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Validated Predictive Algorithm of Posttraumatic Stress Course following Emergency Department Admission after a Traumatic Stressor

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Annually, approximately 30 million patients are discharged from the emergency department (ED) after a traumatic event1. These patients are at substantial psychiatric risk, with approximately 10–20% developing one or more disorders, including anxiety, depression or post-traumatic stress disorder (PTSD)2–4. At present, no accurate method exists to predict the development of PTSD symptoms upon ED admission after trauma5. Accurate risk identification at the point of treatment by ED services is necessary to inform the targeted deployment of existing treatment6–9 to mitigate subsequent psychopathology in high-risk populations10,11. This work reports the development and validation of an algorithm for prediction of post-traumatic stress course over 12 months using two independently collected prospective cohorts of trauma survivors from two level 1 emergency trauma centers, which uses routinely collectible data from electronic medical records, along with brief clinical assessments of the patient’s immediate stress reaction. Results demonstrate externally validated accuracy to discriminate PTSD risk with high precision. While the predictive algorithm yields useful reproducible results on two independent prospective cohorts of ED patients, future research should extend the generalizability to the broad, clinically heterogeneous ED population under conditions of routine medical care.
Variable importance for the training set a, Variable importance using SHAP for the training set based on EMR data plus ISRC and PDEQ. The SHAP value is calculated for each feature by comparing what the model’s prediction would be without the feature and with the feature in every possible order of adding the feature to the model. The bar plot shows the mean absolute SHAP value per feature. The larger the SHAP value, the more important the feature is to discriminate between the non-remitting and resilient trajectory. b, SHAP summary dot plot (for the same analysis as in a) displaying features that influence model predictions of positive outcome (non-remitting class) the most. The higher the SHAP value of a feature, the higher the log odds of a non-remitting PTSD trajectory. Features are first sorted by their global impact (y axis). For every individual in the sample, a dot represents the attribution value for each feature from low (blue) to high (red). The density of the plot shows that the ISRC is the most important predictor and that higher ISRC levels give rise to higher SHAP values (higher probability to be in the non-remitting class) displayed on the x axis. Chloride (which is the most important predictor in the external test set; Supplementary Fig. 7) shows that a higher score increases the likelihood (a log odds ratio) of being assigned to the non-remitting trajectory by the model (higher SHAP value). c, SHAP variable importance for the training set using EMR data plus the four most predictive ISRC items. d, SHAP summary dot plot for the respective analysis from c. Self-report measures are colored in dark blue in a–c.
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Letters
https://doi.org/10.1038/s41591-020-0951-z
1Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, USA. 2Vagelos School of Physicians and Surgeons,
Department of Emergency Medicine, Columbia University Irving Medical Center, New York, NY, USA. 3Data Science Institute, Columbia University, New
York, NY, USA. 4Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA. 5Yerkes National Primate
Research Center, Atlanta, GA, USA. 6Ronald O. Perelman Department of Emergency Medicine, New York University Grossman School of Medicine,
New York, NY, USA. 7Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, MI, USA. 8Department of Counseling
and Clinical Psychology, Teachers College, Columbia University, New York, NY, USA. 9Center for Alcohol Use Disorder and PTSD, New York University
Grossman School of Medicine, New York, NY, USA. 10Dell Medical School, Department of Psychiatry, University of Texas at Austin, Austin, TX, USA.
11Institute for Early Life Adversity Research, University of Texas at Austin, Austin, TX, USA. 12McLean Hospital, Harvard Medical School, Boston, MA, USA.
13AiCure LLC, New York, NY, USA. e-mail: ks3796@cumc.columbia.edu
Annually, approximately 30 million patients are discharged
from the emergency department (ED) after a traumatic
event1. These patients are at substantial psychiatric risk,
with approximately 10–20% developing one or more disor-
ders, including anxiety, depression or post-traumatic stress
disorder (PTSD)24. At present, no accurate method exists to
predict the development of PTSD symptoms upon ED admis-
sion after trauma5. Accurate risk identification at the point
of treatment by ED services is necessary to inform the tar-
geted deployment of existing treatment69 to mitigate sub-
sequent psychopathology in high-risk populations10,11. This
work reports the development and validation of an algorithm
for prediction of post-traumatic stress course over 12 months
using two independently collected prospective cohorts of
trauma survivors from two level 1 emergency trauma centers,
which uses routinely collectible data from electronic medical
records, along with brief clinical assessments of the patient’s
immediate stress reaction. Results demonstrate externally
validated accuracy to discriminate PTSD risk with high preci-
sion. While the predictive algorithm yields useful reproduc-
ible results on two independent prospective cohorts of ED
patients, future research should extend the generalizability to
the broad, clinically heterogeneous ED population under con-
ditions of routine medical care.
