To establish clinical trial readiness for dystonia, a crucial step is to develop a Patient-Centered Outcome (PCO) measure to capture therapeutic response in focal dystonia such as in cervical dystonia (CD). Botulinum neurotoxin (BoNT) is the gold standard treatment for focal dystonia and yields improvement; yet the therapy may not meet all patient expectations as there is a high rate of discontinuation. A PCO that can measure therapeutic response, including the waxing and waning benefit of BoNT, across multiple domains and is easy to use on a frequent basis in the home environment is critical.
A modified iterative Delphi process based on FDA (Food and Drug Administration) guidelines was used to develop and select items to document patient symptoms and response to treatment. Potential items then were improved using patient focus groups, validated for content with specialist panels, and confirmed items based on a patient survey. Using data from 200 CD patients in the Dystonia Coalition Natural History Database, initial PCO items were identified. Utilizing Random Forests, prospective items were analyzed for their contribution to the overall severity scores on the clinical and patient-centered outcome scales. Items that were repetitive were merged. Iterative meetings with a specialist panel consisting of neurologists, physical therapists, and Patient Advocacy Group (PAG) representatives as well as virtual focus groups of CD patients were held. An online survey was conducted with over 600 CD patients participating. Finally, specialist panel members provided input for a content validity ratio (CVR) with iterations until there was good agreement as to the relevance and clarity of the items.
PCO measures tailored for CD were successfully developed. The PCO consists of 16 items covering three domains (motor, disability, and psychosocial) and reflects the input of international specialist panels, more than 800 CD patients, and PAGs (patient advocacy groups) following FDA guidance. The PCO is simple enough to be used in an app-based format compatible with smartphones and tablets.
This comprehensive CD PCO measure was developed through the combination of using robust existing patient centered data (from previous Dystonia Coalition Projects); active engagement with PAGs to provide the patient voice; and use of virtual focus groups and online surveys. This PCO will be used in a prospective study to characterize the therapeutic response to BoNT over time. This will provide peak effect size as well as capturing the “yo-yo” effect during BoNT treatment; and will prepare for a future trials.