The Patient and Observer Scar Assessment Scale

The POSAS is a reliable and valid scar assessment scale that measures scar quality from two perspectives: the patient and the clinician. The POSAS measures scar quality in all types of scars and can be used in clinical and research settings.



The POSAS can be used free of charge by researchers without commercial interest. We do, however, request a fee for commercial use of the POSAS (i.e. involvement of a manufacturer/supplier in the study) in order to maintain the POSAS website and continue the development of the POSAS.

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.

From: A review of scar assessment scales,

Tuyet A Nguyen et al. Seminars in Cutaneous Medicine and Surgery, Vol. 34, March 2015


Learn more about scar formation and outcome measurements

Which (type of) outcome measurement instruments are being used to measure scar quality?

Measurements of scar quality can be performed by different types of outcome measurement instruments, including measurement devices and scar assessment scales. Measurement devices are machines which usually measure one characteristic of scar quality. Scar assessment scales allow for the evaluation of multiple characteristics of scar quality.

How do scars form?

A scar is an undesirable, yet normal consequence of wound healing. To understand how they are formed, it’s key to understand a little bit about the skin and how it heals after damage. If a wound extends deep into the dermis or even the subcutaneous tissue below that, it results in more severe scars. It is the result of skin wound healing, a complex process consisting of three phases.