title: Bridging a translational gap: using machine learning to improve the prediction of PTSD.
abstract: BACKGROUND
  Predicting Posttraumatic Stress Disorder (PTSD) is a pre-requisite for targeted prevention. Current research has identified group-level risk-indicators, many of which (e.g., head trauma, receiving opiates) concern but a subset of survivors. Identifying interchangeable sets of risk indicators may increase the efficiency of early risk assessment. The study goal is to use supervised machine learning (ML) to uncover interchangeable, maximally predictive combinations of early risk indicators.
  
  
  METHODS
  Data variables (features) reflecting event characteristics, emergency department (ED) records and early symptoms were collected in 957 trauma survivors within ten days of ED admission, and used to predict PTSD symptom trajectories during the following fifteen months. A Target Information Equivalence Algorithm (TIE*) identified all minimal sets of features (Markov Boundaries; MBs) that maximized the prediction of a non-remitting PTSD symptom trajectory when integrated in a support vector machine (SVM). The predictive accuracy of each set of predictors was evaluated in a repeated 10-fold cross-validation and expressed as average area under the Receiver Operating Characteristics curve (AUC) for all validation trials.
  
  
  RESULTS
  The average number of MBs per cross validation was 800. MBs' mean AUC was 0.75 (95% range: 0.67-0.80). The average number of features per MB was 18 (range: 12-32) with 13 features present in over 75% of the sets.
  
  
  CONCLUSIONS
  Our findings support the hypothesized existence of multiple and interchangeable sets of risk indicators that equally and exhaustively predict non-remitting PTSD. ML's ability to increase prediction versatility is a promising step towards developing algorithmic, knowledge-based, personalized prediction of post-traumatic psychopathology.
authors.affiliation: Research and Knowledge Centre, Danish Veteran Centre, Garnisonen 1, 4100, Ringsted, Denmark. kikarstoft@health.sdu.dk.
authors.forename: Karen-Inge
authors.initials: KI
authors.lastname: Karstoft
authors.affiliation: Department of Psychiatry, NYU School of Medicine, New York, NY, USA. Isaac.Galatzer-Levy@nyumc.org.
authors.forename: Isaac R
authors.initials: IR
authors.lastname: Galatzer-Levy
authors.affiliation: Center for Health Informatics and Bioinformatics, NYU School of Medicine, New York, NY, USA. Alexander.Statnikov@nyumc.org.|Department of Medicine, NYU School of Medicine, New York, NY, USA. Alexander.Statnikov@nyumc.org.
authors.forename: Alexander
authors.initials: A
authors.lastname: Statnikov
authors.affiliation: Center for Health Informatics and Bioinformatics, NYU School of Medicine, New York, NY, USA. Zhiguo.Li@nyumc.org.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Psychiatry, NYU School of Medicine, New York, NY, USA. Arieh.shalev@nyumc.org.
authors.forename: Arieh Y
authors.initials: AY
authors.lastname: Shalev
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology*; D000328:Adult; D000465:Algorithms; D001185:Artificial Intelligence; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012372:ROC Curve; D018570:Risk Assessment; D012307:Risk Factors; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D057170:Translational Research, Biomedical; D014947:Wounds and Injuries / Q000150:complications / Q000523:psychology