Closure intracranial pressure as a determinant of surgical decompression adequacy in spontaneous supratentorial intracerebral haematoma: a multicentre observational study.

PURPOSE: Despite significant advances, the literature on the optimal surgical treatment for spontaneous supratentorial intracerebral haematoma (ICH) remains lacking. Intraoperative ICP measured on closure (closure ICP) was reported to be a potential marker of adequate decompression in various neurosurgical conditions. We hypothesize that closure ICP also correlates with outcomes in ICH. METHODS: A multicentre retrospective study of 203 decompressive surgeries performed for ICHs was conducted (clot evacuation with either craniectomy or craniotomy). Receiver operating characteristic analysis on closure ICP was performed and an optimal threshold of 5 separated the patients into inadequate (iICP; ICP > 5 mmHg) and good decompression (gICP; ICP ≤ 5 mmHg). Postoperative ICP control, modified Rankin scale (mRS) and mortality were reported. RESULTS: There were 85 patients in the iICP and 118 patients in the gICP group respectively. The mean age, median preoperative Glasgow coma scale, ICH laterality, location, and volume were similar. After multivariable analysis, the need for (OR 2.55 [1.31-4.97]) and the duration of postoperative hyperosmolar therapy (iICP: 3 days, gICP: 1 day; p = 0.045), and repeat surgery for refractory ICP (OR 5.80 [1.53-22]) were more likely in the iICP group. The likelihood of mRS improvement at 1-year follow up was significantly worse in the iICP group (OR 0.38 [0.17-0.83], p = 0.015). CONCLUSION: Closure ICP is an objective and reproducible surgical target. When planning for surgical decompression, obtaining closure ICP of ≤ 5 mmHg is potentially able to improve postoperative ICP management and optimise functional recovery in a well selected patient population.

Outcomes of decompressive craniectomy for large territory cerebral infarction with and without prior reperfusion: a multicentre retrospective review.

PURPOSE: Reperfusion therapy has greatly improved outcomes of ischaemic stroke but remains associated with haemorrhagic conversion and early deterioration in a significant proportion of patients. Outcomes in terms of function and mortality are mixed and the evidence for decompressive craniectomies (DC) in this context remains sparse. We aim to investigate the clinical efficacy of DC in this group of patients compared to those without prior reperfusion therapy. METHODS: A multicentre retrospective study was conducted between 2005 and 2020, and all patients with DC for large territory infarctions were included. Outcomes in terms of inpatient and long-term modified Rankin scale (mRS) and mortality were assessed at various time points and compared using both univariable and multivariable analyses. Favourable mRS was defined as 0-3. RESULTS: There were 152 patients included in the final analysis. The cohort had a mean age of 57.5 years and median Charlson comorbidity index of 2. The proportion of preoperative anisocoria was 15.1%, median preoperative Glasgow coma scale was 9, the ratio of left-sided stroke was 40.1%, and ICA infarction was 42.8%. There were 79 patients with prior reperfusion and 73 patients without. After multivariable analysis, the proportion of favourable 6-month mRS (reperfusion, 8.2%; no reperfusion, 5.4%) and 1-year mortality (reperfusion, 26.7%; no reperfusion, 27.3%) were similar in both groups. Subgroup analysis of thrombolysis and/or thrombectomy against no reperfusion was also unremarkable. CONCLUSION: Reperfusion therapy prior to DC performed for large territory cerebral infarctions does not affect the functional outcome and mortality in a well-selected patient population.

Relevance of presenting risks of frailty, sarcopaenia and osteopaenia to outcomes from aneurysmal subarachnoid haemorrhage.

