Development and Verification of a New Method for Evaluating Facial Expressions Based on the Premature Infant Pain Profile-Revised

Introduction: Managing neonatal pain through appropriate pain assessment is crucial. The use of reliable, validated, and multidimensional tools for pain evaluation has been recommended. However, these tools have not yet gained widespread use in Japan due to their complexity, which involves numerous evaluation and observation items, making thorough observation challenging. Methods: We developed a new method based on the premature infant pain profile-revised (PIPP-R), a multidimensional evaluation tool that includes physiological and behavioral indicators, to simplify the evaluation of facial expressions. Instead of assessing three facial expressions individually, we evaluate them in four categories. We also created a system that automatically records changes in vital signs and calculates scores. In this study, we determined if the facial expression score aligns with the conventional PIPP-R-based facial expression score. The scoring methods were categorized into three types: (1) a real-time new method, where facial expressions were evaluated concurrently with the puncture procedure using a new method; (2) an individual assessment method using recorded videos from the puncture sessions with facial expressions scored later using the PIPP-R; and (3) a new video-based method, in which facial expressions were evaluated using the new method while watching recorded videos. Results: The study included 63 healthy neonates (born at ≥37 weeks’ gestation) delivered at our hospital. The degree of agreement among the methods and the inter-rater agreement were analyzed. Both showed high levels of consistency. Conclusion: The facial expression scores obtained using the new method are equivalent to those of the PIPP-R and can be used for real-time assessment of pain intensity in full-term neonates. Simplifying the evaluation process has the potential to improve clinical practice and will be further investigated in future studies.