Validation of the Wong-Baker FACES Pain Rating Scale in pediatric emergency department patients

Objectives: The Wong-Baker FACES Pain Rating Scale (WBS), used in children to rate pain severity, has been validated outside the emergency department (ED), mostly for chronic pain. The authors validated the WBS in children presenting to the ED with pain by identifying a corresponding mean value of the visual analog scale (VAS) for each face of the WBS and determined the relationship between the WBS and VAS. The hypothesis was that the pain severity ratings on the WBS would be highly correlated (Spearman's rho > 0.80) with those on a VAS.

Methods: This was a prospective, observational study of children ages 8-17 years with pain presenting to a suburban, academic pediatric ED. Children rated their pain severity on a six-item ordinal faces scale (WBS) from none to worst and a 100-mm VAS from least to most. Analysis of variance (ANOVA) was used to compare mean VAS scores across the six ordinal categories. Spearman's correlation (rho) was used to measure agreement between the continuous and ordinal scales.

Results: A total of 120 patients were assessed: the median age was 13 years (interquartile range [IQR] = 10-15 years), 50% were female, 78% were white, and six patients (5%) used a language other than English at home. The most commonly specified locations of pain were extremity (37%), abdomen (19%), and back/neck (11%). The mean VAS increased uniformly across WBS categories in increments of about 17 mm. ANOVA demonstrated significant differences in mean VAS across face groups. Post hoc testing demonstrated that each mean VAS was significantly different from every other mean VAS. Agreement between the WBS and VAS was excellent (rho = 0.90; 95% confidence interval [CI] = 0.86 to 0.93). There was no association between age, sex, or pain location with either pain score.

Conclusions: The VAS was found to have an excellent correlation in older children with acute pain in the ED and had a uniformly increasing relationship with WBS. This finding has implications for research on pain management using the WBS as an assessment tool.