Background: Rare diseases are associated with unique challenges encountered in diagnosis, treatment and conduct of clinical research. Desmoid tumour (DT) is one such ultra-rare malignancy about which awareness among medical professionals remains limited. We developed a questionnaire to assess knowledge, attitude and practice (KAP) among medical professionals on DT.

Methods: E-Delphi method was used for the assessment of KAP for DT amongst clinical experts (experience of >/= 3 years in DT). 22 open-ended statements were developed by the core research group using current consensus guidelines. In round 1, experts provided subjective feedback which was incorporated into a 35-item questionnaire. Round 2 entailed experts giving feedback as a 5-point Likert scale classified into agreement (median score >/=4), neutral (median score 3) and disagreement (median score <3). Feedback from Round 2 was incorporated and questions with neutral consensus were modified. Questions in Round 3 achieved consensus if >/= 75% participants agreed.

Results: 11 (64.7%) of 17 contacted experts responded in Round 1 including 6 (54.4%) who gave additional inputs and 5 (45.6%) who agreed to all statements. In round 2, 8 out of 11 experts responded to the 35-item questionnaire on knowledge (n = 16), attitude (n = 8) and practice (n = 11). 32 questions obtained agreement and 3 (8.5%) had neutral consensus. These were modified for round 3, in which consensus on 2 (66.6%) was attained. The final questionnaire comprises 34 items with 15, 8 and 11 questions on in the sections of knowledge, attitude and practice (KAP), respectively.