Visual Analogue Scale
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Introduction[edit | edit source]
A Visual Analogue Scale (VAS) is a measurement instrument that tries to measure a characteristic or attitude that is believed to range across a continuum of values and cannot easily be directly measured[1]. It is often used in epidemiologic and clinical research to measure the intensity or frequency of various symptoms.Cite error: Invalid <ref> tag; name cannot be a simple integer. Use a descriptive title For example, the amount of pain that a patient feels ranges across a continuum from none to an extreme amount of pain.[1] From the patient's perspective this spectrum appears continuous ± their pain does not take discrete jumps, as a categorization of none, mild, moderate and severe would suggest. It was to capture this idea of an underlying continuum that the VAS was devised.[1]
Purpose[edit | edit source]
The pain VAS is a unidimensional measure of pain intensity, which has been widely used in diverse adult populations, including those with rheumatic diseases.[2] [3] [4] [5] [6]
Structure,Orientation and Response Options[edit | edit source]
VAS can be presented in a number of ways,including:
- scales with a middle point,graduations or numbers (numerical rating scales),
- meter-shaped scales (curvilinear analogue scales),
- "box-scales,"scales consisting of circles equidistant from each other(one of which the subject has to mark),and
- scales with descriptive terms at intervals along a line (graphic rating scales or Likert scales) Cite error: Invalid
<ref>tag; name cannot be a simple integer. Use a descriptive title - The most simple VAS is a straight horizontal line of fixed length, usually 100 mm. The ends are defined as the extreme limits of the parameter to be measured (symptom,pain,health)Cite error: Invalid
<ref>tag; name cannot be a simple integer. Use a descriptive title orientated from the left (worst) to the right (best). In some studies,horizontal scales are orientated from right to left ,and many investigators use vertical VASCite error: Invalid<ref>tag; name cannot be a simple integer. Use a descriptive title. - No difference between horizontal and vertical VAS has been shown in a survey involving 100 subjectsCite error: Invalid
<ref>tag; name cannot be a simple integer. Use a descriptive title but other authors have suggested that the two orientations differ with regard to the number of possible angles of viewCite error: Invalid<ref>tag; name cannot be a simple integer. Use a descriptive title. Reproducibility has been shown to vary along a vertical 100-mm VAS and along a horizontal VAS Cite error: Invalid<ref>tag; name cannot be a simple integer. Use a descriptive title. The choice of terms to define the anchors of a scale has also been described as important.Cite error: Invalid<ref>tag; name cannot be a simple integer. Use a descriptive title
Administration[edit | edit source]
- They are generally completed by patients themselves but are sometimes used to elicit opinions from health professionals.
- The patient marks on the line the point that they feel represents their perception of their current state.
- The VAS score is determined by measuring in millimetres from the left hand end of the line to the point that the patient marks.[1]
Recall Period for items[edit | edit source]
Recall period for items.Varies, but most commonly respondents are asked to report “current” pain intensity or pain intensity “in the last 24 hours.”
Scoring and Interpretation[edit | edit source]
Using a ruler, the score is determined by mea-suring the distance (mm) on the 10-cm line between the “no pain” anchor and the patient’s mark, providing a range of scores from 0–100. A higher score indicates greater
pain intensity. Based on the distribution of pain VAS scores in post- surgical patients (knee replacement, hyster-ectomy, or laparoscopic myomectomy) who described their postoperative pain intensity as none, mild, moderate, or severe, 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), and severe pain (75–
100 mm) (11). Normative values are not available.
Merits and Demerits[edit | edit source]
- VAS is more sensitive to small changes than are simple descriptive ordinal scales in which symptoms are rated,for example, as mild or slight,moderate,or severe to agonizing.
- These scales are of most value when looking at change within individuals
- The VAS takes�1 minute to complete
- No training is required other than the ability to use a ruler to measure distance to determine a score
- However, assessment is clearly highly subjective
- Are of less value for comparing across a group of individuals at one time point.
- It could be argued that a VAS is trying to produce interval/ratio data out of subjective values that are at best ordinal.
- The VAS is administered as a paper and pencil measure. As a result, it cannot be admin-istered verbally or by phone.
- Caution is required when photo-copying the scale as this may change the length of the 10-cm line
Thus, some caution is required in handling such data. [1]
Obtaining the scale[edit | edit source]
The pain VAS is available in the public domain at no cost. Graphic formats for the VAS may be obtained from Scott & Huskisson or online: http:// www.amda.com/tools/library/whitepapers/hospiceinltc/ appendix-a.pdf.
References[edit | edit source]
- ↑ 1.0 1.1 1.2 1.3 1.4 D. Gould et al. Visual Analogue Scale (VAS). Journal of Clinical Nursing 2001; 10:697-706
- ↑ Mc Cormack HM, Horne DJ, Sheather S. Clinical applications of visual analogue scales: a critical review. Psychol Med 1988;18:1007–19.
- ↑ Huskisson EC. Measurement of pain. Lancet 1974;2:1127–31.
- ↑ Downie WW, Leatham PA, Rhind VM, Wright V, Branco JA, Anderson JA. Studies with pain rating scales. Ann Rheum Dis 1978;37:378–81.
- ↑ Huskisson EC, Wojtulewski JA, Berry H, Scott J, Hart FD, Balme HW. Treatment of rheumatoid arthritis with fenoprofen: comparison with aspirin. Br Med J 1974;1:176–80.
- ↑ Berry H, Huskisson EC. Treatment of rheumatoid arthritis. Clin Trials J 1972;4:13–5