INTRODUCTION: Aneurysmal subarachnoid haemorrhage (aSAH) is a condition with significant morbidity and mortality. Traditional markers of aSAH have established their utility in the prediction of aSAH outcomes while frailty markers have been validated in other surgical specialties. We aimed to compare the predictive value of frailty indices and markers of sarcopaenia and osteopaenia, against the traditional markers for aSAH outcomes. METHODS: An observational study in a tertiary neurosurgical unit on 51 consecutive patients with ruptured aSAH was performed. The best performing marker in predicting the modified Rankin scale (mRS) on discharge was selected and an appropriate threshold for the definition of frail and non-frail was derived. We compared various frailty indices (modified frailty index 11, and 5, and the National Surgical Quality Improvement Program score [NSQIP]) and markers of sarcopaenia and osteopaenia (temporalis [TMT] and zygoma thickness), against traditional markers (age, World Federation of Neurological Surgery and modified Fisher scale [MFS]) for aSAH outcomes. Univariable and multivariable analysis was then performed for various inpatient and long-term outcomes. RESULTS: TMT was the best performing marker in our cohort with an AUC of 0.82, Somers' D statistic of 0.63 and Tau statistic 0.25. Of the frailty scores, the NSQIP performed the best (AUC 0.69), at levels comparable to traditional markers of aSAH, such as MFS (AUC 0.68). The threshold of 5.5 mm in TMT thickness was found to have a specificity of 0.93, sensitivity of 0.51, positive predictive value of 0.95 and negative predictive value of 0.42. After multivariate analysis, patients with TMT ≥ 5.5 mm (defined as non-frail), were less likely to experience delayed cerebral ischaemia (OR 0.11 [0.01 - 0.93], p = 0.042), any complications (OR 0.20 [0.06 - 0.069], p = 0.011), and had a larger proportion of favourable mRS on discharge (95.0% vs. 58.1%, p = 0.024) and at 3-months (95.0% vs. 64.5%, p = 0.048). However, the gap between unfavourable and favourable mRS was insignificant at the comparison of 1-year outcomes. CONCLUSION: TMT, as a marker of sarcopaenia, correlated well with the presenting status, and outcomes of aSAH. Frailty, as defined by NSQIP, performed at levels equivalent to aSAH scores of clinical relevance, suggesting that, in patients presenting with acute brain injury, both non-neurological and neurological factors were complementary in the determination of eventual clinical outcomes. Further validation of these markers, in addition to exploration of other relevant frailty indices, may help to better prognosticate aSAH outcomes and allow for a precision medicine approach to decision making and optimization of best outcomes.

The evolution of intracranial aneurysm treatment techniques and future directions.

Treatment techniques and management guidelines for intracranial aneurysms (IAs) have been continually developing and this rapid development has altered treatment decision-making for clinicians. IAs are treated in one of two ways: surgical treatments such as microsurgical clipping with or without bypass techniques, and endovascular methods such as coiling, balloon- or stent-assisted coiling, or intravascular flow diversion and intrasaccular flow disruption. In certain cases, a single approach may be inadequate in completely resolving the IA and successful treatment requires a combination of microsurgical and endovascular techniques, such as in complex aneurysms. The treatment option should be considered based on factors such as age; past medical history; comorbidities; patient preference; aneurysm characteristics such as location, morphology, and size; and finally the operator's experience. The purpose of this review is to provide practicing neurosurgeons with a summary of the techniques available, and to aid decision-making by highlighting ideal or less ideal cases for a given technique. Next, we illustrate the evolution of techniques to overcome the shortfalls of preceding techniques. At the outset, we emphasize that this decision-making process is dynamic and will be directed by current best scientific evidence, and future technological advances.

Closure intracranial pressure is an objective intraoperative determinant of the adequacy of surgical decompression in traumatic acute subdural haematoma: a multicentre observational study.

