Effects of Glasgow Outcome Scale misclassification on traumatic brain injury clinical trials

Predictive power of the eTBI score for 30 day outcome in elderly patients with traumatic brain Injury

Traumatic brain injury (TBI) is a common problem in elderly individuals, with significant morbidity and mortality. The elderly Traumatic Brain Injury (eTBI) score, a novel tool for predicting outcomes in elderly patients with TBI, has shown promising results in previous studies. This study aimed to validate the eTBI score in a larger cohort of elderly patients with TBI in the Middle East. We conducted a retrospective study on 337 TBI patients with a mean age of 73.04 ± 8.73, admitted to a tertiary care hospital between March 2021 and November 2022. Within 30 days of admission, the patients' conditions, including mortality and entering a vegetative state, were evaluated. The study population was split into three groups based on eTBI score: low, medium, and high risk; then patients were divided into two subgroups based on their Glasgow Outcome Scale (GOS ≤ 2, GOS > 2) in 30 days from hospital admission. Poor outcomes (mortality and entering a vegetative state) occurred in 24.3% of the study population. Within 30 days of hospital admission, 88% of low-risk patients experienced some degree of improvement, while 100% of high-risk patients died or fell into a vegetative state. In the medium-risk group, there was a significant correlation between unresponsive pupil (P = 0.006), initial GCS score (P = 0.003), need for a ventilator device (P = 0.015), need for surgical treatment (P = 0.031) and poor outcomes. Despite having a low sensitivity (21% vs. 57%), the eTBI score performed well in terms of accuracy (81% vs. 88%), specificity (100 vs. 98%), positive predictive value (100% vs. 90%), and negative predictive value (80% vs. 88%) for both eTBI ≤ 0 and eTBI ≤ 3 thresholds. The eTBI score is a reliable tool for predicting outcomes in elderly patients with TBI. This scoring system has a positive predictive value of 100% in the eTBI ≤ 0 group, which shows that 100% of the patients who are predicted by the eTBI score to have a poor outcome will indeed have a poor outcome. Patients in the high-risk group should be closely monitored and provided with intensive care, while those in the low-risk group can be reassured about their prognosis. The eTBI score can also be used in conjunction with other clinical factors to inform treatment decisions for patients in the medium-risk group.

Fluid-Based Protein Biomarkers in Traumatic Brain Injury: The View from the Bedside

There has been an explosion of research into biofluid (blood, cerebrospinal fluid, CSF)-based protein biomarkers in traumatic brain injury (TBI) over the past decade. The availability of very large datasets, such as CENTRE-TBI and TRACK-TBI, allows for correlation of blood- and CSF-based molecular (protein), radiological (structural) and clinical (physiological) marker data to adverse clinical outcomes. The quality of a given biomarker has often been framed in relation to the predictive power on the outcome quantified from the area under the Receiver Operating Characteristic (ROC) curve. However, this does not in itself provide clinical utility but reflects a statistical association in any given population between one or more variables and clinical outcome. It is not currently established how to incorporate and integrate biofluid-based biomarker data into patient management because there is no standardized role for such data in clinical decision making. We review the current status of biomarker research and discuss how we can integrate existing markers into current clinical practice and what additional biomarkers do we need to improve diagnoses and to guide therapy and to assess treatment efficacy. Furthermore, we argue for employing machine learning (ML) capabilities to integrate the protein biomarker data with other established, routinely used clinical diagnostic tools, to provide the clinician with actionable information to guide medical intervention.

ApoE Mimetic Peptides as Therapy for Traumatic Brain Injury

The lack of targeted therapies for traumatic brain injury (TBI) remains a compelling clinical unmet need. Although knowledge of the pathophysiologic cascades involved in TBI has expanded rapidly, the development of novel pharmacological therapies has remained largely stagnant. Difficulties in creating animal models that recapitulate the different facets of clinical TBI pathology and flaws in the design of clinical trials have contributed to the ongoing failures in neuroprotective drug development. Furthermore, multiple pathophysiological mechanisms initiated early after TBI that progress in the subacute and chronic setting may limit the potential of traditional approaches that target a specific cellular pathway for acute therapeutic intervention. We describe a reverse translational approach that focuses on translating endogenous mechanisms known to influence outcomes after TBI to develop druggable targets. In particular, numerous clinical observations have demonstrated an association between apolipoprotein E (apoE) polymorphism and functional recovery after brain injury. ApoE has been shown to mitigate the response to acute brain injury by exerting immunomodulatory properties that reduce secondary tissue injury as well as protecting neurons from excitotoxicity. CN-105 represents an apoE mimetic peptide that can effectively penetrate the CNS compartment and retains the neuroprotective properties of the intact protein.

Validity of Glasgow outcome scale-extended (GOSE) mobile application for assessment of outcome in traumatic brain injury patients

PURPOSE

To develop the Glasgow Outcome Scale-Extended (GOSE) mobile application and examine the validity of the application against GOSE scoring based on traditional interview method.

METHODS

Concurrent validity was determined by comparing two independent raters' scoring for GOSE of 102 patients with traumatic brain injury, who had attended outpatient department of a tertiary neuro hospital. Agreement was assessed between the traditional interview-based pen and paper scoring and algorithm based mobile application scoring of GOSE.

RESULTS

Agreement was tested using Cohen's kappa, and the analysis revealed near perfect agreement between two raters (0.89) (p < 0.01).

CONCLUSION

The GOSE mobile application can measure GOSE Score similar to the traditional interview method. This application may help fasten the process of assessing outcome in TBI patients in clinical practice and in research.

Cognitive impairment in people living with HIV: consensus recommendations for a new approach

Current approaches to classifying cognitive impairment in people living with HIV can overestimate disease burden and lead to ambiguity around disease mechanisms. The 2007 criteria for HIV-associated neurocognitive disorders (HAND), sometimes called the Frascati criteria, can falsely classify over 20% of cognitively healthy individuals as having cognitive impairment. Minimum criteria for HAND are met on the basis of performance on cognitive tests alone, which might not be appropriate for populations with diverse educational and socioeconomic backgrounds. Imprecise phenotyping of cognitive impairment can limit mechanistic research, biomarker discovery and treatment trials. Importantly, overestimation of cognitive impairment carries the risk of creating fear among people living with HIV and worsening stigma and discrimination towards these individuals. To address this issue, we established the International HIV-Cognition Working Group, which is globally representative and involves the community of people living with HIV. We reached consensus on six recommendations towards a new approach for diagnosis and classification of cognitive impairment in people living with HIV, intended to focus discussion and debate going forward. We propose the conceptual separation of HIV-associated brain injury - including active or pretreatment legacy damage - from other causes of brain injury occurring in people living with HIV. We suggest moving away from a quantitative neuropsychological approach towards an emphasis on clinical context. Our recommendations are intended to better represent the changing profile of cognitive impairment in people living with HIV in diverse global settings and to provide a clearer framework of classification for clinical management and research studies.

