Facial expressions of pain in daily clinical practice to assess postoperative pain in children: Reliability and validity of the facial action summary score.

BACKGROUND: Behavioural pain scales are recommended to assess postoperative pain for children who are too young to use self-report tools. Their main limitation is underestimation of pain in the days following an intervention. Although relevant, facial expression is not used in daily clinical practice. This prospective study aimed to assess the validity and reliability of the Facial Action Summary Score (FASS), a five-item scale, to assess postoperative pain until hospital discharge in children <7 years. METHODS: Assessments of pain and anxiety of 123 children using FASS and validated scales were used to study the psychometric validity of the FASS in clinical practice. RESULTS: The content validity was previously investigated in a development study. The internal validity of the FASS was high with excellent reliability (intraclass coefficient = 0.94) and a high Cronbach α (0.89). Convergent validity with pain scales (FLACC [Face, Legs, Activity, Cry, Consoling] and FPS-R [Faces Pain Scale - Revised]) was high (r > 0.8). Sensitivity to change was verified by a significant decrease in the score after rescue analgesia. For a threshold of 2/5, the FASS shows excellent specificity (97%) and sensitivity (82%). The low number of false negatives is the main strength of this tool. CONCLUSIONS: This work highlights the interest in using facial expression in daily clinical practice to manage postoperative pain. The FASS is easy to use with excellent psychometric properties and is particularly sensitive to measure pain in the days following surgery. SIGNIFICANCE: The aim of this study was to prove that facial expression of pain can be used in clinical practice to measure postoperative pain in children. The reduced number of false negatives is the main strength of this tool.

A prospective comparison of post-surgical behavioral pain scales in preschoolers highlighting the risk of false evaluations.

Four behavioral rating scales (BRS) (CHEOPS, CHIPPS, FLACC and OPS) assessing postoperative pain in children aged 1-7 years were studied to compare their psychometric properties, sensitivity and specificity. One hundred and fifty children included in this prospective longitudinal study were videotaped to analyze retrospectively peri-operative behaviors. Pain and anxiety were evaluated by children or by their parents prospectively. At the end of the study, four observers rated the peri-operative videos using the four BRS. Because self-reporting cannot be used for all the children, facial expression of pain was analyzed from the videos to create a Facial Action Summary Score (FASS) which was considered as a reference for the study of validity of the four BRS. Internal validities were excellent but external validities were mixed. The FLACC seems to be better adapted to assess post-surgical pain in children between 1 and 7 years old. Nevertheless, it was significantly correlated with anxiety measures. Moreover, the analysis of sensitivity and specificity using both self-reporting of pain and FASS showed that some children were still under-evaluated. The multivariate analysis underlines silence as a high risk factor of misevaluating postoperative pain. In conclusion, this study highlights the difficulty of discriminating pain intensity from anxiety when using the four BRS and that postoperatively, nearly one child in 10 was misevaluated.