Background & Aims

Pain assessment is difficult because it is a subjective experience. The gold standard for pain assessment in clinical practice is self-report measures. However, self-reported pain assessments cannot adequately evaluate pain in individuals who are unable to verbally express their pain. The Abbey Pain Scale (APS), a commonly used behavioral observational assessment of pain, has demonstrated validity through its correlation with subjective pain intensity and changes in scores before and after pain treatment. However, it remains unclear whether APS scores accurately reflect the subject’s pain because the study was conducted in elderly patients with dementia, who often exhibit low reliability in reporting subjective pain intensity.
The main objective of this study was to investigate whether behavioral observation assessment, particularly APS, reflect the degree of individuals’ pain and the intensity of nociceptive stimuli.

Methods

The study divided healthy adult volunteers into two groups: six subjects who received experimental nociceptive stimuli and 23 evaluators who assessed pain using the APS.. A mechanical nociceptive stimulus was used to video-record the behavioral responses for subsequent analysis. Nociceptive stimulation was applied using a digital pneumatic tourniquet around the lower leg and cuff pressures of 200, 400, and 600 mmHg for 5 s. After the stimuli, the subjects were asked to rate the degree of pain they experienced on the Numerical Rating Scale (NRS). The evaluator watched the video footage and rated the subjects’ pain using the APS for each video.
The primary objective was to determine whether APS as well as subjective pain intensity increased nociceptive stimulus intensity. As secondary outcomes, the distribution of NRS and APS scores was examined in histograms. In addition, the scores for each sub-item of the APS were summed.

Results

The subjective pain intensity experienced by subjects due to mechanical nociceptive stimulation, as measured by NRS, was 2.2 (±0.7), 4.5 (±0.5), and 6.8 (±0.4) at cuff pressures of 200, 400, and 600 mmHg, respectively. Pain ratings by evaluators using the APS through video-based behavioral observation were 0.4 (±0.8), 1.4 (±1.0), and 2.1 (±1.7). Significant differences were observed in both NRS and APS scores across varying cuff pressures. Post-hoc analysis revealed progressive increases in both NRS and APS scores with escalating cuff pressures. A significant correlation was identified between NRS and APS scores (rs=0.55, p=1.48×10^-28). The NRS distribution histogram displayed a trimodal pattern, while the APS histogram exhibited a left-skewed distribution, predominantly under two points. The aggregate scores for the APS sub-items “Facial Expression” and ” Change in Body Language'” were notably higher.

Conclusions

APS, a behavioral observation assessment, was shown to vary depending on the intensity of nociceptive stimuli. However, the range of APS changes in this study involving healthy subjects was limited, and discrepancies were observed where subjects with intense subjective pain were sometimes assessed as ‘no pain’ by APS. This suggests that relying solely on APS for pain assessment in individuals capable of verbalizing pain may be insufficient.
Furthermore, when pain behaviors in healthy subjects were evaluated using APS, it was found that the scores for the sub-items ‘Facial Expression’ and ‘Change in Body Language’ were notably higher. The American Geriatrics Society recommends focusing on ‘Facial Expression,’ ‘Body Movement,’ and ‘Vocalization,’ when assessing pain in patients with dementia through observation. This study indicates that, beyond dementia patients, attention to ‘Facial Expression’ and ‘Body Movement’ is essential for evaluating pain through behavioral observation.

References

[1]Abbey J, Piller N, Bellis AD, Esterman A, Parker D, Giles L, Lowcay B. The Abbey pain scale: a 1-minute numerical indicator for people with end-stage dementia. International journal of palliative nursing. 2004; 10:6-13.
[2]Takai, Yukari, et al. “Abbey Pain Scale: Development and validation of the Japanese version.” Geriatrics & gerontology international 2010; 10:145-153.
[3]Kappesser J, Voit S, Lautenbacher S, Hermann C. Pain assessment for cognitively impaired older adults: Do items of available observer tools reflect pain?specific responses? European Journal of Pain. 2020; 24:851-62.
[4]Strand LI, Gundrosen KF, Lein RK, Laekeman M, Lobbezoo F, Defrin R, Husebo BS. Body movements as pain indicators in older people with cognitive impairment: A systematic review. European Journal of Pain. 2019; 23:669-85.

Presenting Author

Kazuhiro Shimo

Poster Authors

Kazuhiro Shimo

PhD

Kobe Gakuin University

Lead Author

E-mail

Satoshi Ohga

Kobe Gakuin University

Lead Author

E-mail

Takafumi Hattori

Kobe Gakuin University

Lead Author

E-mail

Yoshiki Maruyama

Tanaka Orthopedic Clinic

Lead Author

E-mail

Koichi Tanaka

Tanaka Orthopedic Clinic

Lead Author

E-mail

Takako Matsubara

Kobe Gakuin University

Lead Author

E-mail

Topics

  • Assessment and Diagnosis