Psychometric Properties of a Modified Version of the Faces Pain Scale-Revised (Modified FPS-R) to Evaluate Worst Pain in Children and Adolescents With Sickle Cell Anemia.

We evaluated psychometric properties (validity, reliability, and responsiveness) of a modified Faces Pain Scale-Revised (FPS-R) in 257 patients with sickle cell anemia (SCA) 7 to below 18 years old in a randomized, multinational clinical study. The modified FPS-R asks patients to report, by daily diary, their worst intraday SCA-related pain. Intraclass correlation coefficient assessed test-retest reliability between month 1 and month 2. Pearson correlations between monthly mean SCA-related pain intensity, activity interference score, analgesic use, and opioid use assessed convergent validity. Responsiveness was assessed with correlations of changes of monthly pain rate or intensity and changes in analgesic use or activity interference score from month 1 to month 9. Intraclass correlation coefficients for pain intensity and pain rate were 0.777 and 0.820, respectively, indicating agreement among stable patients. Moderate associations were shown between mean pain intensity and analgesic use (r=0.39) and opioid use (r=0.44), and between monthly pain rate and analgesic use (r=0.38). Moderate-to-large associations were observed between change in mean pain rate or intensity and changes in analgesic use (r=0.38 to 0.39, both P<0.001) and in activity interference scores (r=0.82 to 0.92, both P<0.001). These results support use of the modified FPS-R across cultures in children and adolescents aged 7 to below 18 years with SCA.