Visual Analog Scales and Pain Assessment: Introduction

Pain assessment is the key to the effective treatment of both acute and chronic pain. Pain is a multifaceted phenomenon; a mixture of sensory, emotional and cultural experiences. As pain is a complex internal event, self-reports are becoming valuable tools in research and practice. The visual analog scale (VAS), in particular, is one of the most popular subjective measurements used in the effective assessment and treatment of pain intensity.

The visual analog scale, also known as the graphic rating scale is a simple, valid and reliable subjective measure. Interestingly, the scale was used for the first time in 1921, by Hayes and Patterson. The visual analog scale allows patients to assess their pain experiences with high precision. Scores are ranked on a 10-cm line that stretches between two extremes – “no pain” and “worst pain” (Delgado et al., 2018). Note that this scale can be represented as a horizontal or a vertical line. Moreover, the visual analog scale is a versatile continuous scale which can be applied to a wide range of clinical settings, such as labor pain, neuropathic pain, fatigue in chronic pain, and patients’ quality of life.

Numerical Rating Scales
Verbal Rating Scales
Emojination

Benefits and Limitations of Visual Analog Scales

The visual analog scale reveals numerous benefits in medical research and routine clinical care (Kliger et al., 2015). Some of its major strengths are:

  • High sensitivity: One of the main advantages of the visual analog scale over other pain assessments is its high sensitivity. As the scale represents a 100-mm line, patients’ options are not limited to a few verbal descriptors or numbers.
  • Applicable across a wide variety of populations: The lack of verbal descriptors and scores allows subjects with low reading and numerical skills to complete the assessment. Patients have to choose a marker that fits their pain experience and opt for effective pain treatment.
  • Easy to administer and analyze: Visual analog scales are easy and quick to administer. Such tools benefit the reassessment of pain and the comparison of pain experiences between patients, which can improve pain treatment and care.

That said, the visual analog scale has a few limitations. One of the disadvantages of the visual analog scale is the need for clear vision. Research shows the scale can be challenging for 7%-16% of patients who are unable to convert pain experience to an abstract line (e.g., children and mentally challenged patients). In addition, researchers disapprove of the inability to administer the scale remotely (e.g., telephone-based assessments or interactive voice response). Yet, the visual analog scale is one of the most powerful pain assessments used in practice.

Psychometric Properties of Visual Analog Scales

The selection of an appropriate subjective measurement in research and clinical care is paramount, and it’s often based on the psychometric properties of the scale of interest. The visual analog scale, in particular, reveals good psychometric properties, such as validity, reliability, and sensitivity. In fact, research shows that the scale is more sensitive than a four-point verbal rating scale and equally well-accepted as a faces rating scale. The visual analog scale is simple to complete and analyze; it’s also able to identify cut-off scores of patients with clinically significant symptoms (Safikhani et al., 2018).

Interestingly, some researchers suggest that the visual analog scale and the numeric rating scale can be used interchangeably. Nevertheless, Kliger and colleagues conducted a retrospective study, involving 796 patients with chronic pain, and concluded that the two scales could not be defined as interchangeable (Kliger et al., 2015). Despite the high Spearman correlations between the visual analog scale and the verbal rating scale, each measurement has its specific benefits and applications. The interpretation of any subjective scale is also crucial. Note that a change of about 10 mm on a 100-mm visual analog scale is considered clinically significant (Vautier, 2011). In fact, with its good psychometric properties, the visual analog scale reveals numerous benefits over other pain assessments.

Usage and Applications of Visual Analog Scales

The visual analog scale can be applied across numerous clinical settings. The instrument, for instance, is highly beneficial in the measurement of the unidimensional aspects of pain. Patients express preferences of visual analog scales over verbal rating scales as visual analog scales do not limit responses to a number of pain categories (Aicher et al., 2012). Note that when it comes to verbal rating scales, the use of an uneven number of descriptors often leads to regression towards the mean, while the use of more than seven descriptors decreases the reliability of the scale.

Interestingly, Aicher and colleagues assessed the performance of the visual analog scale in patients suffering from severe headaches. Patients were required to draw a line on a 100-mm vertical scale. Visual analog scales showed better sensitivity and acceptance compared to verbal rating scales. As the scale represents a continuous line, the visual analog method reveals high sensitivity. Note that previous research revealed the superiority of the combination of acetylsalicylic acid, paracetamol, and caffeine over the combination without caffeine or the single preparations.

Visual analog scales can be applied to other subjective phenomena, such as tense arousal and mood. The visual analog scale can be used across numerous settings:

  • Mood and depression: Mood assessments and journals are essential for one’s well-being. The visual analog scale, in particular, can help experts detect the first signs of depression which can improve treatment. Research shows that the visual analog scale is a useful tool in the assessment of depressive symptoms, including depression in elderly and cognitively impaired patients.
  • Asthma: Visual analog scales can also benefit the assessment of asthma and dyspnoea. In the evaluation of asthma, the visual analog scale can include the following extremes: “no breathlessness” and “greatest breathlessness.” Research shows that the scale can be used as an alternative to a diary in adolescents.
  • Appetite and dyspepsia: Visual analog scales are widely used in taste and appetite research. The scales can assess several aspects, such as food intake, appetite, hunger, and perceptions of fullness. In addition, the visual analog scale is beneficial in the assessment of dyspepsia and gastrointestinal problems. Research shows that the tool is reliable, sensitive to change, and well-accepted.
  • Ambulation and gait: Visual analog scales benefit the assessment of ambulation and gait. Note that ambulation refers to one’s mobilization after surgery. In children, the visual analog scale reveals high levels of compliance as the tool is easy and quick to administer. We should mention that the faces rating scale is a popular variation suitable for pediatric populations.
  • Fatigue and energy: Measuring fatigue can be challenging. Fatigue is often accompanied by headaches, depression, and sleepiness. In fact, tiredness can be caused by chronic pain. Research shows that patients with arthritis often experience fatigue. Thus, the visual analog scale becomes a crucial tool which can be implemented in the successful assessment and treatment of chronic fatigue.
  • Quality of life: The visual analog scale has been extensively employed in the evaluation of one’s health-related quality of life. Because of the simplicity of the scale, the visual analog measurement is a vital tool in digital health practices worldwide. Note that with the increasing role of patients in medical decision-making, health-related quality of life becomes a focus of digital health research. Medical interventions and care should tackle not only overall survival but patients’ quality of life and well-being.

