A Smartphone App-based Approach to Objectively Monitor Performance Outcomes in Degenerative Cervical Myelopathy: Benefits for Clinical Trial Efficiency

Introduction: Degenerative cervical myelopathy (DCM) is the leading cause of adult spine dysfunction worldwide, highlighting the urgent need for new treatments. Clinical trials in DCM are challenging due to high costs, as detection requires specialist knowledge, and the progressive nature of the disease demands elevated recruitment targets to mitigate dropout rates. We developed a smartphone app called ‘MoveMed’, which combines background monitoring with interactive on-screen assessments to objectively measure finger dexterity, balance and walking in people living with DCM. This study assessed whether these assessments could reduce clinical trial sample size and duration, without compromising power, as compared to the mJOA score.

Methods: Monte Carlo Simulation was used to evaluate critical sample size, study duration and power in a two-arm continuous outcome superiority trial. Performance outcomes at 3, 6, and 12 months were set as co-primary endpoints. These were measured using the mJOA score and the four MoveMed tests (‘Fast Tap,’ ‘Type,’ ‘Hold,’ and ‘Stand and Walk’ tests). Repeated measures of the outcomes were modelled for 362 patients over 10,000 iterations using parameters, input data and assumptions from the CSM-Protect, RECEDE-DCM and EMPOWER trials. Statistical significance was set at 5% whilst the minimally acceptable level of power was set at 80%. Critical sample size, study duration and statistical power were computed for three different scenarios: assuming weak (0.2), moderate (0.5) and strong (0.8) correlations across repeated measures of the outcomes.

Results: Critical sample sizes and study duration with MoveMed were comparable to those using the mJOA score across all correlation scenarios. The use of MoveMed in detecting treatment superiority attained similar rates of statistical significance as the use of the mJOA score without compromising power.

Conclusion : Objective performance measures are crucial for clinical trials in DCM. Our findings suggest that MoveMed outcomes could be used in DCM to detect changes in performance without compromising power, sample size or study duration. Remotely administered, on-screen assessments could help improve measurement in DCM: an AO Spine research priority.