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.
Not suitable for photographic assessment
The POSAS is not suitable for photographic evaluation, as some of the characteristics are impossible to evaluate on the basis of photographs alone. For example, palpation of the skin is necessary to provide a sound assessment.
Frequently asked questions
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
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 using the contact form.
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.
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.
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.
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.
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.
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.
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:
Pain
Pain is defined as an unpleasant sensory and emotional experience. Although not often reported, pain caused by scars can be very invalidating if present. The pathophysiology is still not well understood, but a strong relation with scar hypertrophy and itching has been reported.
Itch
Itching is an irritating cutaneous sensation that produces a desire to scratch, which has a large impact on the quality of life. Itching is often present when large body surface areas are involved (i.e. after extensive burn injuries or paediatric burn injury) and is associated with hypertrophic scarring.
Thickness
Scar tissue normally becomes thicker than the surrounding skin (hypertrophy) during the first months after which the thickness reduces in most cases. Burn scars frequently remain hypertrophic to some extent but scar atrophy is also noted in some scar categories.
Color
The color difference between the scar and healthy surrounding skin, which is caused by an altered vascularization and pigmentation.
Stiffness
Scar tissue can be hard and firm as a result of collagen reorganization after injury. Stiffness of the scar tissue may cause a tight feeling and functional impairment, especially when scars are located on or near joints.
Irregularity
Irregularities of the scar surface that can be seen and felt (surface roughness or relief) include humps, bumps, ridges, folds or crisscross patterns.
Overall opinion
The overall opinion of the patient on the overall severity of their scar. This item should not be included in the sum score. This item is also not the mean score of all included items, and should be completed independently from the other 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.
Vascularity
The increased vascularization of the scar causes color changes (pink, red, blue or purple), which can be eliminated by pressing on the skin tissue with your finger or Plexiglas.. This is a good indicator of scar activity in the early maturation phase. Over time, scar activity will diminish and the redness will (partly) disappear.
Categories: pale | pink | red | purple | mixPigmentation
The light (hypopigmentation) or dark (hyperpigmentation) color of the scar, which remains after eliminating the influence of the vascularization on skin color by pressing on the scar with your finger or Plexiglas. Pigmentation disorders are caused by variation in the concentration of melanocytes in the epidermal layer and their melanin production. Significant pigmentation disorders will most likely remain in the long term.
Categories: hypo | hyper | mixRelief/texture
Irregularities of the scar surface (surface roughness or relief) are particularly seen after split skin autografting by using a meshed split skin graft. The irregularities result from secondary healing of the interstices of the meshed skin graft.
Categories: more | less | mixThickness
Scar tissue normally becomes thicker than the surrounding skin during the first months. After this period of time, scar thickness usually reduces. Some scars may remain hypertrophic (red, thick and often itchy) to some extent, while others may come atrophic (thin, pale and vulnerable).
Categories: thicker | thinnerPliability
Pliability is evaluated by picking up a scar, pinch it between thumb and index finger, and rolling it between the fingers like normal skin. Scar tissue is normally less supple than normal skin, because of thickness, stiffness, contraction and adhesions. This may cause functional impairment, especially when scars are located on or around joints.
Categories: supple | stiff | mixSurface area
The surface area of scars can either reduce or enlarge as a result of scar contraction or expansion, respectively. Scar contraction is mostly considered as a problem in burn scars where it may cause functional problems, whereas scar expansion or widening is often observed in linear scarring.
Categories: expansion | contraction | mixOverall opinion
The overall severity of the visual and tactile characteristics of the scar. This item should not be included in the sum score. This item is also not the mean score of all included items, and should be completed independently from the other items.