Visual Analog Scale (VAS) for Pain

The Visual Analog Scale (VAS) is a simple clinical tool used to measure a person’s perceived pain intensity. The patient marks a point on a horizontal line that best represents their current level of pain.

Note: This on-screen version uses a 400-pixel line. This approximates the appearance of a traditional 10-cm VAS on many laptop screens, but it should not be treated as a physically exact 10-cm measurement unless the display has been calibrated.

Administration

The VAS is usually completed by the patient. In some settings, it may also be used to collect an opinion from a health professional. The patient is asked to place a mark on the line at the point that best represents their perception of their current pain state.

The VAS score is determined by measuring the distance from the left-hand end of the line to the patient’s mark. On a traditional 10-cm paper scale, this distance is usually measured in millimetres.

Recall Period

The recall period can vary depending on the purpose of the assessment. Most commonly, patients are asked to rate either their current pain intensity or their pain intensity during the last 24 hours.

Scoring and Interpretation

On a traditional 10-cm VAS, the score is calculated by measuring the distance in millimetres between the “no pain” anchor and the patient’s mark. This produces a score from 0 to 100. A higher score indicates greater pain intensity.

VAS Score	Suggested Interpretation
0–4 mm	No pain
5–44 mm	Mild pain
45–74 mm	Moderate pain
75–100 mm	Severe pain

A recent paper-based recommendation described a horizontal black line with flat endpoints and numerical anchors of 0 and 10. For digital use, the line should be presented consistently across repeat administrations whenever possible.

Merits

The VAS is widely used because it is simple, adaptable, and easy to incorporate into routine care.

• It is more sensitive to small changes than simple descriptive ordinal scales.
• It is especially useful for tracking change within the same individual over time.
• It usually takes less than one minute to complete.
• It is easy to use during routine treatment.
• It requires minimal training beyond understanding how to mark and score the line.
• It has limited language demands compared with more complex questionnaires.
• VAS data are commonly treated as interval-level data for clinical and research purposes.

Limitations and Cautions

• Pain is subjective, so interpretation should consider the broader clinical context.
• The VAS may be less useful when comparing different individuals at a single point in time.
• Some patients may have difficulty understanding or completing the scale, particularly older adults with cognitive impairment.
• The VAS cannot be administered verbally or by telephone because the patient must see the scale.
• Photocopying or resizing a paper version may change the scale length and affect scoring.
• The same scale orientation and format should be used consistently when monitoring the same patient over time.

Availability

The pain VAS is available in the public domain at no cost.

Psychometric Information

Development

The pain VAS originated from continuous visual analog scales developed in psychology to measure subjective states such as well-being. Early clinical use of the VAS for pain included descriptor extremes such as “no pain at all” and “my pain is as bad as it could possibly be.” Since then, different pain anchors have been used across clinical and research settings.

Acceptability

The VAS requires little training to administer and score and has generally been found to be acceptable to patients. Supervision may help reduce errors when patients have difficulty understanding the scale.

Reliability

Test–retest reliability has generally been reported as good. Reliability may vary depending on literacy, population, condition, and administration method. Studies have reported high reliability in acute abdominal pain, chronic musculoskeletal pain, and osteoarthritic knee pain.

In osteoarthritic knee pain, one study reported excellent test–retest reliability, with an intraclass correlation coefficient of 0.97. The reported standard error of measurement was 0.03 and the minimum detectable change was 0.08.

Validity

Because pain does not have a true gold standard measure, criterion validity is difficult to establish. Construct validity has been supported by correlations between VAS scores and other pain-rating methods, including verbal descriptive scales and numeric rating scales.

Horizontal and vertical VAS formats have also been shown to be highly correlated, although the same orientation should be used consistently for repeat testing.

Ability to Detect Change

The VAS has demonstrated sensitivity to changes in pain over time, including after analgesic therapy and nonoperative treatment. In rheumatoid arthritis, the minimal clinically significant change has been estimated at approximately 11 points on a 100-point scale. In rotator cuff disease, a minimum clinically important difference of 1.37 cm has been reported for a 10-cm pain VAS after six weeks of nonoperative care.

Digital Use Note

For digital clinical use, it is often more practical to record the patient’s response as a percentage or 0–100 score rather than assuming that the on-screen line is physically exactly 10 cm. A 400-pixel line gives a reasonable visual approximation on many laptop screens, but screen size, browser zoom, and display scaling can all affect the physical length shown to the patient.