Altered pain thresholds during and after opioid withdrawal in patients with chronic low back pain

Background. Opioids as the strongest pain drugs are often used for chronic pain although their long-term efficacy has not yet been clarified. In this longitudinal study, we compared the pain sensitivity of patients with chronic low back pain (cLBP) under long-term opioid use and treated with multidisciplinary pain therapy. Methods. The pain sensitivity was measured by the quantitative sensory testing (QST) technique at admission, discharge and 6 months after the beginning of the study in 34 patients with both cLBP and opioid medication, 33 opioid-naive cLBP patients and those neither with pain nor opioid use (HC). Both patient groups underwent a 3-week multidisciplinary pain therapy (MDPT). Results. Under opioid use, the patients showed significantly lower cold and heat pain thresholds compared to HC and delayed reaction to warm stimuli. After 3 weeks of MDPT, opioid-positive patients still had a lower pain threshold to cold and heat stimuli, while opioid-naive patients normalised their pain perception. Conclusion. Our findings suggest that long-term use of opioids intensifies the peripheral sensitisation of cLBP. The MDPT can counteract this process.