PURPOSE: Acute subdural haematoma (ASDH) is associated with severe traumatic brain injury and poor outcomes. Although guidelines exist for the decompression of ASDH, the question of adequate decompression remains unanswered. The authors examined the relationship of intracranial pressure (ICP) on closure with outcomes to determine its utility in the determination of adequate ASDH decompression. METHODS: A multicentre retrospective review of 105 consecutive patients with ASDH who underwent decompressive surgery was performed. Receiver operating characteristic (ROC) analysis with internal validation was performed to determine an ICP threshold for the division of patients into the inadequate and good ICP groups. Multivariable analyses were performed for both inpatient and long-term outcomes. RESULTS: An ICP threshold of 10 mmHg was identified with a 91.5% specificity, 45.7% sensitivity, and a positive and negative predictive value of 80.8% and 68.4%. There were 26 patients (24.8%) and 79 patients (75.2%) in the inadequate and good ICP groups, respectively. After adjustment, the inadequate ICP group was associated with increased postoperative usage of mannitol (OR 14.2, p < 0.001) and barbiturates (OR 150, p = 0.001). Inadequate ICP was also associated with increased inpatient mortality (OR 24.9, p < 0.001), and a lower rate of favourable MRS at 1 year (OR 0.08, p = 0.008). The complication rate was similar amongst the groups. CONCLUSIONS: Closure ICP is a novel, objective, and actionable intraoperative biomarker that correlates with inpatient and long-term outcomes in ASDH. Various surgical manoeuvres can be undertaken to achieve this target safely. Large-scale prospective studies should be performed to validate this ICP threshold.

External Validation of Hematoma Expansion Scores in Spontaneous Intracerebral Hemorrhage in an Asian Patient Cohort.

BACKGROUND: Hematoma expansion (HE) occurs in approximately one-third of patients with intracerebral hemorrhage (ICH) and is known to be a strong predictor of neurological deterioration as well as poor functional outcome. This study aims to externally validate three risk prediction models of HE (PREDICT, 9-point, and BRAIN scores) in an Asian population. METHODS: A prospective cohort of 123 spontaneous ICH patients admitted to a tertiary hospital (certified stroke center) in Singapore was recruited. Logistic recalibrations were performed to obtain updated calibration slopes and intercepts for all models. The discrimination (c-statistic), calibration (Hosmer-Lemeshow test, le Cessie-van Houwelingen-Copas-Hosmer test, Akaike information criterion), overall performance (Brier score, R2), and clinical usefulness (decision curve analysis) of the risk prediction models were examined. RESULTS: Overall, the recalibrated PREDICT performed best among the three models in our study cohort based on the novel matrix comprising of Akaike information criterion and c-statistic. The PREDICT model had the highest R2 (0.26) and lowest Brier score (0.14). Decision curve analyses showed that recalibrated PREDICT was more clinically useful than 9-point and BRAIN models over the greatest range of threshold probabilities. The two scores (PREDICT and 9-point) which incorporated computed tomography (CT) angiography spot sign outperformed the one without (BRAIN). CONCLUSIONS: To our knowledge, this is the first study to validate HE scores, namely PREDICT, 9-Point and BRAIN, in a multi-ethnic Asian ICH patient population. The PREDICT score was the best performing model in our study cohort, based on the performance metrics employed in this study. Our findings also showed support for CT angiography spot sign as a predictor of outcome after ICH. Although the models assessed are sufficient for risk stratification, the discrimination and calibration are at best moderate and could be improved.

Investigation of the usefulness of fluorescein sodium fluorescence in stereotactic brain biopsy.

BACKGROUND: Intraoperative frozen section assessment, to confirm acquisition of pathological tissues, is used in stereotactic brain biopsy to minimise sampling errors. Limitations include the dependence on dedicated neuro-oncology pathologists and an increase in operative duration. We investigated the use of intraoperative fluorescein sodium, and compared it to frozen section assessment, for confirming pathological tissue samples in the stereotactic biopsy of gadolinium-contrast-enhancing brain lesions. METHODS: This prospective observational study consisted of 18 consecutive patients (12 men; median age, 63 years) who underwent stereotactic biopsy of gadolinium-contrast-enhancing brain lesions with intravenous fluorescein sodium administration. Twenty-three specimens were obtained and examined for the presence of fluorescence using a microscope with fluorescence visualisation capability. Positive and negative predictive values were calculated based on the fluorescence status of the biopsy samples with its corresponding intraoperative frozen section and definitive histopathological diagnosis. RESULTS: Nineteen specimens (83%) were fluorescent and four (17%) were non-fluorescent. All 19 fluorescent specimens were confirmed to be lesional on intraoperative frozen section assessment and were suitable for histopathological diagnosis. Three of the non-fluorescent specimens were confirmed to be lesional on intraoperative frozen section assessment. One non-fluorescent specimen was non-diagnostic on frozen section and histological assessments. The positive predictive value was 100% and the negative predictive value was 25%. CONCLUSIONS: Fluorescein sodium fluorescence is as accurate as frozen section assessment in confirming sampling of pathological tissue in the stereotactic biopsy of gadolinium-contrast-enhancing brain lesions. Fluorescein sodium fluorescence-guided stereotactic biopsy is a useful addition to the neurosurgical armamentarium.