Improving the Precision of the Glasgow Outcome Scale-Extended Using Item Response Theory: A TRACK-TBI Study

The Glasgow Outcome Scale-Extended (GOSE) is a functional outcome measure intended to place individuals with traumatic brain injury (TBI) into one of eight broad levels of injury-related disability. This simplicity is not always optimal, particularly when more granular assessment of individuals' injury recovery is desired. The GOSE, however, is customarily assessed using a multi-question interview that contains richer information than is reflected in the GOSE score. Using data from the multi-center Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study (N = 1544), we used item response theory (IRT) to evaluate whether rescoring the GOSE using IRT, which posits that a continuous latent variable (disability) underlies responses, can yield a more precise index of injury-related functional limitations. We fit IRT models to GOSE interview responses collected at three months post-injury. Each participant's level of functional limitation was estimated from the model (GOSE-IRT) and comparisons were made between IRT-based and standard (GOSE-Ordinal) scores. The IRT scoring resulted in 141 possible scores (vs. 7 GOSE-Ordinal scores in this sample of individuals with GOSE scores ranging between 2 and 8). Moreover, GOSE-IRT scores were significantly more strongly associated with measures of TBI-related symptoms, psychological symptoms, and quality of life. Our findings demonstrate that rescoring the GOSE interview using IRT yields more granular, meaningful measurement of injury-related functional limitations, while adding no additional respondent or examiner burden. This technique may have utility for many applications, such as clinical trials aiming to detect small treatment effects, and small-scale studies that need to maximize statistical efficiency.

Association between Scene Time Interval and Survival in EMS-Treated Major Trauma Admitted to the Intensive Care Unit: A Multinational, Multicenter Observational Study

Objective: Major trauma is a major concern in public health and a leading cause of mortality worldwide. This study aimed to evaluate the association between the prehospital scene time interval (STI) and survival in emergency medical service (EMS)-assessed major trauma patients admitted to the intensive care unit (ICU). Methods: A retrospective observational study using the Pan-Asian Trauma Outcomes Study (PATOS) database was conducted. Adult trauma patients with injury severity scores (ISSs) greater than 15 who were admitted to the ICU were selected. EMS STIs were categorized into three groups: short (0-8 minutes), intermediate (9-16 minutes), and long (over 16 minutes). The primary outcome was survival to hospital discharge, and the secondary outcome was good neurological outcome at hospital discharge. Multivariable logistic regression analysis was conducted to calculate odds ratios and confidence intervals, adjusting for age, sex, mechanism of injury, prehospital alertness, prehospital shock index, response time interval, and EMS intervention (airway, oxygen supplementation, and intravenous fluid administration). Sensitivity analysis for patients who underwent surgery or nontraumatic brain injury cases and interaction analysis by EMS intervention were performed. Results: Data from a total of 1,874 eligible patients were analyzed. Intermediate and long STIs showed significant associations with outcomes, with adjusted ORs (95% CI) of 1.21 (1.07-1.38) in the intermediate STI group and 1.74 (1.55-1.96) in the long STI group for survival and 1.37 (1.32-1.40) in the intermediate STI group and 1.31 (1.22-1.41) in the long STI group for neurological outcome. In the sensitivity analysis, the highest ORs were found in the intermediate STI group, with adjusted ORs (95% CI) of 1.40 (1.37-1.42) for survival and 1.32 (1.26-1.38) for neurological outcome. In the interaction analysis, EMS intervention showed a positive interaction effect with an intermediate STI on survival. Conclusion: In EMS-assessed adult major trauma patients admitted to the ICU, we found significant associations between STIs longer than 8 minutes and outcomes. EMS intervention has a positive interaction effect with an intermediate STI on survival. More research is needed to understand the implications of practice for major trauma in the field.

Added Value of a Blinded Outcome Adjudication Committee in an Open-Label Randomized Stroke Trial

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Blinded outcome assessment in trials with prospective randomized open blinded end point design is challenging. Unblinding can result in misclassified outcomes and biased treatment effect estimates. An outcome adjudication committee assures blinded outcome assessment, but the added value for trials with prospective randomized open blinded end point design and subjective outcomes is unknown. We aimed to assess the degree of misclassification of modified Rankin Scale (mRS) scores by a central assessor and its impact on treatment effect estimates in a stroke trial with prospective randomized open blinded end point design.

Central Curation of Glasgow Outcome Scale-Extended Data: Lessons Learned from TRACK-TBI

The Glasgow Outcome Scale (GOS) in its original or extended (GOSE) form is the most widely used assessment of global disability in traumatic brain injury (TBI) research. Several publications have reported concerns about assessor scoring inconsistencies, but without documentation of contributing factors. We reviewed 6801 GOSE assessments collected longitudinally, across 18 sites in the 5-year, observational Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study. We recorded error rates (i.e., corrections to a section or an overall rating) based on site assessor documentation and categorized scoring issues, which then informed further training. In cohort 1 (n = 1261; February 2014 to May 2016), 24% of GOSEs had errors identified by central review. In cohort 2 (n = 1130; June 2016 to July 2018), acquired after curation of cohort 1 data, feedback, and further training of site assessors, the error rate was reduced to 10%. GOSE sections associated with the most frequent interpretation and scoring difficulties included whether current functioning represented a change from pre-injury (466 corrected ratings in cohort 1; 62 in cohort 2), defining dependency in the home and community (163 corrections in cohort 1; three in cohort 2) and return to work/school (72 corrections in cohort 1; 35 in cohort 2). These results highlight the importance of central review in improving consistency across sites and over time. Establishing clear scoring criteria, coupled with ongoing guidance and feedback to data collectors, is essential to avoid scoring errors and resultant misclassification, which carry potential to result in "failure" of clinical trials that rely on the GOSE as their primary outcome measure.

Ordinal outcome analysis improves the detection of between-hospital differences in outcome

Background

There is a growing interest in assessment of the quality of hospital care, based on outcome measures. Many quality of care comparisons rely on binary outcomes, for example mortality rates. Due to low numbers, the observed differences in outcome are partly subject to chance. We aimed to quantify the gain in efficiency by ordinal instead of binary outcome analyses for hospital comparisons. We analyzed patients with traumatic brain injury (TBI) and stroke as examples.

