Plain English summary
The Patient and Observer Scar Assessment Scale (POSAS) consists of two separate scales: the Patient Scale and the Observer Scale and measures scar quality (i.e. how the scar looks and feels) from both perspectives. Over the years, the POSAS has become a well-known and widely used outcome measurement instrument for measurements of scar quality. However, the Patient Scale of the POSAS was developed by professionals without input from patients. Therefore, we felt a need to improve the Patient Scale by involving a large number of international patients in the development of a new version (i.e. the POSAS3.0). In six consecutive focus groups that took place in the Netherlands and Australia, scar patients discussed what they considered to be the most important characteristics of their scar. Based on these qualitative data, two final versions of the POSAS3.0, Patient Scale were developed and pilot tested.
The Linear Scar version is used specifically for linear scars, which are scars caused by surgery or trauma, which have a narrow and straight appearance.
The Generic version can be used for the assessment of all other scar types (except linear scars). Currently, the Patient Scale of the POSAS3.0 is being tested in patients with different types of scars to establish how valid and reliable the scale is able to measure scar quality. More information on the POSAS3.0 scales, and how to obtain and use them can be found on our website (
www.posas.org).
Introduction
Scar quality is a construct referring to the visual, tactile and sensory characteristics of the scar [
1,
2]. Standardized
scar quality assessments are necessary to measure the effectiveness of scar treatments, monitor scar maturation over time and identify the need for future treatments in both clinical research and individual patient care. Prior research has demonstrated that professionals and patients might have a different understanding, and therefore operationalization, of the construct
scar quality [
3‐
6]. As a result, exploration of both perspectives is vital in order to achieve a complete and thorough scar evaluation. For this reason, the POSAS was the first to include both perspectives using two separate scales: the Patient Scale and the Observer Scale [
7,
8]. Several systematic reviews on
scar quality scales have rated the POSAS as the best available scale, because it has good measurement properties, and includes a separate assessment for observers (often professionals), as well as for patients [
9‐
12]. However, the POSAS2.0, which dates back to 2005, has several limitations. First and foremost, the Patient Scale was developed by professionals without input from patients living with scars. Second, the Observer Scale was developed in the Netherlands and could be criticised for not having a more global perspective. As a result, we determined a need to improve the content validity (i.e. comprehensiveness of content, as well as relevance and comprehensibility of items), and the generalizability of the POSAS2.0. This was done by including a large number of international experts: patients as well as professionals in the development of a new version, i.e. the POSAS3.0. The objective of the present study was to develop the Patient Scale of the POSAS3.0 for measurements of
scar quality in adults with all types of scars. The POSAS3.0, Observer Scale has been developed using an extensive international Delphi study, which will be published separately.
Discussion
This study described the process of development and refinement of the Patient Scale of the POSAS3.0, which is suitable for measurements of
scar quality in adults with all types of scars. In a second, complementary, article, we clarify and elaborate on the choices that were made during the development of the scale regarding the selection, formulation and merging of items, using an in-depth insight into our qualitative data [
19]. The construct
scar quality encompasses visual, tactile and sensory characteristics of the scar, and does not include
systemic symptoms or the impact that scars may have on the quality of life of individuals living with them [
19].
The main reason for initiating this study was the lack of patient input in the development of the previous POSAS versions. Using a qualitative approach, this study aimed to establish how individuals with scars value and define the characteristics of
scar quality. By including
scar quality characteristics that individuals with scars find most important, using the language that they used to describe them with, we aimed to improve the content validity of the POSAS. For this reason, it is our intention to have the old versions of the POSAS replaced with the POSAS3.0 by users. The rigorous methodological approach used in the development of POSAS3.0 led to considerable differences in scale content compared to earlier versions. First, the total number of items included in the POSAS3.0, Patient Scale is higher (16 or 17 items) than in previous versions (6 items). The greatest difference is attributed to an increase in the number of sensory items—components which only patients are able to perceive and rate. The POSAS3.0, Patient Scale includes 11 sensory items, whereas the previous version only includes two sensory items (i.e. pain and itch). This difference highlights the added value in asking the patients for input. Secondly, the 10-point rating scale has been changed to a verbal rating scale with 5 response options. This decision was made because patients often found it difficult to discriminate between 10 different response options. This was also supported by Rasch analyses on the POSAS2.0, Patient Scale, which demonstrated a malfunctioning of the 10-point scale and suggested a reduction of the number of answering options [
20,
21]. Third, the POSAS3.0 contains clear instructions and questions in lay language, facilitating independent scale completion, whereas in previous versions, health care professionals often needed to provide additional clarification of questions as the questionnaire was completed by the patient. Despite the marked differences between POSAS3.0 and earlier versions, there are also similarities in scale content. Four items included in the POSAS2.0 (i.e. pain, itch, colour and irregularity) are also integral to the new version. Two remaining items, stiffness and thickness, are presented slightly different in the new scale, because patients preferred the use of the terms ‘hardness’ and ‘height’, respectively.
This study is the first international qualitative investigation into the patient’s perspective on
scar quality. A fundamental strength of this study is its thorough and iterative methodological approach. The research team was composed of clinimetric experts, clinicians and qualitative researchers, but patients with scars had input in all phases of the development process. In this way, we incorporated the theoretical knowledge regarding
scar quality, scale development and qualitative research with the diverse patient experience. In preparation for this study, an extensive systematic review of the literature was conducted [
2], which provided a complete overview of all the characteristics of
scar quality that had ever been measured. All focus groups were guided by experienced and certified moderators and surgical patients were recruited from a range of different surgical specialties (i.e. gynaecology, trauma, plastic surgery), which contributed to the generalizability of our results.
A potential disadvantage of focus groups in comparison to individual interviews is that participants are more likely to adopt and affirm each other’s opinions. We cannot exclude that this occurred in our focus groups. However, advantages of the focus group process are the ability for participants to identify and clarify their opinion, as well as to compare and revise it based upon the opinions of others [
22]. This may have led to more ideas about—and deeper insight into—the construct
scar quality than would have been identified in one-on-one interviews [
23‐
25]. Two distinct versions of the POSAS3.0 Patient scale were developed for different scar types (i.e. the Generic version and the Linear Scar version) to avoid misinterpretation of the item
scar widening by patients with non-linear scars. A limitation of our study is that a third POSAS version was deemed necessary for keloid patients, but we did not include enough keloid participants in the first phase of our study (
n = 3) to adequately develop this version. Further research is necessary to address this. Another limitation related to our study population is that the majority had burn scars. However, as burn scars are considered as one of the most complex and burdensome scars, we believe that no relevant characteristics have been missed. Currently, we are conducting follow-up studies with the Patient Scale of the POSAS3.0. In order to facilitate the calculation of the total score for
scar quality (e.g. a weighted scoring algorithm), we aim to determine the importance of individual items for the construct
scar quality. In addition, another follow-up study is being performed to establish the measurement properties (i.e. reliability, measurement error, responsiveness [
26]) of the POSAS3.0 Patient Scale. These findings will indicate if the qualitative methodology used in this development study have indeed led to improved measurement properties of the POSAS3.0 in comparison to the previous POSAS version. Furthermore, an international Delphi study has been conducted to better understand and evaluate the professional perspective on
scar quality. This led to the development of the Observer Scale of the POSAS3.0. Together, both scales fo the POSAS3.0 will provide a comprehensive
scar quality assessment in adults with all scar types. More information on how to obtain and use the POSAS3.0 scales can be found on our website (
www.posas.org).
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