Validation of Self-Report Pain Scales in Children

BACKGROUND AND OBJECTIVES: The Faces Pain Scale-Revised (FPS-R) and Color Analog Scale (CAS) are self-report pain scales commonly used in children but insufficiently validated in the emergency department setting. Our objectives were to determine the psychometric properties (convergent validity, discriminative validity, responsivity, and reliability) of the FPS-R and CAS, and to determine whether degree of validity varied based on age, sex, and ethnicity. METHODS: We conducted a prospective, observational study of English- and Spanish-speaking children ages 4 to 17 years. Children with painful conditions indicated their pain severity on the FPS-R and CAS before and 30 minutes after analgesia. We assessed convergent validity (Pearson correlations, Bland-Altman method), discriminative validity (comparing pain scores in children with pain against those without pain), responsivity (comparing pain scores pre- and postanalgesia), and reliability (Pearson correlations, repeatability coefficient). RESULTS: Of 620 patients analyzed, mean age was 9.2 +/- 3.8 years, 291 (46.8%) children were girls, 341(55%) were Hispanic, and 313(50.5%) were in the younger age group (<8 years). Pearson correlation was 0.85, with higher correlation in older children and girls. Lower convergent validity was noted in children <7 years of age. All subgroups based on age, sex, and ethnicity demonstrated discriminative validity and responsivity for both scales. Reliability was acceptable for both the FPS-R and CAS. CONCLUSIONS: The FPS-R and CAS overall demonstrate strong psychometric properties in children ages 4 to 17 years, and between subgroups based on age, sex, and ethnicity. Convergent validity was questionable in children <7 years old.