Defining No Pain, Mild, Moderate, and Severe Pain Based on the Faces Pain Scale-Revised and Color Analog Scale in Children With Acute Pain.

Objectives: The aims of this study were to define the Faces Pain Scale-Revised (FPS-R) and Color Analog Scale (CAS) scores associated with no pain, mild pain, moderate pain, and severe pain in children with acute pain, and to identify differences based on age, sex, and ethnicity.

Methods: We conducted a prospective observational study in 2 pediatric emergency departments of children aged 4 to 17 years with painful and nonpainful conditions. We assessed their pain intensity using the FPS-R, CAS, and qualitative measures. Pain score cut points that best differentiated adjacent categories of pain were identified using a receiver operating characteristic-based method. Cut points were compared within subgroups based on age, sex, and ethnicity.

Results: We enrolled 620 patients, of whom 314 had painful conditions. The mean age was 9.2 years; 315 (50.8%) were in the younger age group (aged 4-7 years); 291 (46.8%) were female; and 341 (55%) were Hispanic. The scores best representing categories of pain for the FPS-R were as follows: no pain, 0 and 2; mild pain, 4; moderate pain, 6; and severe pain, 8 and 10. For the CAS, these were 0 to 1, 1.25 to 2.75, 3 to 5.75, and 6 to 10, respectively. Children with no pain frequently reported nonzero pain scores. There was considerable overlap of scores associated with mild and moderate pain. There were no clinically meaningful differences of scores representing each category of pain based on age, ethnicity, and race.

Conclusions: We defined pain scores for the FPS-R and CAS associated with categories of pain intensity in children with acute pain that are generalizable across subgroups based on patient characteristics. There were minor but potentially important differences in pain scores used to delineate categories of pain intensity compared to prior convention.