Previous studies identified multiple trauma-related predic-
tive signals of PTSD risk7,1217, including aspects of the biologi-
cal stress response1823, immune response2426, threat perception,
psychophysiological arousal15,19,27 and psychosocial determinants
of clinical risk28. Many indicators related to these biological sys-
tems and psychosocial indicators are routinely collected in the
ED and logged in the electronic medical records (EMRs), mak-
ing them viable as candidate predictors of risk. Some factors, such
as self-reported psychological stress, are not yet part of the medi-
cal routine and only about 7% of level 1 trauma centers routinely
screen for PTSD29.
Notably, PTSD comes with long-term clinical and pecuniary costs
to both the individual and the healthcare system. While empirically
validated treatments are effective in reducing the risk for PTSD6,8,9,
early prevention strategies are typically not implemented due to the
lack of established methods for timely and reliable risk identifica-
tion11. The ED visit is often the sole contact of trauma survivors
with the healthcare system and the time immediately after trauma
opens a critical window to prevent the development of PTSD11,30.
Accurate identification of risk for PTSD during ED evaluation using
algorithms running on accessible data sources would provide new
opportunities for cost-effective and scalable methods of risk assess-
ment and intervention to reduce the prevalence of PTSD without
posing high additional burden for ED personnel11.
The use of predictive models to integrate multiple post-traumatic
stress (PTS) risk indicators has demonstrated moderate to strong
predictive accuracy on a proof-of-concept level1214. However, the
frequent lack of external validation in the literature obscures the
generalizability of model performance31,32, ultimately hampering the
implementation of such algorithms in clinical practice. Recognizing
the high clinical need, the US National Institute of Mental Health
has funded a large multi-site consortium that will start to collect
data from independent sites33 suitable to evaluate the reliability
of emerging predictive models of PTS course. Independently of
this effort, large hospital systems are actively working to identify
novel methods that can be integrated into the standard of care to
improve patient outcomes and decrease long-term costs to the hos-
pital system34. Together, there is an indication of both the necessary
research and clinical interest in the development and deployment of
data-driven approaches to predict the clinical risk of psychopathol-
ogy in the context of ED healthcare.
We set out to develop and test the prediction of PTSD symptom
development in a reproducible way across independent samples. At
two independent sites (Supplementary Figs. 1 and 2), ED patients
who reported experience of a traumatic event according to trauma
criterion A35 were enrolled in a prospective longitudinal cohort.
A validated predictive algorithm of post-traumatic
stress course following emergency department
admission after a traumatic stressor
KatharinaSchultebraucks 1,2,3 ✉ , AriehY.Shalev1, VasilikiMichopoulos4,5, CoritaR.Grudzen6,
Soo-MinShin6, JenniferS.Stevens 4, JessicaL.Maples-Keller4, TanjaJovanovic7, GeorgeA.Bonanno8,
BarbaraO.Rothbaum4, CharlesR.Marmar1,9, CharlesB.Nemeroff10,11, KerryJ.Ressler4,12 and
IsaacR.Galatzer-Levy1,13
NATURE MEDICINE | VOL 26 | JULY 2020 | 1084–1088 | www.nature.com/naturemedicine
1084
Content courtesy of Springer Nature, terms of use apply. Rights reserved
... A total of 30 studies were included in this Analysis (Table 1): 12 crosssectional studies 26-37 and 18 longitudinal studies [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] . Most of the studies focused on post-trauma variables only (n = 26) [26][27][28][29][30][31][32][33][34][35][36][38][39][40][41][42][43][44][45][46][47][48][49][50][51] , whereas one study assessed both pre-trauma and post-trauma variables 53 and three studies focused on pre-trauma variables 52,54,55 . ...
... A total of 30 studies were included in this Analysis (Table 1): 12 crosssectional studies 26-37 and 18 longitudinal studies [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] . Most of the studies focused on post-trauma variables only (n = 26) [26][27][28][29][30][31][32][33][34][35][36][38][39][40][41][42][43][44][45][46][47][48][49][50][51] , whereas one study assessed both pre-trauma and post-trauma variables 53 and three studies focused on pre-trauma variables 52,54,55 . Twenty-one studies used a classification approach to predict probable PTSD diagnosis (n = 12) 27,28,30,31,34,36,37,44,47,50,51,55 , PTSD trajectory membership from latent growth mixture models (n = 6) 39-42,46,53 , both (n = 2) 45,52 or symptom profile from latent profile analysis (n = 1) 54 . ...
... Only four studies used the gold standard and validated the generalizability of the results using an external sample 43,46,51,55 , and eight studies validated their model in a holdout set 26,30,38,45,47,[50][51][52] . In addition, 13 studies used resampling techniques 26,30,[38][39][40]43,[45][46][47][50][51][52]55 such as crossvalidation (k-folds 30,43,46,51,55 and leave-one-out 26,38,45,50,52 ) and bootstrapping 39,40,47 techniques, 3 used nested cross-validation 28,35,42 and 4 studies did not specify their validation method 29,33,34,53 . ...
