Background & Aims

Pain is the defining feature of the low back pain experience; how it is measured is vital to patients, clinicians, and researchers1,2 to monitor clinical progress and evaluate treatment effectiveness in randomised controlled trials3,4. In low back pain trials, pain intensity, a core outcome domain5, is often evaluated using the numerical rating scale and visual analogue scale6. Despite their widespread use, limited high-quality evidence exists regarding the measurement properties of the numerical rating scale and visual analogue scale in individuals with low back pain7, potentially constraining their utility in research and practice. This study assesses the test-retest reliability and measurement error of the numerical rating scale and visual analogue scale in individuals with acute and chronic non-specific low back pain.

Methods

This study used a test-retest longitudinal design to determine the reliability and measurement error of the numerical rating scale and visual analogue scale in people with non-specific low back pain via online administration. Participants recorded their pain intensity on both scales at the beginning of the survey (baseline) and at two retest intervals: 20-minutes and 24-hours after baseline. Intraclass correlation coefficients (agreement), the standard error of measurement (agreement) and the smallest detectable change were determined separately for people with acute and chronic low back pain for two recall periods (report average pain intensity over the last 24 hours and last 7 days).

Results

A total of 298 and 242 participants completed the 20-minute and 24-hour follow-ups, respectively. Test-retest reliability values for the numerical rating scale were good to excellent (intraclass correlation coefficient 0.75 to 0.94) over both retest intervals in both people with acute and chronic low back pain. The smallest detectable change ranged from 1.6 to 2.8 of 10 for the numerical rating scale. Test-retest reliability values for the visual analogue scale were moderate to good (intraclass correlation coefficient 0.68 to 0.89) over both retest intervals in both people with acute and chronic low back pain. The smallest detectable change for the visual analogue scale ranged from 20.9 to 36.5 of 100. Our results suggest the reliability of the numerical rating scale and visual analogue scale is acceptable, however their measurement errors are higher than generally accepted minimal important change scores6, which needs to be considered when interpreting trial results and measuring pain in clinical practice.

Conclusions

The numerical rating scale and visual analogue scale are both reliable measures to assess pain intensity in a sample of Australian adults with low back pain. The numerical rating scale has marginally better reliability and measurement error compared to the visual analogue scale and may be more appropriate for use in this population. However, the smallest detectable change values for both measurement tools were higher than the currently used minimal important change, warranting careful interpretation of changes in pain intensity scores recorded in adults with low back pain.

References

1.Kamper, S. J. et al. Measuring Pain Intensity in Patients with Neck Pain: Does It Matter How You Do It? Pain Practice 15, 159–167 (2015).
2.Ferreira, M. L. et al. Global, regional, and national burden of low back pain, 1990–2020, its attributable risk factors, and projections to 2050: a systematic analysis of the Global Burden of Disease Study 2021. Lancet Rheumatol 5, e316–e329 (2023).
3.Hush, J. M., Refshauge, K. M., Sullivan, G., De Souza, L. & McAuley, J. H. Do Numerical Rating Scales and the Roland-Morris Disability Questionnaire capture changes that are meaningful to patients with persistent back pain? Clin Rehabil 24, 648–657 (2010).
4.Henry, S. G., Bell, R. A., Fenton, J. J. & Kravitz, R. L. Goals of Chronic Pain Management: Do Patients and Primary Care Physicians Agree and Does it Matter? Clinical Journal of Pain 33, 955–961 (2017).
5.Chiarotto, A. et al. Core outcome domains for clinical trials in non-specific low back pain. Eur Spine J 24, 1127–1142 (2015).
6.Kovacs, F. M. et al. Minimal Clinically Important Change for Pain Intensity and Disability in Patients With Nonspecific Low Back Pain. Spine (Phila Pa 1976) 32, 2915–2920 (2007).
7.Chiarotto, A. et al. Measurement Properties of Visual Analogue Scale, Numeric Rating Scale, and Pain Severity Subscale of the Brief Pain Inventory in Patients With Low Back Pain: A Systematic Review. J Pain 20, 245–263 (2019).

Presenting Author

Sam Williams

Poster Authors

Sam Williams

BSc(Hons)

Neuroscience Research Australia

Lead Author

Saurab Sharma

Neuroscience Research Australia

Lead Author

Aidan Cashin

UNSW/Neuroscience Research Australia

Lead Author

Matthew Jones

UNSW/NeuRA

Lead Author

Alessandro Chiarotto

Erasmus MC/Vrije Universiteit Amsterdam

Lead Author

Harrison Hansford

UNSW/NeuRA

Lead Author

Martjie Venter

NeuRA

Lead Author

Michael Wewege

Lead Author

Michael Ferraro

UNSW/NeuRA

Lead Author

Jack Devonshire

UNSW/NeuRA

Lead Author

Sylvia Gustin

UNSW/NeuRA

Lead Author

Raymond Ostelo

Lead Author

Topics

  • Assessment and Diagnosis