Postoperative pain trajectories in chronic pain patients undergoing surgery: the effects of chronic opioid pharmacotherapy on acute pain.

UNLABELLED: For 2 weeks following surgery, 55 patients with preexisting chronic pain (CP) reported daily postoperative pain with movement and at rest. Of these, 30 CP patients used opioid pharmacotherapy for CP management and 25 did not. We modeled pain resolution in each patient using a linear fit so that each patient yielded 2 scores for each pain rating: 1) an intercept, or initial level of pain, immediately after surgery; and 2) a slope, or rate of pain resolution. The patients not using opioid pharmacotherapy had a mean pain with movement intercept of 5.4 and a slope of -.20, while the patients using opioid pharmacotherapy had a significantly higher mean intercept of 7.68 (P = .001) and a slope of -.21, sustaining higher pain levels over days. The opioid pharmacotherapy patients had the same rate of pain resolution as the other CP patients, and both groups resolved their pain more slowly than normal surgery patients. Preexisting CP may predispose a patient undergoing surgery to a slower rate of postoperative pain resolution. Chronic pain patients who use opioids share this predisposition but in addition, they are at risk for markedly higher postoperative pain across the entire pain resolution trajectory. PERSPECTIVE: This is an observational rather than a randomized controlled study, and as such is less definitive. Nonetheless, these findings are consistent with those of animal studies showing that prolonged exposure to opioids can produce opioid-induced hyperalgesia. Patients with opioid pharmacotherapy for chronic pain who undergo surgery merit special attention for acute pain management.