Intracranial Pressure as an Objective Biomarker of Decompression Adequacy in Large Territory Infarction: A Multicenter Observational Study.

Background: Decompressive craniectomy (DC) improves the survival and functional outcomes in patients with malignant cerebral infarction. Currently, there are no objective intraoperative markers that indicates adequate decompression. We hypothesise that closure intracranial pressure (ICP) correlates with postoperative outcomes. Methods: This is a multicentre retrospective review of all 75 DCs performed for malignant cerebral infarction. The patients were divided into inadequate ICP (iICP) and good ICP (gICP) groups based on a suitable ICP threshold determined with tiered receiver operating characteristic and association analysis. Multivariable logistic regression was performed for various postoperative outcomes. Results: An ICP threshold of 7 mmHg was determined, with 36 patients (48.0%) and 39 patients (52.0%) in the iICP and gICP group, respectively. After adjustment, postoperative osmotherapy usage was more likely in the iICP group (OR 6.32, p = 0.003), and when given, was given for a longer median duration (iICP, 4 days; gICP, 1 day, p = 0.003). There was no difference in complications amongst both groups. When an ICP threshold of 11 mmHg was applied, there was significant difference in the duration on ventilator (ICP ≥11 mmHg, 3-9 days, ICP <11 mmHg, 3-5 days, p = 0.023). Conclusion: Surgical decompression works complementarily with postoperative medical therapy to manage progressive cerebral edema in malignant cerebral infarctions. This is a retrospective study which showed that closure ICP, a novel objective intraoperative biomarker, is able to guide the adequacy of DC in this condition. Various surgical manoeuvres can be performed to ensure that this surgical aim is accomplished.

Microcatheter-Assisted Protection of the Posterior Inferior Cerebellar Artery During Parent Artery Sacrifice of a Vertebral Artery Dissecting Aneurysm.

Branch vessel occlusion is a major cause of stroke in parent artery sacrifice (PAS) for vertebral artery dissecting aneurysms (VADA). There is now an increasing trend towards preservation of branch vessels during PAS. Stents are commonly employed to achieve this but bring with it the attendant risks of future thrombosis and lifelong antiplatelet use. Although a microcatheter protection technique has been utilised in branch artery protection of wide-necked saccular aneurysms, it has rarely been described in PAS for VADAs. We describe the use of a dual microcatheter technique in the protection and remodelling of the posterior inferior cerebellar artery (PICA) during PAS of the vertebral artery, which also served as a temporary scaffold to support placement of the coils during the embolisation process.

The National Neuroscience Institute External Ventricular Drain Study: A Pragmatic Multisite Risk-Stratification Pathway to Reduce Ventriculostomy-Related Infection.

