N-of-1 Trial Methodology

Simulation-based evaluation of N-of-1 versus parallel-group designs for biomarker-validated treatments

2026-06-07 18:16 PDT

Overview

N-of-1 trials – crossover designs in which a single subject serves as their own control across multiple treatment periods – offer substantial power advantages when treatment effects are heterogeneous across individuals. For chronic diseases such as Alzheimer’s and PTSD, where individual response patterns are highly variable and biomarker-validated patient stratification is increasingly feasible, N-of-1 designs deserve systematic methodological evaluation against conventional parallel-group randomized controlled trials.

This program develops a coordinated series of simulation studies comparing N-of-1 and parallel-group architectures across the design dimensions most consequential for Alzheimer’s disease and PTSD trials: carryover effects, serial correlation, dropout patterns, biomarker- treatment interaction, and the statistical procedures applied at the analysis stage.

Papers in development

  • Comparative statistical power of N-of-1 trials versus parallel-group RCTs: a simulation study of prazosin for PTSD nightmares.
  • Robustness of carryover-mitigation analysis strategies: a factorial simulation study.
  • Latent-class and mixture-model formulations for biomarker-treatment interaction in N-of-1 trials.
  • Three-component decomposition of treatment response in aggregated N-of-1 trials: pharmacological, expectation-driven, and natural-history components.
  • Informative dropout and trial-design choice in aggregated N-of-1 biomarker-validation trials.

Methods

Monte Carlo simulation under the ADEMP framework; linear mixed-effects models (MMRM and RM-ANOVA); latent-class and mixture models; Gompertz response functions; empirically derived variance-covariance matrices from ADCS trials; carryover-sensitivity factorial designs.

Software

  • nof1power – Power analysis and simulation for N-of-1 trials, implementing the core simulator described in the paper series.

Publications

Hendrickson RC, Thomas RG, Schork NJ, Raskind MA (2020). Optimizing aggregated n-of-1 trial designs for predictive biomarker validation: statistical methods and theoretical findings. Frontiers in Digital Health. https://doi.org/10.3389/fdgth.2020.00013

Earlier work on N-of-1 design and power is accessible through the full publications list by filtering on the keyword simulation.