Methods

We sampled patients from two trials. We simulated ordinal and dichotomous outcomes based on the modified Rankin Scale (stroke) and Glasgow Outcome Scale (TBI) in scenarios with and without true differences between hospitals in outcome. The potential efficiency gain of ordinal outcomes, analyzed with ordinal logistic regression, compared to dichotomous outcomes, analyzed with binary logistic regression was expressed as the possible reduction in sample size while keeping the same statistical power to detect outliers.

Results

In the IMPACT study (9578 patients in 265 hospitals, mean number of patients per hospital = 36), the analysis of the ordinal scale rather than the dichotomized scale (‘unfavorable outcome’), allowed for up to 32% less patients in the analysis without a loss of power. In the PRACTISE trial (1657 patients in 12 hospitals, mean number of patients per hospital = 138), ordinal analysis allowed for 13% less patients. Compared to mortality, ordinal outcome analyses allowed for up to 37 to 63% less patients.

Conclusions

Ordinal analyses provide the statistical power of substantially larger studies which have been analyzed with dichotomization of endpoints. We advise to exploit ordinal outcome measures for hospital comparisons, in order to increase efficiency in quality of care measurements.

Trial registration

We do not report the results of a health care intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-020-01185-7.

Inflammasome Caspase-1 Activity is Elevated in Cerebrospinal Fluid After Aneurysmal Subarachnoid Hemorrhage and Predicts Functional Outcome

BACKGROUND/OBJECTIVE

Subarachnoid hemorrhage (SAH) is a devastating neurological injury, further complicated by few available methods to objectively predict outcomes. With the recent shift in focus to neuroinflammation as a potential cause of adverse outcomes following SAH, we investigated the inflammasome-derived enzyme, caspase-1, as a potential biomarker for poor functional outcome.

METHODS

SAH patients were recruited from a regional stroke referral center. Cerebrospinal fluid (CSF) samples from 18 SAH subjects were collected via an external ventricular drain and obtained as close as possible to admission (within 72 h). For control subjects, we collected CSF from 9 patients undergoing lumbar puncture with normal CSF. Caspase-1 activity was measured using commercially available luminescence assays. SAH subjects were categorized at hospital discharge into those with good outcomes (Glasgow Outcome Scale, GOS, of 4-5) and poor outcomes (GOS of 1-3).

RESULTS

CSF analysis demonstrated a nearly seven-fold increase in caspase-1 activity in SAH patients compared to controls (p < 0.0001). Within the SAH group, 10 patients (55.6%) had good outcomes and 8 patients (44.4%) had poor outcomes. Mean caspase-1 activity in the poor outcome group was approximately three-times higher than the good outcome group (p = 0.001). Caspase-1 activity was significantly correlated with GOS score (r = - 0.705, p = 0.001). Receiver operating characteristic curve analysis showed that caspase-1 activity can accurately differentiate between patients with good versus poor functional outcome (area under the curve 0.944, p = 0.002).

CONCLUSIONS

Inflammasome-derived caspase-1 activity is elevated in the CSF of SAH patients compared to controls and higher levels correlate with worse functional outcome.

Ventriculoperitoneal shunt insertion in human immunodeficiency virus infected adults: a systematic review and meta-analysis

BACKGROUND

Hydrocephalus is a common, life threatening complication of human immunodeficiency virus (HIV)-related central nervous system opportunistic infection which can be treated by insertion of a ventriculoperitoneal shunt (VPS). In HIV-infected patients there is concern that VPS might be associated with unacceptably high mortality. To identify prognostic indicators, we aimed to compare survival and clinical outcome following VPS placement between all studied causes of hydrocephalus in HIV infected patients.

METHODS

The following electronic databases were searched: The Cochrane Central Register of Controlled Trials, MEDLINE (PubMed), EMBASE, CINAHL Plus, LILACS, Research Registry, the metaRegister of Controlled Trials, ClinicalTrials.gov, African Journals Online, and the OpenGrey database. We included observational studies of HIV-infected patients treated with VPS which reported of survival or clinical outcome. Data was extracted using standardised proformas. Risk of bias was assessed using validated domain-based tools.

RESULTS

Seven Hunderd twenty-three unique study records were screened. Nine observational studies were included. Three included a total of 75 patients with tuberculous meningitis (TBM) and six included a total of 49 patients with cryptococcal meningitis (CM). All of the CM and two of the TBM studies were of weak quality. One of the TBM studies was of moderate quality. One-month mortality ranged from 62.5-100% for CM and 33.3-61.9% for TBM. These pooled data were of low to very-low quality and was inadequate to support meta-analysis between aetiologies. Pooling of results from two studies with a total of 77 participants indicated that HIV-infected patients with TBM had higher risk of one-month mortality compared with HIV non-infected controls (odds ratio 3.03; 95% confidence-interval 1.13-8.12; p = 0.03).

CONCLUSIONS

The evidence base is currently inadequate to inform prognostication in VPS insertion in HIV-infected patients. A population-based prospective cohort study is required to address this, in the first instance.

Recovery in cognitive motor dissociation after severe brain injury: A cohort study

OBJECTIVE

To investigate the functional and cognitive outcomes during early intensive neurorehabilitation and to compare the recovery patterns of patients presenting with cognitive motor dissociation (CMD), disorders of consciousness (DOC) and non-DOC.

METHODS

We conducted a single center observational cohort study of 141 patients with severe acquired brain injury, consecutively admitted to an acute neurorehabilitation unit. We divided patients into three groups according to initial neurobehavioral diagnosis at admission using the Coma Recovery Scale-Revised (CRS-R) and the Motor Behavior Tool (MBT): potential clinical CMD, [N = 105]; DOC [N = 19]; non-DOC [N = 17]). Functional and cognitive outcomes were assessed at admission and discharge using the Glasgow Outcome Scale, the Early Rehabilitation Barthel Index, the Disability Rating Scale, the Rancho Los Amigos Levels of Cognitive Functioning, the Functional Ambulation Classification Scale and the modified Rankin Scale. Confirmed recovery of conscious awareness was based on CRS-R criteria.

RESULTS

CMD patients were significantly associated with better functional outcomes and potential for improvement than DOC. Furthermore, outcomes of CMD patients did not differ significantly from those of non-DOC. Using the CRS-R scale only; approximatively 30% of CMD patients did not recover consciousness at discharge.

INTERPRETATION

Our findings support the fact that patients presenting with CMD condition constitute a separate category, with different potential for improvement and functional outcomes than patients suffering from DOC. This reinforces the need for CMD to be urgently recognized, as it may directly affect patient care, influencing life-or-death decisions.

