Abstract:
Pain is one of the leading causes of health care utilisation in the world. However, the complex interactions between the physiological and psychosocial factors involved in the experience of pain are not well understood. This issue becomes more complex when individuals from different ethnic and cultural backgrounds are involved. It is well established that people of different ethnic backgrounds possess unique attitudes, perceptions and reactions to pain; yet whether differences in the physiological processing of pain between ethnic groups exists remains uncertain. Despite this issue being of particular relevance to New Zealand, where ethnic disparities in the reporting and management of clinical pain are found to exist, there is lack in research looking into the mechanisms driving these disparities. The current study aimed to experimentally investigate both behavioural and physiological responses to a painful task and a worry induction task, in a sample of Maori, Pacific Island and European individuals. It also aimed to investigate the role of 'pain catastrophising' in the relationship between ethnicity and pain. Some have suggested that levels of 'general worry' may mediate the influences of catastrophic thoughts about pain on the pain experience. On this basis, the final aim of the study was to explore the relationship between general worry and pain catastrophising, and the impact these variables had on performance at the painful task and worry induction task. Sixty-four healthy volunteers were recruited and each were separately exposed to a painful cold pressor task (physical stressor), and a worry induction task (mental stressor). Pain tolerance, pain threshold, and subjective pain ratings were assessed. Physiological responses to the pain and worry tasks were assessed by monitoring participants' Heart Rate (HR) and Heart Rate Variability (HRV). HRV provides insight into the cardiovascular systems ability to effectively respond to stressors such as pain and worry. The relationship between these behavioural and physiological outcome measures were compared to participants' self-reported catastrophic thoughts about pain and other psychosocial variables found to impact the pain experience. Maori, Pacific and European participants were not found to significantly differ in their behavioural and physiological responses to the pain and worry tasks. However, Maori and Pacific Island participants showed significantly healthier physiological recovery patterns from the pain task compared to European participants. Further, higher baseline 'high frequency' HRV was found to be significantly linked with higher pain tolerance. Pain catastrophising levels were not found to significantly differ between ethnic groups, hence conclusions about its mediating influences could not be established. Nonetheless, pain catastrophising was found to be significantly, positively associated with general worry. This research suggests that factors outside of a controlled experimental context may be responsible for differences in clinical pain reports between Maori, Pacific Island and European peoples. The ethnic differences in HRV recovery from the pain task, suggest differences in autonomic cardiovascular stress modulation between these groups. This research provides a platform for future research aimed at making the treatment of pain in clinical settings more ethnically sensitive. It also provides a motive for further research looking into the characteristics of cardiovascular stress modulation in these groups.