The Wong-Baker pain FACES scale measures pain, not fear

The Wong-Baker FACES pain rating scale (WBS) is preferred by parents and patients for reporting pain severity. However, it is speculated that the "no hurt" and "hurts worst" anchors confound pain measurement with nonnociceptive states. The objective of our study was to determine if fear confounds reporting of pain severity on the WBS. We hypothesized that the WBS would correlate with a psychometrically different pain severity scale (the visual analog scale [VAS]) and not correlate with a fear measure, the Child Medical Fear Scale (CMFS).

This was a prospective observational study of children 7 to 12 years presenting to a university-based suburban pediatric ED with acute pain. Patients rated pain severity on the WBS ordinal scale and a 100-mm unhatched VAS with marked end points of "no pain" and "worse pain ever." Patients also completed a 26-item CMFS. Correlations between the WBS and VAS with the CMFS total score were assessed with Spearman correlation and exploratory factor analysis.

All 3 scales were completed in 197 children. Correlation between the severity scales (WBS-VAS) was moderate: 0.63 (95% confidence interval [CI], 0.54-0.71). However, correlations between the WBS-CMFS and VAS-CMFS were poor: -0.02 (95% CI, -0.16 to -0.12) and 0.01 (95% CI, -0.13 to 0.15), respectively. Correlations did not differ by sex, grade, pain location, or cause of pain (traumatic vs atraumatic). Exploratory factor analysis demonstrated excellent loadings within 2 factors: pain and fear.

The WBS demonstrates moderate correlation with another measure of pain (VAS) and is not mistaken for fear among school-aged patients presenting to the ED with pain.