The Relationship of the FOUR Score to Patient Outcome: A Systematic Review

The Full Outline of UnResponsiveness (FOUR) score assessment of consciousness replaces the Glasgow Coma Scale (GCS) verbal component with assessment of brainstem reflexes. A comprehensive overview studying the relationship between a patient's FOUR score and outcome is lacking. We aim to systematically review published literature reporting the relationship of FOUR score to outcome in adult patients with impaired consciousness. We systematically searched for records of relevant studies: CENTRAL, MEDLINE, EMBASE, Scopus, Web of Science, ClinicalTrials.gov, and OpenGrey. Prospective, observational studies of patients with impaired consciousness were included where consciousness was assessed using FOUR score, and where the outcome in mortality or validated functional outcome scores was reported. Consensus-based screening and quality appraisal were performed. Outcome prognostication was synthesized narratively. Forty records (37 studies) were identified, with overall low (n = 2), moderate (n = 25), or high (n = 13) risk of bias. There was significant heterogeneity in patient characteristics. FOUR score showed good to excellent prognostication of in-hospital mortality in most studies (area under curve [AUC], >0.80). It was good at predicting poor functional outcome (AUC, 0.80–0.90). There was some evidence that motor and eye components (also GCS components) had better prognostic ability than brainstem components. Overall, FOUR score relates closely to in-hospital mortality and poor functional outcome. More studies with standardized design are needed to better characterize it in different patient groups, confirm the differences between its four components, and compare it with the performance of GCS and its recently described derivative, the GCS-Pupils, which includes pupil response as a fourth component.

Diagnosing the GOSE: Structural and Psychometric Properties Using Item Response Theory, a TRACK-TBI Pilot Study

The Glasgow Outcome Scale-Extended (GOSE) was designed to assess global outcome after traumatic brain injury (TBI). Since its introduction, several empirically founded criticisms of the GOSE have been raised, including poor reliability; an insensitivity to small, but potentially meaningful, changes; a tendency to produce ceiling effects; inconsistent associations with neurocognitive, psychological, and quality-of-life measures; and an inability to assess the multi-dimensional nature of TBI outcome. The current project took a diagnostic approach to identifying the underlying causes of reported limitations by exploring the internal construct validity of the GOSE at 3 and 6 months post-injury using item response theory (IRT) techniques. Data were from the TRACK-TBI Pilot Study, a large (N = 586), prospective, multi-site project that included TBI cases of all injury severity levels. To assess the level of latent functional "impairment" captured by GOSE items independent of the assigned outcome category or GOSE total score, items were modified so that higher scores reflected greater impairment. Results showed that although the GOSE's items capture varying levels of impairment across a broad disability spectrum at 3 and 6 months, there was also evidence at each time point of item redundancy (multiple items capturing similar levels of impairment), item deficiency (lack of items capturing lower levels of impairment), and item inefficiency (items only capturing minimal impairment information). The findings illustrate the value of IRT to illuminate strengths and weaknesses of clinical outcome assessment measures and provide a framework for future measure refinement.

Glasgow Outcome Scale Measures and Impact on Analysis and Results of a Randomized Clinical Trial of Severe Traumatic Brain Injury

The original unstructured Glasgow Outcome Scale (uGOS) and the newer structured interviews GOS and the Extended GOS (GOS-E) have been used widely as outcomes in severe traumatic brain injury (TBI) trials. We compared outcome categories (ranging from dead [D] to good recovery [GR]) for each measure in a randomized trial of transfusion threshold and the implications of measure choice and analysis methods for the results of the trial. We planned to explore patient symptomology possibly driving any discrepancies between the patient's uGOS and GOS scores. Category correspondence between uGOS and GOS scores occurred in 160 (88.4%) of the 181 analyzed cases. The GOS-E and GOS instruments incorporated more behavioral/cognitive/social and other components, leading to a worse outcome in some cases than for the uGOS. Choice of outcome measure and analysis led to incongruous conclusions. Dichotomizing uGOS into favorable outcome (GR and moderate disability [MD] categories) versus unfavorable (severe disability [SD], vegetative state [VS], and D categories), we observed a significant effect of transfusion threshold (odds ratio [OR] = 0.51, p = 0.03; adjusted OR = 0.40, p = 0.02). For the same dichotomization of GOS and GOS-E, the effect was not statistically significant but the ORs were similar (ORs between 0.57 and 0.68, p > 0.15 for all). An effect was not detected using ordinal logistic regression or sliding dichotomy method for all three measures. Differences in categorizations of subjects between moderate and severe disability among the scales impacted conclusions of the trial. In future studies, particular attention should be given to implementing GOS measures and describing the methodology for how outcomes were ascertained.

PROBAST: A Tool to Assess Risk of Bias and Applicability of Prediction Model Studies: Explanation and Elaboration

Prediction models in health care use predictors to estimate for an individual the probability that a condition or disease is already present (diagnostic model) or will occur in the future (prognostic model). Publications on prediction models have become more common in recent years, and competing prediction models frequently exist for the same outcome or target population. Health care providers, guideline developers, and policymakers are often unsure which model to use or recommend, and in which persons or settings. Hence, systematic reviews of these studies are increasingly demanded, required, and performed. A key part of a systematic review of prediction models is examination of risk of bias and applicability to the intended population and setting. To help reviewers with this process, the authors developed PROBAST (Prediction model Risk Of Bias ASsessment Tool) for studies developing, validating, or updating (for example, extending) prediction models, both diagnostic and prognostic. PROBAST was developed through a consensus process involving a group of experts in the field. It includes 20 signaling questions across 4 domains (participants, predictors, outcome, and analysis). This explanation and elaboration document describes the rationale for including each domain and signaling question and guides researchers, reviewers, readers, and guideline developers in how to use them to assess risk of bias and applicability concerns. All concepts are illustrated with published examples across different topics. The latest version of the PROBAST checklist, accompanying documents, and filled-in examples can be downloaded from www.probast.org.

Pre-Clinical Testing of Therapies for Traumatic Brain Injury

Despite the large number of promising neuroprotective agents identified in experimental traumatic brain injury (TBI) studies, none has yet shown meaningful improvements in long-term outcome in clinical trials. To develop recommendations and guidelines for pre-clinical testing of pharmacological or biological therapies for TBI, the Moody Project for Translational Traumatic Brain Injury Research hosted a symposium attended by investigators with extensive experience in pre-clinical TBI testing. The symposium participants discussed issues related to pre-clinical TBI testing including experimental models, therapy and outcome selection, study design, data analysis, and dissemination. Consensus recommendations included the creation of a manual of standard operating procedures with sufficiently detailed descriptions of modeling and outcome measurement procedures to permit replication. The importance of the selection of clinically relevant outcome variables, especially related to behavior testing, was noted. Considering the heterogeneous nature of human TBI, evidence of therapeutic efficacy in multiple, diverse (e.g., diffuse vs. focused) rodent models and a species with a gyrencephalic brain prior to clinical testing was encouraged. Basing drug doses, times, and routes of administration on pharmacokinetic and pharmacodynamic data in the test species was recommended. Symposium participants agreed that the publication of negative results would reduce costly and unnecessary duplication of unsuccessful experiments. Although some of the recommendations are more relevant to multi-center, multi-investigator collaborations, most are applicable to pre-clinical therapy testing in general. The goal of these consensus guidelines is to increase the likelihood that therapies that improve outcomes in pre-clinical studies will also improve outcomes in TBI patients.

