Racial/ethnic differences in experimental pain sensitivity and associated factors - Cardiovascular responsiveness and psychological status

Abstract

Background Racial/ethnic disparities related to pain in the US have been reported that racial/ethnic minorities have greater levels of chronic pain and receive lower quality of care. Underlying mechanisms to explain the racial/ethnic differences in pain is unclear. Enhanced experimental pain sensitivity is suggested to be associated with ethnic differences in clinical pain. Purpose To examine racial/ethnic differences in experimental pain sensitivity, and evaluate contribution of cardiovascular responsiveness and psychological status to racial/ethnic differences in experimental pain sensitivity. Methods The baseline data of TMD-free 3,159 individuals - non-Hispanic white (NHW): 1,637, African-American (AA): 1,012, Asian: 299, and Hispanic: 211 - from the OPPERA prospective cohort study were used. Quantitative sensory testing measures for pressure, mechanical cutaneous, and heat pain were used. Cardiovascular responsiveness measures (e.g., BP, HR, HR/MAP ratio, and heart rate variability) and psychological status (depression, anxiety, stress, coping, and catastrophizing) were included in the analyses. Structural equation modeling with maximum likelihood estimation method was used for mediation analyses. Putative mediators that showed significant racial/ethnic differences were entered into the final models simultaneously with age, gender, BMI, study site, education and income level as covariates. Results Racial/ethnic minorities showed higher pain sensitivity, including heat pain tolerance, heat pain rating (HPR), heat pain aftersensation (HPA), mechanical cutaneous pain ratings and aftersensation (MCPRAS), and mechanical cutaneous pain temporal summation (MCPTS), compared to NHWs. Catastrophizing significantly mediated the associations between ethnicity and pain sensitivity (heat pain tolerance, HPR, HPA, MCPRAS, and MCPTS) for both AAs and Asians, compared to NHWs. Coping negatively mediated the association between race/ethnicity and heat pain tolerance, HPR, and MCPTS in both AAs and Asians, compared to NHWs. HR/MAP ratio showed a significant negative mediating effect on the association between race/ethnicity (AAs vs. NHWs) and heat pain tolerance. Negative emotion mediated the associations between race/ethnicity (Asians vs. NHWs) and mechanical cutaneous pain threshold, HPR, and MCPRAS. Conclusion The identified mediators should be considered in pain management programs to implement better strategies to reduce clinical pain, especially for AAs and Asians in the US. Further clinical research is required to increase our understanding of the suggested mechanisms.