Increased Pain Sensitivity in Patients with Chronic Pain Who Developed Opioid Use Disorder

The clinical relevance of increased pain sensitivity in patients prescribed opioids for chronic pain is unclear. If increased pain sensitivity predicted the development of opioid use disorder (OUD) in this group, it could provide a more objective criterion for risk stratifying patients who are being considered for chronic opioid therapy. This study hypothesized that differences in pain sensitivity might explain vulnerability to OUD among patients receiving opioids for chronic pain. A secondary hypothesis was that pain catastrophizing might mediate these differences.

• Pain sensitivity was measured in 20 patients receiving chronic opioid therapy who had not developed signs or symptoms of OUD after at least 18 months of opioid treatment, and in 20 patients who developed OUD while taking prescription opioids and were being treated with buprenorphine.
• Patients without a diagnosis of OUD reported higher baseline pain intensity scores and were taking full agonist opioids rather than buprenorphine.
• Those who developed OUD showed increased sensitivity to a heat test of central sensitization, but not to a cold pressor test. For both tests, those who developed OUD subjectively rated the maximal intensity of pain higher than those not developing OUD.
• Scores measuring pain catastrophizing were not different between the 2 groups and did not mediate differences in pain sensitivity.

Comments: Some measures of pain sensitivity were increased in patients who developed OUD during opioid treatment for chronic pain and were being treated with buprenorphine. While these differences could be due to pre-existing pain sensitivity putting patients at risk of OUD, other possible explanations include differences in current pain severity, current medication use (buprenorphine versus full agonists), or the increased pain sensitivity might be a complication of OUD. Prospective assessment of patients initiating opioids for chronic pain would be necessary to assess the predictive power of pain sensitivity as a risk factor for OUD in this population.

Joseph Merrill, MD, MPH

Reference: Compton PA, Wasser T, Cheatle MD. Increased experimental pain sensitivity in chronic pain patients who developed opioid use disorder. Clin J Pain. 2020;36:667-674.