Repurposing and repositioning neurosteroids in the treatment of traumatic brain injury: A report from the trenches

The field of neuroprotection after brain injuries has been littered with failed clinical trials. Finding a safe and effective treatment for acute traumatic brain injury remains a serious unmet medical need. Repurposing drugs that have been in use for other disorders is receiving increasing attention as a strategy to move candidate drugs more quickly to trial while reducing the very high cost of new drug development. This paper describes our own serendipitous discovery of progesterone's neuroprotective potential, and the strategies we are using in repurposing and developing this hormone for use in brain injuries-applications very different from its classical uses in treating disorders of the reproductive system. We have been screening and testing a novel analog that maintains progesterone's therapeutic properties while overcoming its physiochemical challenges, and testing progesterone in combination treatment with another pleiotropic hormone, vitamin D. Finally, our paper, in the context of the problems and pitfalls we have encountered, surveys some of the factors we found to be critical in the clinical translation of repurposed drugs. This article is part of the Special Issue entitled 'Drug Repurposing: old molecules, new ways to fast track drug discovery and development for CNS disorders'.

Validating Multidimensional Outcome Assessment Using the TBI Common Data Elements: An Analysis of the TRACK-TBI Pilot Sample

The Glasgow Outcome Scale-Extended (GOSE) is often the primary outcome measure in clinical trials for traumatic brain injury (TBI). Although the GOSE's capture of global function outcome has several strengths, concerns have been raised about its limited ability to identify mild disability and failure to capture the full scope of problems patients exhibit after TBI. This analysis examined the convergence of disability ratings across a multidimensional set of outcome domains in the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) Pilot study. The study collected measures recommended by the TBI Common Data Elements (CDE) Workgroup. Patients presenting to 3 emergency departments with a TBI of any severity enrolled in TRACK-TBI prospectively after injury; outcome measures were collected at 3 and six months postinjury. Analyses examined frequency of impairment and overlap between impairment status across the CDE outcome domains of Global Level of Functioning (GOSE), Neuropsychological (cognitive) Impairment, Psychological Status, TBI Symptoms, and Quality of Life. GOSE score correlated in the expected direction with other outcomes (M Spearman's rho = .21 and .49 with neurocognitive and self-report outcomes, respectively). The subsample in the Upper Good Recovery (GOSE 8) category appeared quite healthy across most other outcomes, although 19.0% had impaired executive functioning (Trail Making Test Part B). A significant minority of participants in the Lower Good Recovery subgroup (GOSE 7) met criteria for impairment across numerous other outcome measures. The findings highlight the multidimensional nature of TBI recovery and the limitations of applying only a single outcome measure.

Injury severity measures for predicting return-to-work after a traumatic brain injury

This study compared the ability of five injury severity measures, namely the Abbreviated Injury Scale to the Head (AIS-H), Glasgow Coma Scale (GCS), Glasgow Outcome Scale (GOS), Extended Glasgow Outcome Scale (GOSE), and Injury Severity Score (ISS), to predict return-to-work after a traumatic brain injury (TBI). Furthermore, factors potentially associated with return-to-work were investigated. In total, 207 individuals aged ≤65 years newly diagnosed with a TBI and employed at the time of injury were recruited and followed-up for 1year by telephone every 3 months. A bivariate proportional hazards model analysis revealed that all five injury severity measures were significantly associated with return-to-work after a TBI. The AIS-H and non-head ISS explained 23.8% of the variation in the duration of returning to work from discharge after hospitalization for a TBI; similarly, the GCS, GOS, GOSE, and ISS respectively accounted for 4.7%, 21.4%, 12.9%, and 48.4% of the variation. A multivariable analysis revealed that individuals with higher injury severity as measured by the ISS (hazard ratio [HR], 0.94; 95% confidence interval [CI], 0.92-0.97), a lack of autonomy in transportation (HR, 2.55; 95% CI, 1.23-5.32), cognitive impairment (HR, 0.47; 95% CI, 0.28-0.79), and depression (HR, 0.97; 95% CI, 0.95-0.99) were significantly less likely to be employed after a TBI. In conclusion, of the five injury severity measures, the ISS may be the most capable measure of predicting return-to-work after a TBI. In addition to injury severity, autonomy in transportation, cognitive function, and the depressive status may also influence the employment status during the first year after a TBI.

Past, Present, and Future of Traumatic Brain Injury Research

Traumatic brain injury (TBI) is the greatest cause of death and severe disability in young adults; its incidence is increasing in the elderly and in the developing world. Outcome from severe TBI has improved dramatically as a result of advancements in trauma systems and supportive critical care, however we remain without a therapeutic which acts directly to attenuate brain injury. Recognition of secondary injury and its molecular mediators has raised hopes for such targeted treatments. Unfortunately, over 30 late-phase clinical trials investigating promising agents have failed to translate a therapeutic for clinical use. Numerous explanations for this failure have been postulated and are reviewed here. With this historical context we review ongoing research and anticipated future trends which are armed with lessons from past trials, new scientific advances, as well as improved research infrastructure and funding. There is great hope that these new efforts will finally lead to an effective therapeutic for TBI as well as better clinical management strategies.

The Glasgow Outcome Scale - 40 years of application and refinement

The Glasgow Outcome Scale (GOS) was first published in 1975 by Bryan Jennett and Michael Bond. With over 4,000 citations to the original paper, it is the most highly cited outcome measure in studies of brain injury and the second most-cited paper in clinical neurosurgery. The original GOS and the subsequently developed extended GOS (GOSE) are recommended by several national bodies as the outcome measure for major trauma and for head injury. The enduring appeal of the GOS is linked to its simplicity, short administration time, reliability and validity, stability, flexibility of administration (face-to-face, over the telephone and by post), cost-free availability and ease of access. These benefits apply to other derivatives of the scale, including the Glasgow Outcome at Discharge Scale (GODS) and the GOS paediatric revision. The GOS was devised to provide an overview of outcome and to focus on social recovery. Since the initial development of the GOS, there has been an increasing focus on the multidimensional nature of outcome after head injury. This Review charts the development of the GOS, its refinement and usage over the past 40 years, and considers its current and future roles in developing an understanding of brain injury.

