Background & Aims
In chronic pain patients, pain intensity tends to fluctuate from day to day (1). This tendency to demonstrate fluctuating pain (within-subject variability (WSV) of clinical pain reports has been identified as a predictor of the placebo response (1,2). WSV of pain intensity reports could be also assessed via the Focused Analgesia Selection test (FAST), which is based on experimentally induced pain, which was also found to predict the placebo response in clinical trials (4,5). These, findings could be explained by the Bayesian theorem (3). To better understand the relationships between the WSV of pain intensity reports, either clinical or experimentally induced, with the placebo response, we invited fibromyalgia patients to participate in a study in which a robust experimental placebo manipulation has been conducted, alongside the assessment of WSV. The aim was to explore possible associations between the results of the placebo manipulation and the WSV of pain intensity reports.
Methods
Fibromyalgia patients were recruited based on predetermined inclusion/exclusion criteria, using social media platforms and notice board fliers at Haifa University campus.
Eligible participants signed informed consent before receiving an online pain diary to evaluate clinical pain variability. During a single lab meeting, participants underwent an assessment of experimental pain variability using the FAST and also underwent the Colloca placebo paradigm.
Results
Thirty-one Fibromyalgia completed the study (study is ongoing). FAST ICC was found to positively correlate with changes in pain during the conditioning phase (r=0.604, p=0.001). Clinical within-subject’s variability demonstrated a trend toward significant correlation (r=0.336, p=0.065) with changes in pain during the conditioning phase.
In addition, expectations after the conditioning phase negatively correlated with pain variability (R2 power r=-0.756 p<0.001, ICC r=-0.440, p=0.013).
Conclusions
Our findings demonstrate a distinct correlation between experimental as well as a clinical WSV of pain intensity reports and the results of the conditioning phase of the placebo paradigm. The meaning and potential clinical implications of these findings still require further research.
References
(1) Farrar, J. T., Troxel, A. B., Haynes, K., Gilron, I., Kerns, R. D., Katz, N. P., Rappaport, B. A., Rowbotham, M. C., Tierney, A. M., Turk, D. C., & Dworkin, R. H. (2014). Effect of variability in the 7-day baseline pain diary on the assay sensitivity of neuropathic pain randomized clinical trials: An ACTION study. Pain, 155(8), 1622–1631. https://doi.org/10.1016/j.pain.2014.05.009
(2) Harris, R. E., Williams, D. A., McLean, S. A., Sen, A., Hufford, M., Gendreau, R. M., Gracely, R. H., & Clauw, D. J. (2005). Characterization and consequences of pain variability in individuals with fibromyalgia. Arthritis & Rheumatism, 52(11), 3670–3674. https://doi.org/10.1002/art.21407
(3) Kuperman, P., Talmi, D., Katz, N., & Treister, R. (2020). Certainty in ascending sensory signals – The unexplored driver of analgesic placebo response. Medical Hypotheses, 143, 110113. https://doi.org/10.1016/j.mehy.2020.110113
(4) Triester R., Eaton T., Trudeau J. J., Elder H., & Katz N. P. (2017). Development and preliminary validation of the focused analgesia selection test to identify accurate pain reporters. 10, 319–326. https://doi.org/10.2147/jpr.s121455
(5) Treister, R., Honigman, L., Lawal, O. D., Lanier, R. K., & Katz, N. P. (2019). A deeper look at pain variability and its relationship with the placebo response: Results from a randomized, double-blind, placebo-controlled clinical trial of naproxen in osteoarthritis of the knee. Pain, 160(7), 1522–1528. https://doi.org/10.1097/j.pain.0000000000001538
Presenting Author
Galia Emergui
Poster Authors
Topics
- Assessment and Diagnosis