Ethnic Disparities in Total Joint Arthroplasty: Pain and Stress-Related Media

与膝骨关节炎（OA）相关的疼痛具有以下特征：(a)个体间的高度可变性；(b)与组织损伤的放射测量有一定的关联。种族背景是影响疼痛报告和疼痛相关行为差异的一个重要因素。最近的研究表明，与白人相比，非洲裔美国人表现出较低的疼痛耐受水平和相对受损的疼痛调节机制（例如，对压力源的血压反应）。也有证据表明，内源性阿片释放有助于这些机制的功能。总体目标

Pain associated with knee osteoarthritis (OA) is characterized by (a) high levels of variability among individuals; and (b) modest associations with radiographic measures of tissue damage. Ethnic background is one important factor that contributes to variation in pain reports and pain-related behavior. Recent studies indicate that African-American, compared to white, individuals exhibit lower pain tolerance levels and relatively impaired pain regulatory mechanisms (e.g., blood pressure responses to stressors). There also is evidence that endogenous opioid release contributes to the function of these mechanisms. The overall aim of the proposed study, then, is detemine whether changes in opioid neurotransmission evoked by thermal heat stimulation partially mediate ethnic differences in thermal pain responses among patients with knee OA. Thirty-six men (18 African-American, 18 white) with knee OA will undergo PET bain imaging with the opiodergic radioligand [18F] fluoroethyl-diprenorphine under two conditions: (a) exposure to thermal heat stimulation, tailored to individual pain thresholds, that will produce similar, moderate, levels of thermal pain intensity across patients; and (b) exposure to thermal heat stimulation that will produce perceptions of warmth across patients (sensory control condition). Patients will produce visual analogue scale (VAS) ratings of pain intensity and unpleasantness following stimulation. We expect that African-American, compared to white patients, will (a) produce significantly greater increases in pain unpleasantness ratings; and (b) exhibit lower opioid neurotransmission in medial pain system structures (e.g., amygdala, anterior cingulate cortex) from sensory control to painful thermal heat stimulation, even after controlling for psychosocial variables such as depressive symptom levels. We also expect that stimulation-evoked change in opioid neurotransmission in medial pain system structures will partially mediate the ethnic group difference in change in pain unpleasantness ratings. We anticipate that the proposed research will generate new sttudies that will lead to (a) improved understanding of additional physiologic or psychosocial variables that contribute to ethnic differences in pain responses and endogenous pain regulatory function; (b) development of new or refinement of current pharmacologic or behavioral/psychosocial interventions for pain management; and (c) reductions in ethnic disparities in patients' expectations of and preferences for these interventions.