Progesterone neuroprotection: The background of clinical trial failure

Since the first pioneering studies in the 1990s, a large number of experimental animal studies have demonstrated the neuroprotective efficacy of progesterone for brain disorders, including traumatic brain injury (TBI). In addition, this steroid has major assets: it easily crosses the blood-brain-barrier, rapidly diffuses throughout the brain and exerts multiple beneficial effects by acting on many molecular and cellular targets. Moreover, progesterone therapies are well tolerated. Notably, increased brain levels of progesterone are part of endogenous neuroprotective responses to injury. The hormone thus emerged as a particularly promising protective candidate for TBI and stroke patients. The positive outcomes of small Phase 2 trials aimed at testing the safety and potential protective efficacy of progesterone in TBI patients then provided support and guidance for two large, multicenter, randomized and placebo-controlled Phase 3 trials, with more than 2000 TBI patients enrolled. The negative outcomes of both trials, named ProTECT III and SyNAPSE, came as a big disappointment. If these trials were successful, progesterone would have become the first efficient neuroprotective drug for brain-injured patients. Thus, progesterone has joined the numerous neuroprotective candidates that have failed in clinical trials. The aim of this review is a reappraisal of the preclinical animal studies, which provided the proof of concept for the clinical trials, and we critically examine the design of the clinical studies. We made efforts to present a balanced view of the strengths and limitations of the translational studies and of some serious issues with the clinical trials. We place particular emphasis on the translational value of animal studies and the relevance of TBI biomarkers. The probability of failure of ProTECT III and SyNAPSE was very high, and we present them within the broader context of other unsuccessful trials.

Inter-rater agreement on assessment of outcome within a trauma registry

INTRODUCTION

To better evaluate the degree of ongoing disability in trauma patients, it has been recommended that trauma registries introduce routine long-term outcome measurement. One of the measures recommended for use is the Extended Glasgow Outcome Scale (GOS-E). However, few registries have adopted this measure and further research is required to determine its reliability with trauma populations. This study aimed to evaluate the inter-rater agreement of GOS-E scoring between an expert rater and trauma registry follow-up staff with a sample of detailed trauma case scenarios.

METHODS

Sixteen trauma registry telephone interviewers participated in the study. They were provided with a written summary of 15 theoretical adult trauma cases covering a spectrum of disability and asked to rate each case using the structured GOS-E interview. Their ratings were compared with those of an expert rater in order to calculate the inter-rater agreement for each individual rater-expert rater pair. Agreement was reported as the percentage of agreement, the kappa statistic, and weighted kappa. A multi-rater kappa value was also calculated for agreement between the 16 raters.

RESULTS

Across the 15 cases, the percentage of agreement between individual raters and the expert ranged from 63% to 100%. Across the 16 raters, the percentage of agreement with the expert rater ranged from 73-100% (mean=90%). Kappa values ranged from 0.65 to 1.00 across raters (mean=0.86) and weighted kappa values ranged from 0.73 to 1.00 (mean=0.89) The multi-rater kappa value was 0.78 (95% CI: 0.66, 0.89).

CONCLUSIONS

Sixteen follow-up staff achieved 'substantial' to 'almost perfect' agreement with an expert rater using the GOS-E outcome measure to score 15 sample trauma cases. The results of this study lend support to the use of the GOS-E within trauma populations and highlight the importance of ongoing training where multiple raters are involved to ensure reliable outcome reporting. It is also recommended that the structured GOS-E interview guide be used to achieve better agreement between raters. Ensuring the reliability of trauma outcome scores will enable more accurate evaluation of patient outcomes, and ultimately, more targeted trauma care.

Embracing failure: What the Phase III progesterone studies can teach about TBI clinical trials

Background: Despite positive preclinical studies and two positive Phase II clinical trials, two large Phase III clinical trials of progesterone treatment of acute traumatic brain injury (TBI) recently ended with negative results, so a 100% failure rate continues to plague the field of TBI trials.

Methods: This paper reviews and analyses the trial structures and outcomes and discusses the implications of these failures for future drug and clinical trial development. Persistently negative trial outcomes have led to disinvestment in new drug research by companies and policy-makers and disappointment for patients and their families, failures which represent a major public health concern. The problem is not limited to TBI. Failure rates are high for trials in stroke, sepsis, cardiology, cancer and orthopaedics, among others.

Results: This paper discusses some of the reasons why the Phase III trials have failed. These reasons may include faulty extrapolation from pre-clinical data in designing clinical trials and the use of subjective outcome measures that accurately reflect neither the nature of the deficits nor long-term quantitative recovery.

Conclusions: Better definitions of injury and healing and better outcome measures are essential to change the embrace of failure that has dominated the field for over 30 years. This review offers suggestions to improve the situation.

Traumatic brain injury and cognition

Traumatic brain injury (TBI) is a major cause of death and disability, and therefore an important health and socioeconomic problem for our society. Individuals surviving from a moderate to severe TBI frequently suffer from long-lasting cognitive deficits. Such deficits include different aspects of cognition such as memory, attention, executive functions, and awareness of their deficits. This chapter presents a review of the main neuropsychological and neuroimaging studies of patients with TBI. These studies found that patients evolve differently according to the severity of the injury, the mechanism causing the injury, and the lesion location. Further research is necessary to develop rehabilitation methods that enhance brain plasticity and recovery after TBI. In this chapter, we summarize current knowledge and controversies, focusing on cognitive sequelae after TBI. Recommendations from the Common Data Elements are provided, with an emphasis on diagnosis, outcome measures, and studies organization to make data more comparable across studies. Final considerations on neuroimaging advances, rehabilitation approaches, and genetics are described in the final section of the chapter.

Design of acute neuroprotection studies

Traumatic brain injury (TBI) is a substantial public health problem. The discovery of progressive, ongoing damage to the brain by means of complex molecular mechanisms which follow the initial injury has raised the possibility of targeted therapeutic intervention. Despite a substantial investment in trials testing dozens of therapeutics in humans, however, to date none has demonstrated robust efficacy. Deficiencies in the design of human clinical trials is likely to explain many translational failures, at least in part. Here we review secondary injury mediators and key trials which have targeted them. We provide a thorough discussion of putative reasons why trials thus far have failed and suggestions for the design of future clinical studies. Important insights from the IMPACT study are also presented in detail; in addition to providing critical insights for future trial design and analysis it suggests that reanalysis of completed studies may reveal inappropriately discarded treatments. Unfortunately limited resources are available for translational research and it is difficult to procure funds needed for well-resourced, large and definitive studies. History suggests, however, that investing in studies that are unlikely to provide a definitive answer only serves to increase required investment as they tend to mandate further study.

