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.