Associations Between Different Laboratory-Evoked Measures of Pain: A Human Laboratory Examination

Abstract ID 94973 Poster Board 307 Background: Laboratory measures of pain (quantitative sensory testing, QST) assess pain sensitivity across several indices (e.g., heat pain, cold pain, pressure pain, etc.) hypothesized to derive from different physiological origins. Little is known regarding the association between the QST outcomes or the overlap between QST assays. Understanding whether QST assays measure overlapping domains will help refine and inform assessments of analgesic response. Methods: These analyses collapse data from 3 human behavioral pharmacological studies that administered QST to healthy men and women to assess the relationship between different QST measures of acute and chronic pain and explore whether they measure unique or overlapping domains. Acute mechanical pain was assessed using pressure pain threshold (kPa) and mechanical temporal summation. Acute temperature-induced pain was assessed as the time to remove a hand from cold water immersion and the time of detection and task discontinuation following thermal (heat) exposure, as well as pain ratings following repeated thermal exposure. Capsaicin (10% topical cream) was used to model chronic pain conditions wherein pain was rekindled throughout the day by applying a thermal or mechanical stimulus to the sensitized site to assess threshold and pain response. Finally, two combined QST tasks were used to measure endogenous opioid tone including cold pressor/mechanical temporal summation and cold pressor/pressure pain. Intercorrelations between ratings were assessed using Spearman correlations. Non-parametric Mann-Whitney U tests and Spearman correlations were used as appropriate to examine the relationship between age and gender with QST ratings as well as two global QST measures of sensitivity and central sensitization. Results: Participants (N = 106) were 32.7 (SD = 9.6) years old, 45% male/48%female, 43% Caucasian/While, 37% African American, and 12% Asian. Data revealed strong correlations between thermal pain threshold (r(66) = .36, p = .003) and tolerance (r(66) = .25, p = 0.04) with pain derived following thermal exposure to the capsaicin-sensitization site (r(66) = .29, p = 0.03). Pressure pain was also negatively correlated with response to the combined cold pressor/pressure pain task (r(106) = -.40, p Conclusions: These data demonstrate that overlapping outcomes were primarily relegated to unique domains, suggesting the QST battery was assessing independent pain constructs. This supports the notion that a comprehensive QST battery can be used to measure pain of different origins, which has important implications for the development of analgesic compounds. Data also highlight that sensitivity to specific QST domains may be influenced by factors such as gender. Funding: R01DA035246, R01DA040644, R01DA042751, R01DA056045, R01DA052937