Background & Aims
Calibration enables the intensity of the pain stimulus to be matched to the individual sensitivity of the participant (1, 2). Such a procedure, which provides a similar pain experience for all test participants, affects the reliability and accuracy of the results obtained. Moreover, inadequate calibration, or lack thereof, can lead to the application of a pain stimulus that exceeds a person’s tolerance threshold. Such a situation would be inconsistent with the guidelines of the International Association for the Study of Pain (3) and the general principles of conducting research with human participants (4). The main aims of the data analysis of the three experimental pain studies were as follows:
1 to evaluate the effectiveness of the calibration methods used
2 to compare the calibration methods with each other
3 to identify the most effective calibration methods
4 to identify factors affecting the effectiveness of calibration
5 suggest improvements to current calibration methods.
Methods
Experimental data from three pain studies were analysed. Data from a total of 200 healthy participants (80 males) aged 18-55 were included. The effectiveness of the calibration methods was assessed using data from calibration measurements and pretests. In addition, data such as the pain rating scale and its anchoring, the instructions that the participants received, the construction of the pain stimulus and the length of the intervals between stimuli and subsequent calibration series were included. Moreover, various methods of individual pain stimulus matching (Study 1 – increasing calibration; Study 2 – increasing calibration with correction; Study 3 – increasing calibration with a series of pseudorandom stimuli), as well as a mathematical function by which the final intensity of the pain stimulus applied in the successive stages of the experimental study was calculated were analysed.
Results
In Study 1, pain stimuli were calibrated so participants rated the intensity as 50 on the VAS (0-100). In the pretest, on average, participants rated the intensity of the stimulus as 53.37 (SD=19.40). Me=65, Mo=67. The lowest rating was 0, while the highest was 100. In Study 2, pain stimuli were calibrated so participants rated the intensity as 5 on NRS (0-10). In the pretest, on average, participants rated the intensity of the stimulus as 4.77 (SD= 1.70). Me and Mo values were 5. The lowest rating was 1, while the highest was 9. In Study 3, pain stimuli were calibrated so participants rated the intensity as 5 and 6 on NRS (0-10). In the pretest, stimuli that were supposed to induce pain 5/10, were rated at 4.44 (SD=1.45) on average. The Me and Mo values were 4. The lowest score was 2, and the highest score was 9. Meanwhile, the stimuli that were supposed to induce pain 6/10, were rated at 5.10 (SD=1.40). The Me and Mo values were 5. The lowest rating was 2 and the highest was 8.
Conclusions
In Study 2, it was possible to match the intensity of the pain stimulus most precisely. This result suggests that increasing calibration (Study 1) may not be sufficient for accurate individual calibration of pain stimuli, and a correction may need to be performed to increase the precision of individual matching of pain stimulus intensity. It also appears that a series of random stimuli (Study 1) contributed to a more accurate matching of pain stimulus intensity than a series of pseudorandom stimuli (Study 3). The results of future research may contribute to the development of standards and guidelines for calibrating pain stimuli. It would be worthwhile to explore in future studies whether body build, and body composition (including, but not limited to body fat and muscle content) will affect calibration effectiveness. Research can also incorporate physiological parameters into the calibration process providing additional information regarding the response to pain stimuli.
References
1. Adamczyk, W. M., Szikszay, T. M., Nahman-Averbuch, H., Skalski, J., Nastaj, J., Gouverneur, P., & Luedtke, K. (2022). To Calibrate or not to Calibrate? A Methodological Dilemma in Experimental Pain Research. Journal of Pain, 23(11), 1823–1832. https://doi.org/10.1016/j.jpain.2022.07.007
2. ?wider, K., Bruña, R., & Moratti, S. (2023). How to make calibration less painful — a proposition of an automatic, reliable and time-efficient procedure. Preprint. https://doi.org/10.22541/AU.167501165.53064972/V1
3. International Association for the Study of Pain. (n.d.). Ethical Guidelines for Pain Research in Humans. Retrieved October 12, 2023, from https://www.iasp-pain.org/resources/guidelines/ethical-guidelines-for-pain-research-in-humans/
4. World Medical Association. (2013). World Medical Association Declaration of Helsinki: Ethical Principles for Medical Research Involving Human Subjects. JAMA, 310(20), 2191–2194. https://doi.org/10.1001/JAMA.2013.281053
Presenting Author
Julia Badzi?ska
Poster Authors
Topics
- Assessment and Diagnosis