The Objective Stretch Marks photo-numerical Assessment Scale (OSMAS): a new and complete method to assess Striae Distensae

Introduction: Striae distensae (SD) evaluation criteria have been recently described, but none is focused on objective striae assessment. With the purpose of better and objectively estimate the SD severity, the Objective Stretch Marks Assessment Scale (OSMAS) has been developed by our team. Material and methods: Seven hundred Caucasian patients were included in the study and assessed. To assess SD severity the abdomen, breasts, hips, gluteal area, back area, thighs, calves and upper limbs photonumeric grading scales were developed. The Rasch model was used as part of the validation process. A score was attributed to each patient, based on the scales we developed. The inter-rater reliability and test-retest reliability were analysed. Results: Eight photo-numerical scales for SDs treatment outcomes assessment were developed. All scales exceeded criteria for acceptability, reliability and validity. The inter and intra-rater reliabilities were good with a substantial or virtually perfect inter-rater reliability for the total score (p=0.16). Conclusion: Our results allowed us to validate the OSMAS as a reliable and reproducible tool to assess SD treatment outcomes. This scale could be also considered as an important new metrics that can be used in clinical research.