Exploring synthetic controls in rare diseases with a proof of concept in spinal cord injury

Louis P Lukas1,2, Samuel Håkansson1,2, Miklovana Tuci1,2,3

  • 1Department of Health Sciences and Technology (D-HEST), ETH Zurich, Zurich, Switzerland.

BMC Medicine
|October 24, 2025
PubMed
Abstract

Insights

Synthetic controls, generated from patient recovery predictions, offer a solution for rare disease clinical trials. This approach reduces patient recruitment challenges and intercohort heterogeneity in spinal cord injury (SCI) studies.

Area of Science:

  • Neurology
  • Biostatistics
  • Clinical Trial Design

Background:

  • Clinical trials for rare and heterogeneous disorders like spinal cord injury (SCI) face significant challenges in patient recruitment and translating preclinical findings.
  • Synthetic controls, derived from data-driven recovery predictions, are proposed to mitigate these issues.

Purpose of the Study:

  • To benchmark data-driven prediction architectures for neurological recovery after SCI.
  • To develop and validate synthetic controls for use in clinical trials for rare diseases.

Main Methods:

  • Constructed synthetic controls using personalized predictions of neurological recovery (segmental motor scores) from European Multicenter Study about Spinal Cord Injury (EMSCI) and Sygen trial data.
  • Compared six architectures (linear, tree, deep learning) and identified the best-performing model.
  • Validated synthetic controls via simulation and a post hoc re-evaluation of the Nogo Inhibition in SCI (NISCI) trial.

Main Results:

  • A convolutional neural network achieved the best performance in predicting motor score recovery.
  • Trial simulations demonstrated that synthetic controls reduce intercohort heterogeneity compared to traditional randomization.
  • The case study showed no significant differences between synthetic and randomized controls.

Conclusions:

  • Data-driven prediction models provide individual recovery forecasts and form the basis for synthetic controls.
  • Synthetic controls can address challenges of small cohorts and recruitment in rare disease trials, potentially increasing patient access to investigational treatments.
  • A comprehensive benchmark of prediction architectures for SCI recovery is provided.