Aims and objectives.  This review aims to explore the research available relating to three commonly used pain rating scales, the Visual Analogue Scale, the Verbal Rating Scale and the Numerical Rating Scale. The review provides information needed to understand the main properties of the scales.

Background.  Data generated from pain-rating scales can be easily misunderstood. This review can help clinicians to understand the main features of these tools and thus use them effectively.

Method.  A MedLine review via PubMed was carried out with no restriction of age of papers retrieved. Papers were examined for methodological soundness before being included. The search terms initially included pain rating scales, pain measurement, Visual Analogue Scale, VAS, Verbal Rating Scale, VRS, Numerical/numeric Rating Scale, NRS. The reference lists of retrieved articles were used to generate more papers and search terms. Only English Language papers were examined.

Conclusions.  All three pain-rating scales are valid, reliable and appropriate for use in clinical practice, although the Visual Analogue Scale has more practical difficulties than the Verbal Rating Scale or the Numerical Rating Scale. For general purposes the Numerical Rating Scale has good sensitivity and generates data that can be statistically analysed for audit purposes. Patients who seek a sensitive pain-rating scale would probably choose this one. For simplicity patients prefer the Verbal Rating Scale, but it lacks sensitivity and the data it produces can be misunderstood.

Relevance to clinical practice.  In order to use pain-rating scales well clinicians need to appreciate the potential for error within the tools, and the potential they have to provide the required information. Interpretation of the data from a pain-rating scale is not as straightforward as it might first appear.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2702.2005.01121.x

Pain: a review of three commonly used pain rating scales.

Various types of visual analogue scales (VAS) are used in epidemiologic and clinical research. This paper reports on a randomized controlled trial to investigate the effects of variations in the orientation and type of scale on bias and precision in cross-sectional and longitudinal analyses. This trial was included in the pilot study of the SU.VI.MAX (supplementation by antioxidant vitamins and minerals) prevention trial in France in 1994. Six types of VAS (simple, middle-marked, graphic rating, graduated, graduated-numbered, and numerical rating) and two orientations (horizontal and vertical) were used to measure three symptoms of ear, nose, and throat infection at 2-month intervals in 870 subjects. Differences between scales were analyzed by comparing variances (Levene's test) and means (variance-covariance analysis for repeated measures). Scale characteristics were shown to influence the proportion of zero and low values (i.e., there was a floor effect), but not mean scores. The precision of measurements varied cross-sectionally according to the type of scale, but no differences were observed in the precision of measurement of change over time. In conclusion, the characteristics of VAS seem to be important in cross-sectional studies, particularly when symptoms of low or high intensity are being measured. Researchers should try to reach a consensus on what type of VAS to use if studies are to be compared.

/pdf/bias-and-precision-in-visual-analogue-scales-a-randomized-4b43f1zias.pdf

Bias and Precision in Visual Analogue Scales: A Randomized Controlled Trial

Oral splints are widely used in the treatment of myofascial pain of masticatory muscles, even though their mechanism of action is unknown. The present study evaluated the therapeutic efficacy of splints using a parallel, randomized, controlled and blind design. Following a sample size estimation, 63 subjects were recruited and assigned to 3 groups: (1) passive control: full occlusal splint worn only 30 min at each appointment; (2) active control: palatal splint worn 24 h/day; and (3) treatment: full occlusal splint worn 24 h/day. On each of 7 visits over 10 weeks, subjects rated on 100 mm visual analogue scales their pain intensity and unpleasantness at rest and after experimental mastication. The effect of pain on the quality of life was also rated on category scales. All pain ratings decreased significantly with time, and quality of life improved for all 3 groups. However, there were no significant differences between groups in any of the variables. These data suggest that the gradual reduction in the intensity and unpleasantness of myofascial pain, as well as the improvement of quality of life during the trial, was non-specific and not related to the type of treatment.

The efficacy of oral splints in the treatment of myofascial pain of the jaw muscles: a controlled clinical trial

Although the multidimensional nature of pain is now well recognized, there are, nevertheless, very few quantitative tests to measure the separate dimensions of pain and little data concerning their relative sensitivity. The present study compares 2 currently available methods, verbal descriptor and visual analogue scales. Eight subjects rated painful and near-painful heat stimuli by using visual analogue scales for intensity or unpleasantness and by choosing the most appropriate phrases from lists of intensity or unpleasantness descriptors. In the intensity dimension, the relationship between perception and stimulus temperature was essentially identical whether calculated from the visual analogue or verbal descriptor scales. However, data derived from the verbal descriptor scales revealed that subjects rated the painful temperatures as relatively more intense than unpleasant; this difference could not be detected using the visual analogue scales. These results confirm that both visual analogue and verbal descriptor techniques successfully quantify sensory intensity and affective aspects of pain, but that verbal descriptors may provide the more sensitive tool for separating intensity and unpleasantness.

Comparison of verbal and visual analogue scales for measuring the intensity and unpleasantness of experimental pain

We asked 78 chronic low back pain patients to report on their usual pain intensity, and on the lifestyle changes caused by their pain, on a horizontally-oriented visual analogue scale (VAS). Also, the usual and the current pain intensities were examined on a vertical VAS. Statistical analysis showed normal distribution of data in the measurement of usual pain on the horizontal VAS, but no homogeneous distribution on the vertical VAS. Therefore, in the measurement of chronic low back pain VAS should be used horizontally rather than vertically, because of higher sensitivity. The intensity of usual pain was significantly correlated with the degree of lifestyle change. No correlation was found between current and usual pain. There was no significant difference in the failure rate between the vertical and horizontal VAS. Also, there was no reduction of the failure rate by giving additional oral explanations in the use of the scale to the patient. Owing to a negative influence in distribution of rates and an increase in the failure rate, complex questions should be avoided. A short written introduction to the scale is sufficient, and oral explanations are not essential.

Chronic low back pain measurement with visual analogue scales in different settings

The linear analogue score can be used in Chinese patients with relative accuracy provided it has been well explained. The error from employing a vertical presentation is significantly less than that from a horizontal one. The choice of upward or downward orientation is a matter of convenience. Younger patients and those with higher intelligence are quicker to understand the concept and can make better judgement in placing a mark where they wish it to be. A linear analogue scale seems to be a suitable method to record and study pain in a Chinese population.

Collett B

Papers

Evaluation of the use of visual analogue scale in Chinese patients.