Classification of chronic pain associated with spinal cord injuries

Abstract

Objectives: To determine interrater reliability of a classification system for chronic pain in persons with spinal cord injury (SCI) and to determine the frequency and characteristics of various pain types as categorized by this system.

Design: Independent categorization (based on questionnaires; for 15 persons, questionnaires plus personal interviews) by 2 investigators.

Setting: Community.

Participants: A total of 163 individuals aged >or=18 years with SCI and pain.

Interventions: Not applicable.

Main outcome measures: Pain categories, Short-Form McGill Pain Questionnaire, and Chronic Pain Grade questionnaire.

Results: Among 41 (25%) questionnaires categorized independently by 2 investigators, strength of agreement in categorizing 68 pain problems was substantial (kappa=.68). For 15 persons whose pain was categorized in person by 2 investigators, strength of agreement was also substantial (kappa=.66). Among 163 survey respondents with pain, the most common worst pain was SCI pain (31.9%). Mean characteristic pain intensity +/- standard deviation for worst pain, regardless of type, was 61.02+/-18.5 on a scale from 0 to 100. On average, for worst pain, respondents reported moderate pain-related disability (43.70+/-29.4; scale range, 0-100). Although certain pain descriptors were more often associated with a specific type of pain, none was pathognomonic.

Conclusions: Substantial interrater reliability was achieved in determining pain categories by use of responses to a questionnaire with a classification system based on presumed pathology. Adding interviews with patients increased our ability to classify pain but did not improve overall interrater reliability.