A prospective multicenter assessment of the Edmonton staging system for cancer pain.

Two hundred and seventy-seven patients were admitted to this prospective multicenter study in order to assess the accuracy of a staging system for cancer pain. The staging system (SS) was completed by a trained physician during the initial consultation. This system included the assessment of pain mechanism (PM, neuropathic versus nonneuropathic), pain characteristic (PC, continuous versus incidental), previous opioid dose (OD), cognitive function (CF), psychological distress (PD), tolerance (T), past history of alcohol or drugs (A). During day 21, a final assessment of pain control was made. Agreement for staging was observed in 96% of cases for investigators 1 and 2 (kappa 0.76, P < 0.001), and in 84% of cases between investigators 1 and 3 (kappa 0.723, P < 0.001). Of 276 evaluable patients, 86/92 Stage I (good prognosis) patients achieved good PC (93%) versus 102/184 Stage II and III (poor prognosis) patients (55%, P < 0.001). Sensitivity and specificity of the system were found to be 0.93 and 0.46, respectively. Univariate correlation found significant correlation between pain control and all variables except CF. In logistic regression, CF and OD showed no significant correlation. We, therefore, propose a more simple SS of five categories (PM, PC, PD, T, and A) and two stages (good and poor prognosis). We conclude that the SS is highly accurate in predicting patients with good prognosis, but patients with "poor prognosis" can still achieve good pain control in more than 50% of cases.