Effects of opioid rotation to buprenorphine/naloxone on pain, pain thresholds, pain tolerance, and quality of life in patients with chronic pain and opioid use disorder.

ABSTRACT Long-term opioid use in patients with chronic non-cancer pain (CNCP) can lead to opioid use disorder (OUD) and has been associated with hyperalgesia and reduced quality of life. Studies suggest anti-hyperalgesic properties of buprenorphine, and buprenorphine/naloxone (BuNa) has shown beneficial effects on quality of life in OUD patients without CNCP. This study investigated the added value of BuNa in CNCP patients with OUD on self-reported pain, pain thresholds, pain tolerance, and quality of life (QoL). In the current study, forty-three outpatients with CNCP and OUD were included for inpatient conversion from full μ-receptor agonist opioids to BuNa. Self-reported pain, pain thresholds, pain tolerance, and QoL were determined at baseline and after two months of follow up, using respectively a Visual Analogue Scale (VAS-pain and VAS-QoL), Quantitative Sensory Testing (QST), and Euro-Qol-5-dimensions (EQ-5D). In total 37 participants completed the protocol, and their data were analyzed. The mean VAS-pain score decreased from 51.3 to 37.2 (27.5%, F=3.3; p= 0.044), while the pressure pain threshold and electric pain threshold/tolerance increased after substitution (F=7.8; p=0.005 and F=44.5; p<0.001, respectively), as well as QoL (EQ-5D questionnaire: F=10.4; p=0.003 and VAS-QoL: F=4.4; p=0.043). We found that conversion of full μ-receptor agonists to BuNa, in patients with CNCP with OUD, was accompanied with lower self-reported pain, higher pain thresholds, higher pain tolerance, and improved QoL. Despite several study limitations, these data suggest that BuNa might be of value in CNCP patients with OUD. Future studies should investigate long-term effects of BuNa in randomized trials.