Staging model of PTSD: a strategy for the implementation of precision medicine in military settings.

Biomarkers have been of considerable interest in military medicine as a strategy to identify objective measures of resilience in the context of the cumulative trauma exposure of combat as well defining the emerging neurobiological dysregulation associated with post-traumatic stress disorder (PTSD). This body of work has been driven by the imperative of developing strategies to optimally manage the long-term health outcomes of personnel and finding novel treatment approaches. However, the challenge of defining the relevant phenotypes of PTSD and in the context of the multiplicity of biological systems of interest has hampered the identification of biomarkers that have clinical utility. One key strategy to improve the utility of precision medicine in military settings is to use a staging approach to define the relevant phenotypes. A staging model of PTSD captures the progression of the disorder and the transitions from being at risk to subsyndromal disorder and the path to chronic disorder.A staging approach addresses the longitudinal course of PTSD and the fluidity of the disorder across time. Staging describes how symptoms evolve into more stable diagnostic syndromes and the stepwise changes in clinical status which is key to the identification of phenotypes that can be tied to relevant biomarkers. When a population is exposed to a trauma, the individuals will be at different stages in the emergence of risk and the development of PTSD. The staging approach provides a method of capturing the matrix of phenotypes that need to be demarcated to study the role of multiple biomarkers. This paper forms part of the Special issue of BMJ Military Health dedicated to personalised digital technology for mental health in the armed forces.