COMPARISON OF TWO DIFFERENT APPROACHES TO INVOLVE PARTICIPANTS IN CONSECUTIVE ROUNDS OF A DELPHI CONSENSUS TECHNIQUE.

Background: There is no guidance on which participants to invite to consecutive rounds of a Delphi exercise. There are two options: 1) Invite only participants that have completed the previous round for the consecutive round; 2) Invite every participant for all consecutive rounds irrespective of whether they have responded. It is unknown whether different invitation-procedures provide similar results. Objectives: To investigate the effect of two different approaches to involve participants in consecutive rounds of a Delphi exercise on response rate and final outcome. Methods: Patients with and experts in spondyloarthritis were invited to partake in a 3-round Delphi exercise to update a core outcome set. A randomised controlled study with 1:1 allocation to two experimental groups was built in, to compare two approaches of invitation. The ‘all-rounds group’ includes patients invited for each round independent of response to the previous round; the ‘respondents group’ includes patients invited for the next round only if they responded to the previous round. A 9-point Likert scale (1=not important; 9=critical) was used to score the importance of domains. Additionally, participants provided their six most important domains. Results: The overall response rate after 3 rounds was lower in the ‘respondents’ compared to the ‘all-rounds group’ (46% vs. 61%) (table 1). After the final round, the 4 outcomes with the highest percentage of votes were identical between experimental groups, with only small differences in percentages between groups (table 2). The only difference in the 6 most important domains was selection of disease activity by the ‘respondents group’, whereas the ‘all-rounds group’ selected overall functioning & health, while these domains were ranked as the 7th domain in the other group. Conclusion: Inviting persons for all rounds irrespective of a response to the previous round increases the generalisability, while the content of the outcome of a Delphi procedure is similar to using data of those persons who participate in all rounds only. Disclosure of Interests: Anne Boel: None declared, Victoria Navarro-Compan Consultant of: Abbvie, Lilly, Novartis, Pfizer, UCB, Speakers bureau: AbbVie, MSD, Lilly, Novartis, Pfizer, UCB, Robert B.M. Landewe Consultant of: AbbVie; AstraZeneca; Bristol-Myers Squibb; Eli Lilly & Co.; Galapagos NV; Novartis; Pfizer; UCB Pharma, Desiree van der Heijde Consultant of: AbbVie, Amgen, Astellas, AstraZeneca, BMS, Boehringer Ingelheim, Celgene, Cyxone, Daiichi, Eisai, Eli-Lilly, Galapagos, Gilead Sciences, Inc., Glaxo-Smith-Kline, Janssen, Merck, Novartis, Pfizer, Regeneron, Roche, Sanofi, Takeda, UCB Pharma; Director of Imaging Rheumatology BV