Table 3 Summary of key evidence to support the visual analog scale (VAS) in pain

Skovlund et al. 2005 [22]

Cross-sectional study, Direct, A

The VAS is consistently more sensitive than the four-point VRS.

Chan et al. 2005 [43]

Prospective study, Direct, C

The VAS as a numeric measure of pain intensity allowed for documentation of pain over time and assessment of the relationship between pain and disability and function post-hand injury.

Loos et al. 2008 [24]

Cross-sectional study, Direct, A

Because of lower scale failure rates and overlapping VAS scores per VRS category, the VRS should be favored over the VAS in future post-herniorrhaphy pain assessment.

Boomershine et al. 2011 [44]

Prospective study, Direct, C

The VAS is simple to score for longer instruments and has been shown here to be valid, sensitive to change, and able to identify with score cut offs patients with clinically significant symptoms.

Bergh et al. 2011 [45]

Clinical study, Direct, A

The VAS is more sensitive than the Pain Matchers (PM) for recording changes in pain intensity when assessing the effects of treatment on labor pain.

Dogan et al. 2012 [23]

Prospective study, Direct, A

No patients had difficulty completing either pain scale (VAS versus Faces scale) (there were illiterate patients in the sample).

Gonzalez-Fernandez et al. 2014 [15]

Cross-sectional study, Direct, A

The VAS (with some intermediate verbal anchors) has the potential to replace the VAS in the measurement of pain intensity in the clinical setting.