Defining a core outcome set for hypermobility spectrum disorders and hypermobile Ehlers-Danlos syndrome: A Delphi consensus study

The reported prevalence of hypermobility spectrum disorders (HSD) and hypermobile Ehlers-Danlos Syndrome (hEDS) is unclear due to complex presentations and lack of awareness amongst professionals, contributing to diagnostic and management uncertainties. Standardising an outcome measure to assess symptoms most important to patients should help determine the impact of interventions. This Delphi study aims to reach a consensus with stakeholders on the core outcome set for children and adults with HSD/hEDS. A three-round modified Delphi consensus study with a follow-up consensus meeting was used. Stakeholder groups consisted of (1) individuals with HSD/hEDS; (2) family/friends/carers and (3) healthcare professionals. Participants could belong to more than one stakeholder group. They rated 74 symptoms using a 9-point Likert scale: 1 "not important to 9 "critically important". Symptoms achieving a consensus rating of ≥ 70.0% critical importance across all groups were included. In Round 1, 766 responses were received from 600 participants, reducing to 566 responses from 438 participants by Round 3, with 53 participating in the consensus meeting. Overall, 30 symptoms met the ≥ 70.0% critically important threshold to be included in the final core outcome set. These were categorised under the specialties of musculoskeletal and orthopaedics, social, pain, gynaecology and urology, negative affect, neurological, gastrointestinal and "other". This study is the first to identify by consensus the core outcome set to be measured for patients with HSD/hEDS. The importance of these outcomes was confirmed by individuals living with the condition, their family, friends, carers and relevant healthcare professionals. Trial registration: IRAS ID: 326,855; East Midlands - Leicester South REC (reference: 23/EM/0143); Protocol registered with the COMET Initiative. Key Points • There is a lack of standardised outcome measure for HSD/hEDS research studies due to the heterogeneity of symptom presentations. • Symptoms across musculoskeletal and orthopaedics, social, pain, gynaecology and urology, negative affect, neurological, gastrointestinal and "other" specialties were identified as the core outcome set defined as ≥ 70.0% critically important to measure for individuals with HSD/hEDS. • There were a significant number of symptoms, widely recognised in the literature to be comorbid to HSD/hEDS, that reached a critical importance threshold of 50.0-69.9%, restricting the core outcome set to only those that met 70% or above may be limiting.