From qualitative data to a measurement instrument: A clarification and elaboration of choices made in the development of the Patient Scale of the Patient and Observer Scar Assessment Scale (POSAS) 3.0

To clarify and elaborate on the choices that were made in the development of the Patient Scale of the Patient and Observer Scar Assessment Scale 3.0 (POSAS 3.0), based upon the rich information obtained from patients during focus groups and pilot tests. The discussions described in this paper are a reflection of the focus group study and pilot tests that were conducted in order to develop the Patient Scale of the POSAS3.0. The focus groups took place in the Netherlands and Australia and included 45 participants. Pilot tests were performed with 15 participants in Australia, the Netherlands, and the United Kingdom. We discussed the selection, wording and merging of 17 included items. Additionally, the reason for exclusion of 23 characteristics are given. Based upon the unique and rich material of patient input obtained, two versions of the Patient Scale of the POSAS3.0 were developed: the Generic version, and the Linear scar version. The discussions and decisions taken during the development are informative for a good understanding of the POSAS 3.0 and are indispensable as a background for future translations and cross-cultural adaptations. •The Patient Scale was meant to be concise, readily assessable, quick, and user-friendly instrument assessing the key attributes of scar quality.•Two versions have been developed, the Generic version (total of 16 items), and the Linear scar version (total of 17 items).•Eight of the identified characteristics were merged into three included items.•Twenty-three characteristics were excluded during different phases of the development process for multiple reasons.