Functional outcome after head injury: comparison of 12-45 year old male and female hormonally active patients

OBJECTIVES

Head injury is the leading cause of death in patients with major trauma, but little is known of post-trauma rehabilitation morbidity in Hong Kong. The purpose of this study was to identify factors affecting functional outcome in hormonally active patients 6 months after head injury.

METHODS

Secondary analysis of the trauma registry database with data collected prospectively at two trauma centres between January 2001 and December 2007. Demographic and trauma data for patients aged 12-45 years with a head Abbreviated Injury Score ≥3 were analysed. The Glasgow outcome scale (GOS) was used for assessment and was assessed 6 months after head injury. The primary outcome measure was a composite poor outcome, namely "dead, vegetative and severely disabled" measured using the GOS.

RESULTS

Of 698 patients included in the study (mean age 29 years; range 12-45 years; 75.8% male), 581 (83.2%) had a good outcome, and 117 (16.8%) met the primary outcome measure, namely a poor outcome, including 88 (12.6%) patients who died. 453 (64.9%) patients had an injury severity score (ISS) of 16-40, and 102 (14.6%) patients had an ISS>40. 220 (31.5%) patients underwent head injury related operation. The mean length of stay in the intensive care unit (ICU) was 3.9 days. Univariate analysis showed that high ISS, Emergency Department (ED) systolic blood pressure (SBP)>160mmHg or <90mmHg, respiratory rate<12/min or >24/min, low ED Glasgow Coma Score (GCS), trauma call activation, head related operation and ICU admission were related to poor outcome. Multivariate analysis showed that high ISS, low or high ED SBP and low ED GCS were related to poor functional outcome.

CONCLUSION

This study showed that ISS, ED SBP and ED GCS were related to poor functional outcome. Gender showed no statistically significant relationship with functional outcome.

New considerations in the design of clinical trials for traumatic brain injury

Randomized controlled trials in traumatic brain injury (TBI) pose several complicated methodological challenges related to the heterogeneity of the population. Several strategies have been proposed to deal with these challenges. Recommendations presented by the International Mission for Prognosis and Analysis of Clinical Trials in TBI (IMPACT) study group include the use of relatively broad enrollment criteria combined with covariate adjustment for strong predictors of outcome in the analysis phase, rather than the use of strict enrollment criteria. Furthermore, an ordinal rather than a dichotomized analysis of the Glasgow Outcome Scale - the outcome measure in most TBI trials - will increase the statistical power significantly. This review discusses the issue of heterogeneity in TBI trials and summarizes the value of different innovative methods for the design and statistical analysis of randomized controlled trials in TBI. Future directions highlight the opportunities offered by alternative strategies, such as comparative effectiveness research, to investigate the clinical benefits of established and novel therapies in TBI.

Defining glaucomatous optic neuropathy from a continuous measure of optic nerve damage - the optimal cut-off point for risk-factor analysis in population-based epidemiology

PURPOSE

Diseases characterized by a continuous trait can be defined by setting a cut-off point for the disease measure in question, accepting some misclassification. The 97.5th percentile is commonly used as a cut-off point. However, it is unclear whether this percentile is the optimal cut-off point from the point of view of risk-factor analysis. The optimal cut-off point for risk-factor analysis can be found with a statistical method that minimizes the effect of misclassification. We applied this method to glaucomatous optic neuropathy. Here, the continuous trait is the cup-disc ratio. The aim of this study was to determine the optimal cup-disc ratio cut-off point for risk-factor analysis in population-based epidemiology.

METHODS

All participants in the population-based Rotterdam Study underwent intraocular pressure (IOP) measurements, assessment of the cup-disc ratio with the Heidelberg Retina Tomograph (HRT) and visual field testing. In the statistical method, the cup-disc ratio (the continuous trait) and the IOP (a major risk factor) were independent variables and glaucomatous visual field loss (the true glaucoma endpoint) the dependent variable in a logistic regression model. The optimal cup-disc ratio cut-off point was found by minimizing the influence of IOP in this model. Variability of the approach was assessed by using a bootstrap resampling technique.

RESULTS

Of 2444 included participants, 93 had glaucomatous visual field loss. The median optimal cup-disc ratio cut-off point was the 97.0th percentile with a 95% central range from 95.5 to 98.5.

CONCLUSION

The optimal cup-disc ratio cut-off point for risk-factor analysis is close to the commonly used 97.5th percentile.

Impact of GOS misclassification on ordinal outcome analysis of traumatic brain injury clinical trials

This study extends our previous investigation regarding the effect of nondifferential dichotomous Glasgow Outcome Scale (GOS) misclassification in traumatic brain injury (TBI) clinical trials to the effect of GOS misclassification on ordinal analysis in TBI clinical trials. The impact of GOS misclassification and ordinal outcome analysis was explored via probabilistic sensitivity analyses using TBI patient datasets from the IMPACT database (n = 9205). Three patterns of misclassification were explored given the pre-specified misclassification distributions. For the random pattern, we specified a trapezoidal distribution (minimum: 80%, mode: 85%, and 95%, maximum: 100%) for both sensitivity and specificity; for the upward pattern, the same trapezoidal distribution for sensitivity but with a perfect specificity; and for the downward pattern, the same trapezoidal distribution for specificity but with a perfect sensitivity. The conventional 95% confidence intervals and simulation intervals, which accounts for the misclassification and random errors together, were reported. The results showed that given the specified misclassification distributions, the misclassification with a random or upward pattern would have caused a slightly underestimated outcome in the observed data. However, the misclassification with a downward pattern would have resulted in an inflated estimation. Thus the sensitivity analysis suggests that the nondifferential misclassification can cause uncertainties on the primary outcome estimation in TBI trials. However, such an effect is likely to be small when ordinal analysis is applied, compared with the impact of dichotomous GOS misclassifications. The result underlines that the ordinal GOS analysis may gain from both statistical efficiency, as suggested by several recent studies, and a relatively smaller impact from misclassification as compared with conventional binary GOS analysis.

Measuring outcome in traumatic brain injury treatment trials: recommendations from the traumatic brain injury clinical trials network

BACKGROUND

Traumatic brain injury (TBI) involves several aspects of a patient's condition, including physical, mental, emotional, cognitive, social, and functional changes. Therefore, a clinical trial with individuals with TBI should consider outcome measures that reflect their global status.

METHODS

We present the work of the National Institute of Child Health and Development-sponsored Traumatic Brain Injury Clinical Trials Network Outcome Measures subcommittee and its choice of outcome measures for a phase III clinical trial of patients with complicated mild to severe TBI.

