in Psychology to measure well-being then later combined with the Graphic Rating Scale (GRS). The GRS includes terms such as ‘mild’, ‘moderate’ or ‘severe’ underneath the line or a scale of 1-100 (Haefeli, Mathias, and Elfering, 2006).
How is it scored/calculated
The VAS can be taken electronically or with a pen and paper. “Electronic VAS scores showed a high correlation with the paper VAS and it was concluded that this is a valid and time-saving method for pain assessment” (Haefeli, Mathias, and Elfering, 2006). It is measured based on a scale of 0 to 100 with 0 being no pain and 100 being the worst imaginable pain. The VAS should take less than one (1) minute for patients to complete. The VAS is scored by the following measures: no pain (0–4 mm), mild pain (5-44 mm), moderate pain (45–74 mm), and severe pain (75–100 mm) (Physiopedia Contributors, 2019).
The VAS has proven to be a valid and reliable tool in order to track pain levels. “The VAS is widely used due to its simplicity and adaptability to a broad range of populations and settings. Its acceptability as a generic pain measure was demonstrated in the early 1970s” (Hawker, Mian, & others, 2011). A major advantage of this tool when compared to others, is that it is helpful when repeated at two (2) different intervals because it’s an accurate representation of differences in pain levels over time (Klimek, Bergmann, & others, 2017).
VAS is not very accurate in determining changes over a period of time unless it is retaken. This is because it inquires about a pain measure within the last 24 hours. It is also controversial because many believe that pain is not an important factor and is all psychological (Haefeli, Mathias, and Elfering, 2006). VAS may be difficult for some to understand because it’s just a line with phrases as either end. This assessment may easily cause confusion or be misinterpreted by some, especially elderly or those with whom are illiterate. This group of patients may benefit from someone aiding and assisting in the completion of the survey. There may also be high cost involved due to the effort to statistically analyze the data (Klimek, Bergmann, & others, 2017). It is highly recommended to take caution when photo-copying the scale in order to ensure consistency.
Ferreira-Valente, Pais-Ribeiro, & Jensen. (October, 2011). Validity of the four pain intensity rating scale. PubMed. Retrieved from Link
Haefeli, Mathias and Elfering, Achim. (January 15, 2006). Pain Assessment. PMC. Retrieved from Link
Hawker, Mian, & others. (November 7, 2011). Measures of adult pain: Visual Analog Scale for Pain (VAS Pain), Numeric Rating Scale for Pain (NRS Pain), McGill Pain Questionnaire (MPQ), Short‐Form McGill Pain Questionnaire (SF‐MPQ), Chronic Pain Grade Scale (CPGS), Short Form‐36 Bodily Pain Scale (SF‐36 BPS), and Measure of Intermittent and Constant Osteoarthritis Pain (ICOAP). Wiley Online Library. Retrieved from Link
Klimek, Bergmann, & others. (January 19, 2017). Visual analogue scales (VAS): Measuring instruments for the documentation of symptoms and therapy monitoring in cases of allergic rhinitis in everyday health care. PMC. Retrieved from Link
Physiopedia contributors. (April 25, 2019) Visual Analogue Scale. Physiopedia. Retrieved from Link