User instructions POSAS 2.0

User instructions POSAS 2.0

10-point score

Each item of the POSAS is rated on a 10-point score. The lowest score is ‘1’, which corresponds to the situation of normal skin (i.e. normal pigmentation, no itching). Score 10 equals the largest difference from normal skin (i.e. the worst imaginable scar or sensation).

The total score of both scales can be simply calculated by summing up the scores of each of the six items. The total score can range from 6 to 60. The overall opinion item is not included in the sum score.

Observer and patient scales

The POSAS 2.0 measures scar quality and consists of two parts: the Patient Scale and the Observer Scale. Both scales contain six items of scar quality.

Patient scale

The Patient scale includes the following items:

Observer scale

The Observer scale includes the following items. Each item includes category boxes. The categories are for descriptive purposes only, and are not included in calculating the total score of the POSAS.

Frequently asked questions

What area of the scar should be assessed using the POSAS?

The different strategies include:

  • scoring the scar on average
  • scoring the worst part of the scar (in terms of complaints or visually)

In general, the best strategy depends on the research or clinical question. This should be discussed at the start of your project, or before you start using the POSAS in the clinic, to make sure that the same scar area is assessed. It is also important for observers and patients to score the same scar area.

What is the difference between the POSAS 2.0 and POSAS 3.0?

The main reasons for the initiation of the project to develop the POSAS 3.0, was the lack of input by patients and international professionals in the development of the POSAS 2.0. This third POSAS version is developed to measure scar quality in patients with all types of scars, including those caused by burns, necrotizing fasciitis, acne, trauma, or surgery. The Patient Scale has been developed using a series of focus group meetings that took place in the Netherlands and Australia. The Observer Scale has been developed using a systematic method to reach consensus among experts. The POSAS 3.0 contains more items to gain deeper insight in scar quality.

I am currently using the POSAS 2.0. Should I switch to the POSAS 3.0?

As explained above, the POSAS 3.0 has been developed with patients and international professionals in the field of scar quality and measurement. The POSAS 2.0 will still be available until one year after the launch of the POSAS 3.0. It is recommended to use the POSAS 3.0.

I have a license for the POSAS 2.0 and want to switch to POSAS 3.0. Do I need to apply for a new license?

If you would like to use the POSAS 3.0, please apply for a new license. If you currently have a commercial license, please contact us for further information.

What paper(s) should I use as a reference when mentioning the POSAS in my study?

For the use of the POSAS 2.0 the following article must be referenced: van de Kar AL, Corion LU, Smeulders MJ et al. Reliable and feasible evaluation of linear scars by the patient and observer scar assessment scale. Plastic Reconstructive Surgery. 2005;116:514-522

Is the POSAS available in languages other than English?
Yes, a list of all the available languages can be found on the page About POSAS.
Can I translate the POSAS at my institution into an additional language?

The POSAS 2.0 can be translated by researchers. The POSAS 3.0 can only be translated by certified translation agencies. For permission regarding the translation of the POSAS, please contact us via the contact form.

Do I need a license agreement if I want to use the POSAS?

Yes, as of May 2020 a license agreement is mandatory for both the POSAS 2.0 and 3.0. Request a license.

Do I need to pay a fee for the use of the POSAS?

Yes, we request a small fee for the commercial use of the POSAS by or on behalf of a pharmaceutical company, medical device manufacturer or any other for-profit stakeholder. Fees apply for research or non-research purposes. This compensation will be used to maintain the POSAS website and continue the development of the POSAS. Read more about licensing.

Can we incorporate the POSAS within application software?

Yes, this is possible. An annual subscription-based license agreement grants the rights for digital use of the POSAS.

Is the POSAS validated for measurements in children?

Although the POSAS was not developed for scar quality measurements in children, we believe that the adult POSAS version would be acceptable for use within adolescents (15 years and older). However, future studies must be undertaken in order to validate this hypothesis. The next step of the POSAS research team is to develop a POSAS-kids version, enabling reliable and valid scar quality measurements in young children.

Can parents be used as a proxy if children are too young to complete the POSAS independently?

No, we do not encourage using parents as a proxy if children are too young to complete the POSAS independently. The next step of the POSAS research team is to develop a POSAS-kids version, enabling reliable and valid scar quality measurements in young children.

Do you have data/information supporting what change in POSAS score reflects a minimal (clinically) important difference (M(C)ID)?

Unfortunately, the M(C)ID of the POSAS 2.0 has not been established yet. Currently, various measurement properties of the POSAS 3.0, including the M(C)ID, are being evaluated using an international field test study.

Which types of scars are suitable for POSAS measurements?

The POSAS 2.0 was initially developed for burn scars, but has been validated over the years for multiple other types of scars. The POSAS 3.0 has been developed for all types of scars, such as scars caused by burns, surgery, trauma, acne, as well as keloids.

Can the POSAS be used if there is no reference area of healthy skin available for comparison, for example in extensive burn scars?

POSAS measurements may be less valid in this case, because some of the included scar characteristics are rated based on the extent to which they differ from the patient’s normal skin.

Should I use the sum score or the items? And does the sum of the patient and observer scale mean anything?

The construct of the POSAS (i.e. what it aims to measure) is scar quality. Scar quality is formed by the scar characteristics included as items in the POSAS. Therefore, if the aim is to evaluate scar quality, the sum score must always be used.

The Patient Scale and the Observer Scale are two separate instruments that measure quality from different perspectives, and, therefore, are complementary to each other. The sum score of both instruments provides no additional meaning.