Should the rate of opioid dose escalation be included as a feature in a cancer pain classification system?

ABSTRACT

The purpose of this study was to assess the need for opioid dose escalation as a feature of a pain classification system for advanced cancer patients. Opioid dose escalation was included as a prognostic feature in the original Edmonton Staging System (ESS) for pain classification, but was not included among the five features of the revised ESS (rESS) pain mechanism, incident pain, psychological distress, addictive behavior, and cognitive function. Mercadante et al.'s definition of opioid escalation index percentage (OEI%) has been used as a surrogate marker for opioid responsiveness. Our hypothesis was that younger age (<60 years), neuropathic pain, incident pain, psychological distress, and addictive behavior would be associated with an OEI% >5%. Using data from a recent multicenter validation study of the rESS, a secondary analysis of a subsample of 532 advanced cancer patients with a pain syndrome was conducted. Approximately 44% (n=232) of the patients had an OEI% >5%. There were no significant associations between OEI% and age, neuropathic pain, incident pain, psychological distress, or addictive behavior. As originally proposed as a clinical marker, the OEI% may oversimplify the complexity of pain management in advanced cancer patients. Future studies are required to better elucidate the need for opioid dose escalation as a feature of a cancer pain classification system.