Formative research in the codesign of a discrete choice experiment with patients with myasthenia gravis: selecting and refining attributes, levels and scenarios

Introduction: Given the substantial burden faced by patients with myasthenia gravis (MG), including the disease itself, treatment-related side effects, the invasiveness of certain interventions and the time spent in seeking and receiving care, it is essential to understand patient preferences to inform resource allocation and enhance patients’ quality of life. Objective: The aim of this study was to co-design the MG treatment choice tasks with patients for a discrete choice experiment (DCE) using a multi-stage, mixed-methods approach involving the nominal group technique (NGT) and focus groups. Methods: MG patients in Australia were invited to participate in two of eight 1-hour online sessions in July and August 2024. Each session included four to six patients and was facilitated by three researchers. Participants were presented with three MG scenarios: ‘mild exacerbation’, ‘severe exacerbation’ and ‘maintenance phase’. During NGT sessions, patients shared their experiences with MG treatments, proposed DCE attributes and ranked their importance for each scenario. Attribute rankings were normalised to a 0–1 scale, averaged within each session and combined using a weighted mean adjusted for group size. The rankings were used to prioritise attributes for inclusion in DCEs. In subsequent focus groups, patients reviewed draft DCE scenario descriptions and provided feedback on the clarity and relevance of attribute descriptions and levels. Throughout the process, research team discussions were held to discuss clinical and methodological relevance of the emerging results. Results: Nineteen patients with MG aged 35–82 years (12 females, 7 males) participated in four online NGT and four focus group sessions, identifying 31 attributes across treatment administration (n = 10), side effects (n = 16) and treatment outcomes (n = 5). Attribute rankings varied by scenario, with ‘recommended by neurologist’, health care workers’ knowledge of the treatment’ and ‘easy access to treatment’ being consistently top-ranked among treatment administration attributes. Side effects ranged broadly, from gastrointestinal issues to skin cancer. For treatment outcome attributes, ‘chance to improve’ was most highly ranked for mild and severe exacerbation scenarios, whereas ‘risk of getting severely worse’ and ‘duration of effectiveness’ were equally top-ranked for the maintenance scenario. Attribute rankings and patient perspectives were balanced with DCE methodological considerations and clinician input to finalise attributes for each scenario, including grouping similar side effects to describe a few attributes and retaining the ‘cost to patient’ attribute despite it being a low patient priority to allow trade-off analysis in the resulting choice data. A final list of seven attributes was selected for both the mild exacerbation and maintenance scenarios. Discussions from focus groups and research team deliberation further refined scenario descriptions and attribute levels to enhance relevance and clarity. Conclusion: This study reinforces the value of a blended and staged approach of combining NGT and focus group sessions with multidisciplinary research team discussions to shape the development of patient-centred research in DCE design.