Background. There is no universally accepted system to accurately predict complexity of cancer pain management. The Edmonton Classification System for Cancer Pain (ECS-CP) was developed from the Edmonton Staging System (ESS) for Cancer Pain (1989) and the revised ESS (rESS) (2005). This study is an extension of an international multicenter validation study of the ECS-CP.
Research objectives. The primary objective was to estimate the reliability of ratings for the five ECS-CP features (ie, pain mechanism, incident pain, psychological distress, addictive behavior, cognitive function) using different raters across diverse palliative care services.
Methods. Eleven-hundred patients were recruited from 11 specialist palliative care sites (inpatient and outpatient palliative consult services, tertiary palliative care units, hospice settings) located in Canada, USA, Ireland, Israel, Australia and New Zealand (100 per site). A palliative care specialist completed the ECS-CP for each referred cancer patient. Additional information, including daily patient pain ratings, was recorded until study endpoint (ie, stable pain control, discharge, death). At six sites, two raters independently completed the pain classification system within 24 hours of each other (n = 338). Intra-class correlations were used to calculate interrater reliability estimates across all sites.
Results. 944/1100 patients had a pain syndrome (86%); 338/944 (36%) involved two independent raters. Interrater reliability estimates, in descending order, were: pain mechanism 0.81 (95% CI .77–.84), cognitive function 0.72 (95% CI .66-.77), incident pain 0.67 (95% CI .61-.72), addictive behavior, 0.64 (95% CI .57-.70) and psychological distress 0.52 (95% CI .44-.59). Comparisons between these estimates and interrater reliability estimates from a previous ECS-CP validation study will be presented.
Conclusion. The variability across raters, particularly for incident pain, addictive behavior and psychological distress, highlight the complexity of assessing these features.