The introduction of the Patient and Observer Scar Assessment Scale (POSAS) in 2004 was a turning point in the assessment of scars through the use of scales. The POSAS was the first scale to take into account both the patient and provider perspective, including both a Patient Scar Assessment Scale (P-SAS) and an Observer Scar Assessment Scale (O-SAS).
From: A review of scar assessment scales,
Tuyet A Nguyen et al. Seminars in Cutaneous Medicine and Surgery, Vol. 34, March 2015