Lack of interchangeability between visual analogue and verbal rating pain scales: a cross sectional description of pain etiology groups

BMC Medical Research Methodology, 2005 · DOI: 10.1186/1471-2288-5-31 · Published: October 4, 2005

Pain Management Research Methodology & Design

Simple Explanation

This study investigates whether two common pain scales, the Visual Analogue Scale (VAS) and the Verbal Rating Scale (VRS), can be used interchangeably. Researchers wanted to know if a pain score on one scale accurately reflects the same level of pain on the other scale, especially when considering different causes of pain. The study involved patients with chronic/idiopathic, nociceptive, and neuropathic pain. Participants rated their pain intensity using both the VAS (a continuous scale from 0-100) and the VRS (a five-category scale). The researchers then analyzed the data to see how well the scores on the two scales matched up within each pain group. The findings suggest that the VAS and VRS are not interchangeable. There was overlap in pain scores between the scales, meaning that a similar VAS score could correspond to different VRS categories. The cut-off points on the VAS relating to VRS categories also varied based on the cause of the pain.

Study Duration

Not specified

Participants

80 outpatients with diagnosed pain conditions (chronic/idiopathic, nociceptive, or neuropathic pain)

Evidence Level

Cross-sectional study

Key Findings

1
There was an overlapping of VAS records relative to the VRS categories in all pain groups, indicating a lack of direct correspondence between the two scales.
2
Cut-off positions for VAS records related to VRS categories were lower in patients with nociceptive pain compared to those with chronic/idiopathic and neuropathic pain, suggesting that pain etiology influences how individuals rate their pain on the VAS.
3
When VAS records were transformed into an equidistant five-category scale and compared with VRS records, systematic disagreements between the scales were observed in all groups, further highlighting the lack of interchangeability.

Research Summary

This cross-sectional study examined the interchangeability of the Visual Analogue Scale (VAS) and the Verbal Rating Scale (VRS) in assessing pain intensity among patients with chronic/idiopathic, nociceptive, and neuropathic pain. The results indicated that the VAS and VRS are not interchangeable due to overlapping pain records, systematic disagreements, and low intra-scale agreement. The meaning of rated pain intensity also appeared to differ depending on pain etiology. The authors suggest using the VRS for pain intensity assessments, but if the VAS is preferred, the data should be analyzed as continuous data. They also caution against over or underestimating a patient's perceived pain when interpreting condensed VAS data.

Practical Implications

Clinical Practice

Clinicians should be cautious when comparing pain intensity ratings obtained from VAS and VRS, as they may not be directly interchangeable.

Research Design

Researchers should carefully consider the choice of pain assessment scale and be aware of the potential for discrepancies when comparing results across studies that use different scales.

Data Analysis

When using VAS for pain assessment, data should be analyzed as continuous rather than condensed into discrete categories to avoid potential misinterpretation.

Study Limitations

1
The relatively small number of patients in the study may limit the generalizability of the findings.
2
The possible presence of various pain etiologies in some individuals could have influenced the results.
3
The results refer to rated, individual actual pain intensity of patients suffering from pain of different etiologies and cannot be generalized to other situations.

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