Psycho-physiological response to pain among individuals with comorbid pain and opioid use disorder: Implications for patients with prolonged abstinence.

Background: Individuals with comorbid opioid addiction and pain (COAP) relapse 3-5 times more often than patients with opioid use disorder (OUD) but without pain. However, psychophysiological responses to pain among a COAP population are unknown. Objectives: We hypothesized that those on Medications for Opioid Use Disorder (MOUD) with chronic pain, relative to opioid-naïve chronic pain individuals, would show greater psycho-physiological pain reactivity and slower recovery when exposed to acute pain. Methods: Four groups with chronic pain were recruited (N = 120; 60% Female): 1) MOUD-methadone; 2) MOUD-buprenorphine; 3) history of completed MOUD with prolonged opioid abstinence (PA; Mabstinence = 121 weeks; SD = 23.3); and 4) opioid-naïve. We assessed heart rate (HR), galvanic skin conductance (GSC), peripheral temperature, and frontalis electromyography (EMG) during a cold pain task. Results: MOUD subjects had delayed HR reactivity to pain compared to those not on MOUD (PA & opioid-naïve; F(3,119) = 2.87, p < .04). The PA group showed a normal HR reactivity pattern, but had higher HR compared to the opioid-naïve group. The GSC group x time analysis showed the PA group had greater baseline levels and pain reactivity than the other groups (F(3,119) = 3.84, p < .02). The opioid-naïve group had lower reactivity on peripheral temperature compared to other groups (F(3,119) = 9.69, p < .001). Conclusion: Greater psychophysiological reactivity to pain was experienced by co-morbid OUD/chronic pain subjects who had been opioid abstinent for an extended period, possibly due to the lack of a buffering effect of opioid agonists. These subjects may develop coping skills to tolerate pain distress, thereby avoiding relapse in response to pain triggers. Understanding how pain creates more intense psychophysiological responses among COAP patients may lead to better treatments.