Reliability and validity of individual and composite recall pain measures in patients with cancer.

Objectives: To evaluate and compare the validity and reliability of individual and composite recall pain intensity measures.

Design: Secondary analyses using data from a published 14-day open-label crossover clinical trial comparing two active treatments.

Setting: Multiple settings.

Participants: Fifty-two adults with a history of chronic cancer pain.

Measures: Recall ratings of least, worst, and average pain during the past 2 days; composite score representing recalled characteristic pain in the past 2 days; and daily diary ratings of pain intensity from which "actual" least, worst, and average pain scores were derived.

Results: Recall ratings of least and average pain, and a composite score representing recalled characteristic pain were accurate (differed no more than three points from "actual" scores on a 0-100 scale). Although the recall rating of worst pain significantly (P < 0.05) overestimated actual worst pain, the differences were minor (i.e., seven to eight points on a 0-100 scale). All of the recall measures demonstrated validity via their strong associations with the measures of actual pain intensity. The recall measures also demonstrated excellent test-retest stability, although the diary-derived measures tended to be more stable than the recall measures did. The composite measure of recalled characteristic pain demonstrated a high level of internal consistency (Cronbach's α = 0.90).

Conclusions: Individual recall ratings and a composite score representing recalled characteristic pain intensity are reliable and valid measures of actual pain in patients with cancer. The findings support their use as outcome measures in clinical trials.