RESULTS

On the basis of theoretical and practical considerations, the subcommittee recommended the adoption of a core of 9 measures that cover 2 different areas of recovery: functional and cognitive. These measures are the Extended Glasgow Outcome Scale; the Controlled Oral Word Association Test; the Trail Making Test, Parts A and B; the California Verbal Learning Test-II; the Wechsler Adult Intelligence Scale-III Digit Span subtest; the Wechsler Adult Intelligence Scale-III Processing Speed Index; and the Stroop Color-Word Matching Test, Parts 1 and 2.

CONCLUSIONS

The statistical methods proposed to analyze these measures using a global test procedure, along with research and methodological and regulatory issues involved with the use of multiple outcomes in a clinical trial, are discussed.

Recommendations for the use of common outcome measures in traumatic brain injury research

This article summarizes the selection of outcome measures by the interagency Traumatic Brain Injury (TBI) Outcomes Workgroup to address primary clinical research objectives, including documentation of the natural course of recovery from TBI, prediction of later outcome, measurement of treatment effects, and comparison of outcomes across studies. Consistent with other Common Data Elements Workgroups, the TBI Outcomes Workgroup adopted the standard 3-tier system in its selection of measures. In the first tier, core measures included valid, robust, and widely applicable outcome measures with proven utility in TBI from each identified domain, including global level of function, neuropsychological impairment, psychological status, TBI-related symptoms, executive functions, cognitive and physical activity limitations, social role participation, and perceived health-related quality of life. In the second tier, supplemental measures were recommended for consideration in TBI research focusing on specific topics or populations. In the third tier, emerging measures included important instruments currently under development, in the process of validation, or nearing the point of published findings that have significant potential to be superior to some older ("legacy") measures in the core and supplemental lists and may eventually replace them as evidence for their utility emerges.

A method for reducing misclassification in the extended Glasgow Outcome Score

The eight-point extended Glasgow Outcome Scale (GOSE) is commonly used as the primary outcome measure in traumatic brain injury (TBI) clinical trials. The outcome is conventionally collected through a structured interview with the patient alone or together with a caretaker. Despite the fact that using the structured interview questionnaires helps reach agreement in GOSE assessment between raters, significant variation remains among different raters. We introduce an alternate GOSE rating system as an aid in determining GOSE scores, with the objective of reducing inter-rater variation in the primary outcome assessment in TBI trials. Forty-five trauma centers were randomly assigned to three groups to assess GOSE scores on sample cases, using the alternative GOSE rating system coupled with central quality control (Group 1), the alternative system alone (Group 2), or conventional structured interviews (Group 3). The inter-rater variation between an expert and untrained raters was assessed for each group and reported through raw agreement and with weighted kappa (kappa) statistics. Groups 2 and 3 without central review yielded inter-rater agreements of 83% (weighted kappa = 0.81; 95% CI 0.69, 0.92) and 83% (weighted kappa = 0.76, 95% CI 0.63, 0.89), respectively, in GOS scores. In GOSE, the groups had an agreement of 76% (weighted kappa = 0.79; 95% CI 0.69, 0.89), and 63% (weighted kappa = 0.70; 95% CI 0.60, 0.81), respectively. The group using the alternative rating system coupled with central monitoring yielded the highest inter-rater agreement among the three groups in rating GOS (97%; weighted kappa = 0.95; 95% CI 0.89, 1.00), and GOSE (97%; weighted kappa = 0.97; 95% CI 0.91, 1.00). The alternate system is an improved GOSE rating method that reduces inter-rater variations and provides for the first time, source documentation and structured narratives that allow a thorough central review of information. The data suggest that a collective effort can be made to minimize inter-rater variation.

Frontal cerebral vulnerability and executive deficits from raised intracranial pressure in child traumatic brain injury

In severe pediatric traumatic brain injury (TBI), a common focus of treatment is raised intracranial pressure (ICP). The aim of this investigation was to test whether raised ICP is associated with later prefrontal executive deficits and regional brain tissue loss, consistent with an anterior vascular compartment syndrome. Thirty-three participants were assigned to one of two severe TBI groups based on whether or not they had increased ICP complicating their critical illness. At follow-up (average 3.9 years), the participants underwent magnetic resonance imaging and a battery of neuropsychological testing focused on prefrontal function. The ICP group had white matter loss that was diffuse as well as regional in the corpus callosum, periventricular tissue, and frontal region. Loss of gray matter in the ICP group was more regionally specific, with bilateral loss in the caudate nuclei and frontal regions, including the right dorsolateral region, right supplementary motor area, and the left orbitofrontal cortex. Both groups had normal intelligence quotients (IQs), but the ICP group showed long-term deficits on various measures of attention and executive function such as working memory, decision-making, and impulsivity. These findings suggest that raised ICP leads to diffuse brain injury and a predilection to hypoperfusion in, at least, the distribution of the anterior cerebral artery. Furthermore, since voxel-based morphometry (VBM) and measures of attention and executive function are sensitive to the phenomenon of raised ICP, we consider that these techniques warrant inclusion in trials assessing ICP-directed therapy.

IMPACT recommendations for improving the design and analysis of clinical trials in moderate to severe traumatic brain injury

Clinical trials in traumatic brain injury (TBI) pose complex methodological challenges, largely related to the heterogeneity of the population. The International Mission on Prognosis and Clinical Trial Design in TBI study group has explored approaches for dealing with this heterogeneity with the aim to optimize clinical trials in TBI. Extensive prognostic analyses and simulation studies were conducted on individual patient data from eight trials and three observational studies. Here, we integrate the results of these studies into the International Mission on Prognosis and Clinical Trial Design in TBI recommendations for design and analysis of trials in TBI: Details of the major baseline prognostic characteristics should be provided in every report on a TBI study; in trials they should be differentiated per treatment group. We also advocate the reporting of the baseline prognostic risk as determined by validated prognostic models. Inclusion criteria should be as broad as is compatible with the current understanding of the mechanisms of action of the intervention being evaluated. This will maximize recruitment rates and enhance the generalizability of the results. The statistical analysis should incorporate prespecified covariate adjustment to mitigate the effects of the heterogeneity. The statistical analysis should use an ordinal approach, based on either sliding dichotomy or proportional odds methodology. Broad inclusion criteria, prespecified covariate adjustment, and an ordinal analysis will promote an efficient trial, yielding gains in statistical efficiency of more than 40%. This corresponds to being able to detect a 7% treatment effect with the same number of patients needed to demonstrate a 10% difference with an unadjusted analysis based on the dichotomized Glasgow outcome scale.