Internal Opioid System Predicts NSAID Tx Response for Neuropathic Pain
According to study results presented at the 30th Annual Meeting of the American Academy of Pain Medicine, scientists can predict who will respond to NSAID treatment by assessing the nervous system's own capacity to regulate pain.
Patients whose tests had showed superior conditioned pain modulation (CPM) had less pain and fewer neuropathic symptoms by the end of treatment. CPM is an index of endogenous pain-inhibitory capacity calculated from quantitative sensory testing (QST) measurements. A higher CPM indicates better functioning endogenous pain-inhibitory systems.
Study investigators conducted a 5-week efficacy study of diclofenac topical gel, an NSAID, in patients with knee osteoarthritis (n=44). Assessment methods included the use of Neuropathic Pain Questionnaire (NPQ), the Knee Injury and Osteoarthritis Outcome Score (KOOS), an exercise performance task and QST. Data showed a 30% improvement in pain on average and significant response for neuropathic symptoms (P<0.01) and improved function (self-rated and measured; P<0.01) by the end of 4 weeks.
Investigators were able to correctly predict changes in pain intensity and neuropathic symptoms using CPM (P<0.05). Patients with higher baseline CPM reported lower pain intensity and neuropathic pain symptoms by the end of the study (P<0.05).
Researchers added that factors such as past memories, stress, anxiety, distraction or attention can alter the pain experience thus further suggesting the presence of endogenous pain modulatory systems.
For more information visit the American Academy of Pain Medicine website.