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The Evidence Basis for Scar Severity Assessment and Scar Treatments – Do we actually know what we would like to think we know?

Special Reports

by Mr Ciaran O’Boyle


Scars and healed wounds

Wounding is not a natural process and the biological processes that deal with wounds are not regarded as normal either. Therefore, it is not valid to describe any scar as “normal”. This would seem to be readily understandable, even axiomatic. However the lack of firm concepts about what scars should look like or behave
like (what should be regarded as a “normal scar”), underpins both doctors’ difficulty in assessing scars and variability in those assessments. In addition, the visible appearance of a scar is only one component of what may be a highly-complex set of symptoms and physical problems including: pain; tenderness; itch; altered sensation; reduced ability to move; psychological or psychiatric issues.

Rating scars

When is a scar a bad scar? This question is one that is pondered frequently by specialists taking instruction in medicolegal cases which, on the face of it, may seem to be easily answered in an understandable way. However attempts to evaluate scars for diagnosis and severity are fraught and highly-susceptible to subjective influences. Efforts to achieve objectivity in scar assessments have led to the development of many types of devices to measure certain physical attributes of skin [1]. Whilst these devices provide numeric data which can be used for comparison of outcomes, the techniques require training; they are highly userdependent and liable to considerable variation in results when used by individuals of different experience. As a result, devices have not been adopted generally and largely remain research tools.

In the absence of an ideal scarometer, various clinical methods to rate scars have been developed. The number of different scar scoring systems available should serve as a cautionary guide to their fallibility. The most widely-recognised and extensively-published scar scores are described below. It should be remembered that although these scores may prove useful in assessing and comparing outcomes, they are highly-flawed as diagnostic tools and should not be
considered as a means of diagnosis of hypertrophic or keloid scarring.

Vancouver Scar Scale (VSS)

This is a long-established means of scar evaluation [2,3], which uses an assessment of four features of scars: Vascularity; height & thickness; pliability; and colour. Patient perceptions are not assessed in this scoring system. Some evidence is available showingmoderate or good correlation between the VSS score and objective techniques to assess cutaneous physical characteristics. The VSS remains applicable for evaluation of therapy and surgical outcomes in burns, but is yet to be adopted in general clinical use.

Patient and Observer Scar Assessment Scale (POSAS) This scale overcomes some criticisms of the VSS, in that it combines assessments of several physical features by both doctor (the observer) and patient, together with subjective, patient assessments [4]. The POSAS is still the only widely-recognised scale that
considers subjective symptoms, but lacks information on function and quality of life [5]. The POSAS scale is subject to some criticism. Analysis has shown that the observer's opinion and patient's opinion may be primarily influenced by different components of the assessment scheme [6]. Anecdotally, researchers report suspicion that many patients will tend to underestimate the severity of their scars, when presented with the POSAS scale. Furthermore, the scale is relatively cumbersome, requiring about 10 minutes to complete and patients with multiple scars, or scarring over a large area, may require multiple POSAS scales to be completed at each assessment.

Manchester Scar Scale

Proposed in 1998, this scale was an attempt to introduce a more quantitative element into scar assessment [7]. It differs from the POSAS and VSS in that it includes an additional 1-10 overall score and details on race, ethnic background, history, cause, symptoms, treatments, and responses. These additional data have been shown to improve the degree of agreement in scores between different clinical observers [8]. However, likely due to the time involved in filling this more cumbersome questionnaire, it has not been adopted in clinical practice. A further important caveat should be highlighted, in that this score was intended to be a means of comparing scars and measuring improvements or deterioration over time. It is not and could not be a means of diagnosis of hypertrophic or keloid scars.

Treating scars

What treatment or treatments are necessary to improve this person's scars?

The answer to this question will vary tremendously, depending upon the specialist of whom it is asked. Treatment options for scars were discussed recently in this journal, by Shokrollahi [9], who described 15 different treatment types. This list itself was not exhaustive. Additional scar treatments include intralesional cryotherapy and electrochemotherapy as well as other mainly research-based treatments still under evaluation. However, as is the case with scar scoring systems, the fact that so many different types of treatment available should be a reasonably good indication that no treatment is fully effective in all patients.

In determining which treatment to use for any particular condition, doctors often rely upon national or international guidelines, which in turn tend to be based upon systematic reviews of numbers of randomised controlled studies, involving large numbers of patients, often tens of thousands. The quality of evidence on which treatment decisions are made is often quoted as a Level of Evidence. The Oxford (UK) Centre for Evidence-Based Medicine (CEBM) [10] developed this scheme for ranking the available evidence for treatments, giving levels of evidence for statements regarding treatment effects and outcomes. CEBM levels of evidence

1a: Systematic reviews of randomized controlled trials

1b: Individual high quality randomized controlled trials

1c: All-or-none randomized controlled trials

2a: Systematic reviews of cohort studies

2b: Individual cohort study or low quality randomized controlled trials

2c: Outcomes Studies

3a: Systematic review of case-control studies

3b: Individual case-control study

4: Case series (and poor quality cohort and case-control studies)

5: Expert opinion without critical appraisal, or based on physiology or first principles

While occasional published evidence on scar treatments may approach Level 2b, the vast majority of published evidence sits in and around Level 4. This
compares very unfavourably when compared to treatments of medical conditions like hypertension or heart disease, which will rely heavily upon evidence of levels 1 and 2.

Who do we believe?