OBJECTIVE: Ventriculostomy-related infection (VRI) is associated with potential serious morbidity, extended hospitalization duration, increased health care costs, and mortality. We assessed the effectiveness of a pragmatic risk-stratification pathway for external ventricular drain (EVD) management, allowing for surgical decision making, in reducing the rate of VRIs. METHODS: Two studies were performed concurrently. A retrospective audit of EVD infection rates and outcomes in our unit across 3 hospitals was conducted from January to December 2014. The second prospective study compared the same variables during the implementation of the EVD pathway across the 3 sites from January 2015 to December 2016. RESULTS: The number of patients requiring EVDs increased from 2014 to 2016 (165 vs. 189 vs. 197 patients, respectively), with a significant increase in patients with intraventricular hemorrhage (P = 0.009). Despite increasing risk, overall EVD infections decreased during the implementation period, from 4.8% (8/165) in 2014 to 3.7% in 2015 (7/189) and 2.0% in 2016 (4/197, P = 0.33). In 2 sites (site 1, 2.0% vs. 2.1% vs. 1.9%, and site 2, 4.7% vs. 5.0% vs. 5.3%), transition to the EVD risk-stratification pathway maintained already low infection rates; in site 3, EVD infections decreased from 6.8% (5/73) to 3.9% (4/102) and 0% (0/86, P = 0.06). CONCLUSIONS: The introduction of a pragmatic evidence-based risk-stratification pathway, in which different options for EVD management are incorporated, results in low EVD infection rates across a multisite institutional practice. Our results are comparable to published protocols involving the implementation of standard care bundles and/or antibacterial EVDs alone, in reducing VRIs.

Adherence to guidelines for the referral of patients with colorectal cancer and abnormal tumour tissue testing for assessment of Lynch syndrome.

BACKGROUND: To determine the proportion of patients with colorectal cancer and abnormal immunohistochemistry testing of tumour tissue who were referred to a cancer genetic clinic for genetic counselling and possible germline testing of a blood sample for Lynch syndrome. METHODS: This is a retrospective cohort study of patients with colorectal cancer and abnormal immunohistochemistry tumour tissue testing from St Vincent's Hospital (between November 2007 and December 2016). Patient list was compared against a state-wide database TrakGene to ascertain the overall referral rate for these patients. RESULTS: Of 216 patients, the total referral rate was 33.8% (n = 73), of which 27.8% (n = 60) were referred to St Vincent's Hospital's Cancer Genetics Service, 6% (n = 13) were referred externally and the remaining 66.2% (n = 143) were not referred. Binomial regression analysis performed displayed that age influenced likelihood of referral, where patients were 7.7% more likely to be referred for every decreasing year in age (P = 0.0004). Some clinicians were 4.3 times more likely to refer patients compared to others (P = 0.002). CONCLUSION: Suboptimal patient uptake for cancer genetics evaluation was found. Identifying barriers to patient referral should lead to changes that increase patient referrals. This will ensure that patients receive adequate education, counselling and management of Lynch syndrome. It would also allow for the identification of further at-risk relatives for whom preventative strategies can be employed. In addition, identification of relatives not at risk by genetic testing will liberate them from unnecessary colonoscopies. Discussion with the clinicians involved has since allowed for copies of the immunohistochemistry results to be forwarded by the Pathology Department to the Cancer Genetics Unit for checking and follow up with the clinician to ensure that their patients are aware of the result and have been offered referral for cancer genetic evaluation. This process is subject to ongoing audit.

Effects of anticoagulant and antiplatelet agents in severe traumatic brain injury in an asian population - A matched case-control study.

The use of anticoagulation and antiplatelet agents (ACAP) has steadily increased over recent years. However, the effects of ACAP on traumatic brain injuries (TBI) are not well investigated. The aim of this study was to investigate the effects of pre-injury ACAP use on clinical outcome and mortality in severe TBI. A retrospective case-control study was performed for all patients who presented with severe TBI (GCS < 8) to the National Neuroscience Institute, Singapore, between 2006 and 2009. Patients with pre-injury ACAP use were compared to matched controls. Outcome measures were mortality at 14 days and 6 months, and Glasgow Outcome Score (GOS) at 6 months using a sliding dichotomy approach. Univariate analysis was performed using Chi-square and student's t-test and logistic regression was used to model the effect of ACAP on mortality rate. Forty-five patients with pre-injury use of ACAP were compared with matched controls. The mortality at 14 days (OR = 0.5, 95% CI 0.2-1.4) and 6 months (OR = 0.7, 95% CI 0.2-1.9) were not significantly different between the 2 groups. Using the sliding dichotomy approach, there was no difference in the odds for unfavorable functional outcomes at 6 months (OR = 1.2, 95% CI 0.4-3.7). In this case-control study, the use of ACAP did not have a significant effect on mortality and adverse outcomes in patients with severe TBI. This would suggest that in severe TBI, ACAP use may not contribute significantly to the overall prognosis.

