To examine the clinical significance of changes in chronic pain in 2 disability groups: spinal cord injury and lower limb amputation.
A reanalysis of 2 controlled clinical trials for pain in persons with disabilities. Eighty-two persons with spinal cord injuries and 34 persons with amputations provided pretreatment and posttreatment ratings of pain intensity on 0 to 10 numerical rating scales. After treatment, participants also rated the meaningfulness of any changes in pain they experienced.
An average decrease of 1.80 points on the 0 to 10 numerical rating scales and percent decreases of about 36% corresponded to reports of a meaningful change in pain. There was no significant difference between samples, and also no differences due to gender or treatment condition. Age and pretreatment pain, however, were associated with the amount of pain decrease rated as meaningful. The change in pain intensity rated as meaningful was greater for older participants and participants with higher levels of pretreatment pain. Consistent with previous research, percent change scores were less biased by pretreatment pain than were absolute change scores.
These findings are generally consistent with similar findings in other pain populations, and, in light of previous research, support an approximate 33% decrease in pain as a reasonable standard for meaningful change across chronic pain conditions. Percent change scores may be more useful for comparing the effects of pain treatments across samples or conditions because they are less biased by pretreatment pain level.