Expert witness testimony is a mixture of statements of evidence-based fact and statements based upon the individual expert’s personal experience. With respect
to scarring, both foundations are valid. In some respects they have to be as the bulk of clinical consensus in scar assessments and treatments relies upon experience; whenever an objective evidence base is present, this is mostly of a fairly low level.

Methods of scar evaluation and diagnosis are notoriously subjective and susceptible to errors, both by patients and the clinicians evaluating them. Even scar assessment scores that purport to be “objective” contain overt subjective terms in their evaluation criteria and researchers reporting outcomes of scar treatments often conclude that further more technical, non-standard methods of scar evaluation (for example, by recording images or 3-dimensional

impressions and casts) may be required, in addition to scar outcome scores, in order to truly provide “objective” data. The result of this is that, to some extent,
statements about scar severity and outcomes will necessarily involve subjectivity on the part of medical expert witnesses.

Good quality, prospectively-recruited, adequatelyblinded, randomised controlled clinical trials are sparse in scar and wound management, as are systematic reviews. As a result, the leading international guidelines on scar management were derived from consensus groups, rather than “pure” scientific evaluation [11,12]. The fact that these guidelines, published in 2002, have never satisfactorily been superseded is strong evidence of lack of: agreement; understanding and even motivation among doctors who assess and treat scars across the world.

Medical experts try to assist courts by providing impartial assessment of scars and applying their knowledge and experience to provide opinion on the best way to treat scars that are problematic. That knowledge and experience is the foundation of a doctor's entitlement to be called an "expert"[13]. However, given current knowledge and evidence, medical experts may be unable to provide advice regarding prognosis, severity and treatment, with satisfactory degrees of certainty. This renders more significant, a specialist's personal clinical experience. Although it may seem unsatisfactory to base conclusions about prognosis or best treatments upon personal experience rather than systematic reviews and randomised controlled trials, the unpalatable truth is that, with respect to scars, the evidence base does not support provision of opinion based solely upon published data.

Mr Ciaran O'Boyle Consultant Plastic Surgeon MD, FRCS (Plast), BSc
Mr Ciaran O’Boyle is a Consultant Plastic Surgeon and Honorary Assistant Professor at the University of Nottingham. He has a wide range of expertise in reconstructive and aesthetic surgery, burn care, trauma, scarring, skin cancer and surgery for facial paralysis. Mr O'Boyle regularly receives instructions for medical assessments and expert opinion in cases of personal injury, scarring and disfigurement. BMI The Park Hospital Sherwood Lodge Drive, Nottingham, NG5 8RX Tel: 0115 966 2119 Email: This email address is being protected from spambots. You need JavaScript enabled to view it. Web: www.ciaranoboyle.co.uk


1. Fearmonti R, Bond J, Erdmann D, Levinson H. A Review of Scar Scales and Scar Measuring Devices. Eplasty. 2010 (June); 10: e43.

2. Nedelec B, Shankowsky A, Tredgett EE. Rating the resolving hypertrophic scar: comparison of the Vancouver Scar Scale and scar volume. J Burn Care Rehabil. 2000; 21: 205–212.

3. Sullivan T, Smith J, Kermode J, et al. Rating the burn scar. J Burn Care Rehabil. 1990; 11: 256–260.

4. Draaijers LJ, Tempelman FR, Botman YA, et al. The Patient and Observer Scar Assessment Scale: a reliable and feasible tool for scar evaluation. Plast Reconstr Surg. 2004; 113: 1960–1965.

5. Truong PT, Lee JC, Soer B, et al. Reliability and validity testing of the Patient and Observer Scar Assessment Scale in evaluating linear scars after breast cancer surgery. Plast Reconstr Surg. 2007; 119(2): 487–94.

6. Roques C, Teot L. A critical analysis of measurements used to assess and manage scars. Int J Lower Extr Wounds. 2007; 6(4): 249–253.

7. Beausang E, Floyd H, Dunn KW. A new quantitative scale for clinical scar assessment. Plast Reconstr Surg. 1998; 102: 1954– 61.

8. Sullivan T, Smith J, Kermode J, et al. Rating the burn scar. J Burn Care Rehabil. 1990; 11: 256–60.

9. Shokrollahi K. Assessment and Treatment of Scars. The Expert Witness. 2015/16; 1(14): 65-67.

10. http://www.cebm.net/oxford-centre-evidence-based-medicinelevels- evidence-march-2009/

11. Mustoe TA, Cooter R, Gold M, Hobbs R, Ramelet AA, Shakespeare P, et al. International clinical guidelines for scar management. Plast Reconstr Surg 2002; 110: 560-72.

12. Mustoe TA. Scars and keloids - Several treatments are used, but the evidence base is lacking. BMJ. 2004; 328: 1329–1330.

13. S Al-Benna, C O’Boyle. Burn care experts and burn expertise. Burns 40(2): 200-203.

We would like to say  

Give precise, quantitative and reproducible scar assessments.

Provide evidence-based treatment plans, with nationally-agreed first-, second- and third-line treatment options, to allow for treatment failures.

Give evidence-based opinion on prognosis and final outcome.

Why we might not be able to

No single, common scar assessment scale.

International Guidelines are a consensus statement only.

Low levels of evidence for all treatments.

Variable nature of wound healing. No definitive scar outcomes analysis

Valid criticisms of statements

What is meant by "a hypertrpohic scar"?

What is meant by "a bad scar"?

Why commit the patient to a series of expensive and probably ineffective steroid injections?

Why jump to recommend that expensive and unproven treatment?

Upon what evidence base do you give that prognosis?