Surgical resection of carotid-jugular arteriovenous fistula after multiple failed embolisation.

Carotid-jugular fistula is a rare presentation of arteriovenous fistula. A case of a 60-year-old Chinese man who presented with iatrogenic carotid-jugular fistula with multiple fistulous points was reported. His presenting complaint was a gradually enlarging right pulsatile neck mass complicated by worsening symptoms of congestive cardiac failure. He had recent mitral valve annuloplasty, and a right internal jugular central venous pressure monitor insertion was performed then. Angiography revealed right carotid-jugular fistula with feeders from the external carotid, internal carotid and right vertebral arteries, all draining into the right internal jugular vein. He underwent embolisation twice resulting in transient improvement in clinical symptoms, and surgical resection was later performed in view of residual arteriovenous shunting and gradual clinical deterioration. Following surgery, he was discharged and resumed work as a janitor with no recurrent symptoms for 3 years now. In this report to be added into the literature, we discuss a rare case of iatrogenic carotid-jugular fistula with multiple fistulous points which required embolisation and subsequently surgical resection.

Validation of Prognostic Models to Predict Early Mortality in Spontaneous Intracerebral Hemorrhage: A Cross-Sectional Evaluation of a Singapore Stroke Database.

OBJECTIVE: Numerous scores have been developed for prognostication of outcomes in intracerebral hemorrhage (ICH). Prediction models must be validated internally and externally before they are considered widely applicable. We aim to independently externally validate and compare 3 prediction models (ICH score, ICH grading scale [ICH-GS], and simplified ICH [sICH]) in our population, which has not been previously done. METHODS: We reviewed 1338 patients with spontaneous ICH consecutively admitted to the National Neuroscience Institute, Singapore, between January 2009 and November 2013. We analyzed prospectively collected data of admission characteristics (clinical, neuroimaging, and laboratory findings). All 3 scores prognosticated 30-day mortality. Validation was based on calibration, goodness-of-fit tests, and discrimination (area under receiver operating characteristic curve [AUC]). Akaike information criterion (AIC) and decision curve analysis (DCA) were used to directly compare the scores. RESULTS: All 3 models showed good calibration and both the Hosmer-Lemeshow and the le Cessie-van Houwelingen-Copas goodness-of-fit test showed P values >0.05. AUCs ranged from 0.86 to 0.90, indicating good discriminative ability, with the ICH-GS performing the best with the highest AUC, lowest AIC (849), and overall highest net benefit in the DCA. CONCLUSIONS: This study successfully independently validates the ICH score, ICH-GS, and sICH score in a large patient cohort with spontaneous ICH, which has not been previously done in this non-Western population. We recommend the use of the ICH-GS as a prognostication tool in our patients instead of the widely used ICH score.

A meta-analysis comparing ALIF, PLIF, TLIF and LLIF.

INTRODUCTION: Lumbar interbody fusions have been widely used to treat degenerative lumbar disease that fails to respond to conservative treatment. This procedure is divided according to its approach: anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), transforaminal lumbar interbody fusion (TLIF) and lateral lumbar interbody fusion (LLIF). Each approach has its own theoretical advantages and disadvantages; however, there have been no studies that compared these. METHODS: Various full-text databases were systematically searched through December 2015. Data regarding the radiological, operative and clinical outcomes of each lumbar interbody fusion were extracted. All outcomes were pooled using random effects meta-analysis, with the relative risk (RR) and/or weighted mean difference (WMD) as the summary statistic. RESULTS: Thirty studies met the inclusion criteria. The ALIF procedure has been studied most intensively, followed by PLIF, TLIF and LLIF respectively. All four approaches had similar fusion rates (p=0.320 & 0.703). ALIF has superior radiological outcome, achieving better postoperative disc height (p=0.002 & 0.005) and postoperative segmental lordosis (p=0.013 & 0.000). TLIF had better Oswestry Disability Index scores (p=0.025 & 0.000) while PLIF had the greatest blood loss (p=0.032 & 0.006). Complication rates were similar between approaches. Other comparisons were either inconclusive or lacked data. There was marked less studies comparing against LLIF. CONCLUSIONS: Each approach has their own risks and benefits but similar fusion rates. Despite the large number of studies, there is little data overall when comparing specific aspects of lumbar interbody fusions. More studies, especially RCTs are needed to further explore this topic.

