Comparative reliability and validity of chronic pain intensity measures

Reliable and valid measures of pain are essential for conducting research o n chronic pain. The purpose of this longitudinal study was to compare the r eliability and validity of several measures of pain intensity. One hundred twenty-three patients with chronic pain were administered telephone intervi ew versions of 0-10 scales of current, worst, least and average pain, immed iately prior to beginning a multidisciplinary treatment program, The measur es were administered again to these subjects 2 weeks (n = 108), 1 month (n = 106) and 2 months (n = 105) after the end of treatment. The validity (def ined as ability to detect changes in pain intensity over the course of trea tment up to the 2-month follow-up assessment) and reliability (defined as s tability over time in the 2 months after treatment) of these four measures and of composite combinations of these measures were examined. Contrary to prediction, the composite measures did not show a statistically significant superiority to the individual ratings in terms of their ability to detect change in pain intensity from pre-treatment to various points after treatme nt. The composite scores did, however, show greater stability than did the individual ratings after treatment. The practical conclusions of this study are; (1), individual 0-10 pain intensity ratings have sufficient psychomet ric strengths to be used in chronic pain research, especially research that involves group comparison designs with relatively large sample sizes, but, (2), composites of 0-10 ratings may be more useful when maximal reliabilit y is necessary, (e.g. in studies with relatively small sample sizes, or in clinical settings where monitoring of changes in pain intensity in individu als is needed). (C) 1999 International Association for the Study of Pain. P ublished by Elsevier Science B.V.