... Previous research reported a broad range of risk and protective factors for PTSD, including demographic; socio-economic; psychiatric; psychosocial; biological; trauma history; and environmental domains [19][20][21][22]. Recent studies with a computational approach strongly indicate that these risk and protective factors for PTSD interact in dynamic non-linear ways and seem to differ between PTSD symptom trajectories (e.g., [23,24]). Increasing empirical evidence supports the existence four common distinct courses or trajectories of PTSD symptoms following trauma exposure [25]. ...
... A growing number of studies support the potential of machine learning in prognostic risk classification. These studies achieved good accuracy in classifying recently traumatized individuals into their subsequent PTSD diagnostic status and/or symptom trajectory (e.g., [23,24,[26][27][28][29][30]). However, most of these existing prognostic risk classification models cannot be applied beyond acute medical care settings, as they mainly include acute biomedical and hospital patient record information. ...
... The test sets require a sample size of n = 75 (n = 6 cases; n = 69 non-cases) for men, and n = 82 (n = 6 cases; n = 74 non-cases) for women. In order to meet the proposed rule of thumb of at least 25 cases available in the training set, this requires to include a minimum of 31 cases in both samples [24]. Expecting minimally the same allocation ratio of the chronic trajectory relative to the resilient and recovery trajectory as in the TraumaTIPS cohort, this translates into a total sample size of n = (74.964*5) ...
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Background Effective preventive interventions for PTSD rely on early identification of individuals at risk for developing PTSD. To establish early post-trauma who are at risk, there is a need for accurate prognostic risk screening instruments for PTSD that can be widely implemented in recently trauma-exposed adults. Achieving such accuracy and generalizability requires external validation of machine learning classification models. The current 2-ASAP cohort study will perform external validation on both full and minimal feature sets of supervised machine learning classification models assessing individual risk to follow an adverse PTSD symptom trajectory over the course of 1 year. We will derive these models from the TraumaTIPS cohort, separately for men and women. Method The 2-ASAP longitudinal cohort will include N = 863 adults (N = 436 females, N = 427 males) who were recently exposed to acute civilian trauma. We will include civilian victims of accidents, crime and calamities at Victim Support Netherlands; and who were presented for medical evaluation of (suspected) traumatic injuries by emergency transportation to the emergency department. The baseline assessment within 2 months post-trauma will include self-report questionnaires on demographic, medical and traumatic event characteristics; potential risk and protective factors for PTSD; PTSD symptom severity and other adverse outcomes; and current best-practice PTSD screening instruments. Participants will be followed at 3, 6, 9, and 12 months post-trauma, assessing PTSD symptom severity and other adverse outcomes via self-report questionnaires. Discussion The ultimate goal of our study is to improve accurate screening and prevention for PTSD in recently trauma-exposed civilians. To enable future large-scale implementation, we will use self-report data to inform the prognostic models; and we will derive a minimal feature set of the classification models. This can be transformed into a short online screening instrument that is user-friendly for recently trauma-exposed adults to fill in. The eventual short online screening instrument will classify early post-trauma which adults are at risk for developing PTSD. Those at risk can be targeted and may subsequently benefit from preventive interventions, aiming to reduce PTSD and relatedly improve psychological, functional and economic outcomes.
... This should be considered when interpreting our findings and represents a limitation of our study where future research would benefit from including questions about treatment history to enhance the understanding of its potential impact on PTSD outcomes. Gains have been made in recent years in integrating various acute variables into predictive models, which can potentially improve early identification of people who will develop PTSD [30,31]. Fifth, we did not use a clinical face-to-face diagnosis for ASD and PTSD. ...
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... Whereas previous techniques have suggested the use of model ensembles in unsupervised learning 16,20 , these methods have so far been limited to 'shallow' models with a single hidden layer. Moreover, the application of Explainable AI (XAI) in life sciences [21][22][23] , although widespread, often grapples with complex, multidimensional data. In this context, model ensembles offer a substantial advantage, improving the quality and reliability of feature attribution 24 , thereby aligning with the growing emphasis on transparency and comprehension in AI models used for biological data analysis. ...
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Posttraumatic stress responses are characterized by a heterogeneity in clinical appearance and etiology. This heterogeneity impacts the field's ability to characterize, predict, and remediate maladaptive responses to trauma. Machine learning (ML) approaches are increasingly utilized to overcome this foundational problem in characterization, prediction, and treatment selection across branches of medicine that have struggled with similar clinical realities of heterogeneity in etiology and outcome, such as oncology. In this article, we review and evaluate ML approaches and applications utilized in the areas of posttraumatic stress, stress pathology, and resilience research, and present didactic information and examples to aid researchers interested in the relevance of ML to their own research. The examined studies exemplify the high potential of ML approaches to build accurate predictive and diagnostic models of posttraumatic stress and stress pathology risk based on diverse sources of available information. The use of ML approaches to integrate high-dimensional data demonstrates substantial gains in risk prediction even when the sources of data are the same as those used in traditional predictive models. This area of research will greatly benefit from collaboration and data sharing among researchers of posttraumatic stress disorder, stress pathology, and resilience. © 2019 International Society for Traumatic Stress Studies.