Validation by expert group

Statements drafted by the research group will be sent to the expert group to obtain a level of consensus and feedback. The receival of feedback will take place through a web-based questionnaire. Level of consensus is assessed on a 0–10 scale for each statement, in which 0 means ‘disagree’, 5 means ‘neutral’ and 10 means ‘agree’. Experts may provide comments or feedback on statements if desired. Furthermore, all experts will be given the opportunity to suggest additional statements and will be invited to leave further comments or advice for the research group. No discussion is allowed between the experts at this point of time.

Subsequently, an expert meeting will be held to discuss statements and feedback provided by the expert group. The expert meeting will be led by a member of the research group. Statements will be accepted if the expert group reaches a consensus of more than 75% on the statement.^{21 24} If consensus cannot be reached on a proposed statement during the expert meeting, the statements can be discarded, adjusted or reformulated. Steps 2 a and 2b can be repeated up to three times.^{21 24}