Introduction: Review of the literature reveals the difficulty in comparing research results of analgesic management for cancer pain. Oncologists use the tumor, nodes, metastases (TNM) system. The need for a classification system for cancer pain prompted the development of the Edmonton Staging System (ESS). There are problems with both the terminology and definitions of the ESS. A revised ESS (rESS) was designed and a multi-centre study conducted to determine reliability and predictive value.
Methods: The rESS includes mechanism of pain, presence/absence of incidental pain, presence/absence of psychological distress and addictive behavior, and cognitive function. The rESS hypothesis is that patients (pts) with less problematic pain syndromes will require shorter time to achieve stable pain control, less complicated analgesic regimes, be more responsive to opioid therapy and use lower opioid doses.
Results: The study included 746 pts with 619 having a pain syndrome. Interrater reliability scores ranged from 0.67 for pain mechanism to 0.95 for presence of addiction. Pts with neuropathic pain, incidental pain, psychological distress or psychological distress and addiction, required a longer time to achieve stable pain control (pB/0.05). Impaired cognitive function shortened the time required to achieve stable pain control (pB/0.05). Pts with neuropathic or incidental pain used more modalities to achieve stable pain control (pB/0.01). Pts with neuropathic pain, incidental pain, presence of psychological distress or addiction required a higher final mean equivalent daily dose of morphine (MEDD) (pB/0.001).
Conclusion: This study provides some initial positive data on reliability and validity. As noted with the TNM, a final definitive version may prove ellusive due to advances in knowledge of prognostic factors, diagnosis and treatment.