Visual Analog Scales and Labor Pain

With its numerous benefits in practice and high psychometric properties, the visual analog scale becomes an essential instrument in the assessment of labor pain. Pain assessment during labor requires specific considerations as pain experience is influenced by individual factors, cultural differences, and gestational age. Examining labor pain is essential in the effective administration of analgesia and patients’ safety (Wei et al., 2010). Note that in some parts of the world, maternity mortality rates are high, and often caused by the dismissal of reported pain during birth and postpartum.

Thus, the selection of a reliable, valid, and sensitive tool is crucial. Research shows that the visual analog scale can be a useful instrument in the assessment of pain intensity during labor. Effective pain assessment requires more than one recording over time. On top of that, pain assessment must tackle the psychological aspects of pain experiences, as well as the overall emotional significance of childbirth.

Digital Visual Analog Scales and Health Technologies

Visual analog scales are powerful tools. Although visual analog scales do not impose problems for translation and scoring, there’s a high risk of drawing ambiguous lines. Therefore, the electronic format of the visual analog scale becomes an essential and preferred tool in pain assessment (Delgado et al. , 2018). Delgado and colleagues asked 100 patients (>18 years) to record their pain experiences using a paper form and a digital version of the test. A mixed-model analysis of covariance with the Bonferroni post hoc test was performed to analyze any differences between paper and digital scores. In addition, a Bland-Altman analysis was done to assess the instrument agreement between the two versions of the test. No significant differences between the paper and the laptop version and no clinical differences between the paper and the digital version were observed.

Generally speaking, subjective scales are popular tools in today’s health care industry. Self-reports empower patients and electronic tools allow vulnerable patients and those living in remote locations to access medical care and treatment. It’s not a secret that some health data can be obtained only from the patient, so patient-reported outcomes and measurements become fundamental. In addition, health technologies benefit the implementation of patient-reported tools and data interoperability in practice.

Visual Analog Scales and Pain Assessment: Conclusion

The visual analog scale is among the most popular pain assessments which benefit research and medical care. The scale consists of a 10-cm line on which patients can rate their pain experience. The scale reveals good psychometric qualities and high compliance. With its numerous strengths, the visual analog scale can be implemented across various settings, such as childbirth, hip pain, etc. It can be used to assess pain progression and compare pain experiences between patients. This scale is also a valuable tool in the assessment of depression, appetite, and asthma. The digital version of the visual analog scale, in particular, can revolutionize pain assessment and treatment. Both the mobile and the laptop version of the scale improve user experience and data interoperability.

To sum up, as pain is a personal experience, pain assessment often challenges researchers and health providers. The selection of a reliable tool is paramount to improve pain assessment and treatment. Subjective instruments, in particular, are crucial in today’s patient-driven health care industry; such tools provide information which medical tests may fail to notice. Research shows that visual analog scales are valid and reliable tools in digital health, which can empower patients and improve health-related quality of life. In the end, patients’ quality of life and well-being are paramount – and patients deserve a pain-free life.

Visual Analog Scales and Pain Assessment: Conclusion

Aicher, B., Peil, H., Peil, B., & Diener, H. (2012). Pain measurement: Visual Analogue Scale (VAS) and Verbal Rating Scale (VRS) in clinical trials with OTC analgesics in headache. Cephalalgia, 32 (3), p. 185-197.

Delgado, D., Lambert, B., Boutris, N., McCulloch, P., Robbins, A., Moreno, M., & Harris, J. (2018). Validation of Digital Visual Analog Scale Pain Scoring With a Traditional Paper-based Visual Analog Scale in Adults. Journal AAOS, 2 (3).

Kliger, M., Stahl, S., Haddad, M., Suzan, E., Adler, R., & Eisenberg, E. (2015). Measuring the Intensity of Chronic Pain: Are the Visual Analogue Scale and the Verbal Rating Scale Interchangeable?  Format: Abstract. Pain Practice, 15 (6), p. 538-547.

Safikhani, S., Gries, K., Trudeau, J., Reasner, D., Rudell, K., Coons, S., Bush, E., Hanlon, J., Abraham, L., & Vernon, M. (2018). Response scale selection in adult pain measures: results from a literature review. Journal of Patient-reported Outcomes.

Vautier, S. (2011). Measuring change with multiple visual analog scales: Application to tense arousal.  European Journal of Psychological Assessment, 27(2), 111-120.

Wei, C., Leng, C., & Siew Lin, S. (2010). The use of the Visual Analogue Scale for the assessment of labour pain: a systematic review. JBI Library of Systematic Reviews, 8(24), p. 972-1015.