Central Sensitization May Connect Opioid Use Disorder and Chronic Pain

As published in Pain Reports, central sensitization may be the connection between opioid use disorder (OUD) and chronic pain. Individuals with more central sensitization experienced more pain compared with those with less central sensitization. 

“Our study is the first to give patients with OUD a scale that measures central sensitization,” said Dr. O. Trent Hall, lead author of the study and an addiction medicine physician in Ohio State’s Department of Psychiatry and Behavioral Health. “Our study provides the first evidence of central sensitization underlying the chronic pain and OUD relationship and demonstrates a new tool for easily measuring central sensitization among individuals with OUD.” 

In a one-of-a-kind study, 141 participants were enrolled from an addiction treatment center and took the American College of Rheumatology 2011 Fibromyalgia Survey (ACR-FMS) digitally. The mean score for pain and symptom severity on the ACR-FMS was 9.88 ± 4.91 (range, 0-23 of 28 possible), and had a normal distribution on the Shapiro–Wilk test (P>.05). In the study, 88.7% of participants reported at least 1 painful body region with an average of 3.27 ± 2.83. Low back (99, 70.2%), neck (45, 31.9%), and upper back (43, 30.5%) areas were the most commonly reported sites of pain. 

The survey had questions about pain interference, quality of life and items regarding pain-beliefs, and expectations of pain and addiction treatment. Participants were more likely to have pain interference with median scores of 39 of 70 on the brief pain inventory (BPI) pain interference subscale, 24 of 40 for affective interference, and 14 of 30 for interference with activity.

Median health-related quality of life was 50 or less in 7 of 8 life domains: bodily pain 45 (IQR = 33–68), general health 45 (IQR = 35–60), mental health 48 (IQR = 36–59), social functioning 50 (IQR = 25–63), vitality 40 (IQR = 30–50), role limitations due to physical health 50 (IQR = 3–100), and role limitations due to emotional problems 0 (IQR = 0–67). 
The sample median of physical function was 75 (IQR = 45–90).

More than half of the participants (61%) agreed or strongly agreed that they first used opioids because they felt pain. About half of the participants (54.6%) expressed the pain was a main factor maintaining their addiction. A little over half of participants (59.6%) confirmed the pain-coping motivated their escalating use of opioid, but less than half (48.2%) were aware that opioid use could make the pain worse

“Additionally, patients higher in central sensitization were more likely to report pain as a major reason for why their opioid addiction first began, as well as for putting off addiction treatment, continuing and increasing their use of opioids, and fear of pain causing OUD relapse in the future,” said senior author Dr. Daniel J. Clauw, director of the Chronic Pain and Fatigue Research Center at the University of Michigan.