Models of Mortality and Morbidity in Severe Traumatic Brain Injury: An Analysis of a Singapore Neurotrauma Database.

OBJECTIVE: Current prognostic models for traumatic brain injury (TBI) are developed from diverse historical data sets. We aimed to construct a prognostication tool for patients with severe TBI, as this group would benefit most from an accurate model. METHODS: Model development was based on a cohort of 300 patients with severe TBI (Glasgow Coma Scale score ≤8) consecutively admitted to a neurosurgical intensive care unit at the National Neuroscience Institute (NNI), Singapore, between February 2006 and December 2009. We analyzed prospectively collected data of admission characteristics using univariate and multivariate logistic regressions to predict 14-day and 6-month mortality and 6-month unfavorable outcome. Comparison with Corticosteroid Randomization After Significant Head Injury (CRASH) and Mission for Prognosis and Analysis of Clinical Trials in TBI (IMPACT) models was done using Akaike information criterion. RESULTS: Two prediction models, NNI Clinical (age, Glasgow Coma Scale score, pupillary reactivity) and NNI+ (NNI Clinical model with addition of obliteration of third ventricle or basal cisterns, presence of subdural hemorrhage, hypoxia, and coagulopathy), were derived from this data set. Both models predicted well across 3 outcome measures with area under the curve values of 0.84-0.91, with adequate calibration. Comparison with CRASH and IMPACT models showed better performance by both derived models with lower Akaike information criterion and higher area under the curve values. CONCLUSIONS: Two accurate prognostic models, NNI Clinical and NNI+, were developed from our cohort of patients with severe TBI. Both models are specific to severe TBI and could be better alternatives to current available models. External validation is required to assess performance of models in a different setting.

External validation of the CRASH and IMPACT prognostic models in severe traumatic brain injury.

An accurate prognostic model is extremely important in severe traumatic brain injury (TBI) for both patient management and research. Clinical prediction models must be validated both internally and externally before they are considered widely applicable. Our aim is to independently externally validate two prediction models, one developed by the Corticosteroid Randomization After Significant Head injury (CRASH) trial investigators, and the other from the International Mission for Prognosis and Analysis of Clinical Trials in Traumatic Brain Injury (IMPACT) group. We used a cohort of 300 patients with severe TBI (Glasgow Coma Score [GCS] ≤8) consecutively admitted to the National Neuroscience Institute (NNI), Singapore, between February 2006 and December 2009. The CRASH models (base and CT) predict 14 day mortality and 6 month unfavorable outcome. The IMPACT models (core, extended, and laboratory) estimate 6 month mortality and unfavorable outcome. Validation was based on measures of discrimination and calibration. Discrimination was assessed using the area under the receiving operating characteristic curve (AUC), and calibration was assessed using the Hosmer-Lemeshow (H-L) goodness-of-fit test and Cox calibration regression analysis. In the NNI database, the overall observed 14 day mortality was 47.7%, and the observed 6 month unfavorable outcome was 71.0%. The CRASH base model and all three IMPACT models gave an underestimate of the observed values in our cohort when used to predict outcome. Using the CRASH CT model, the predicted 14 day mortality of 46.6% approximated the observed outcome, whereas the predicted 6 month unfavorable outcome was an overestimate at 74.8%. Overall, both the CRASH and IMPACT models showed good discrimination, with AUCs ranging from 0.80 to 0.89, and good overall calibration. We conclude that both the CRASH and IMPACT models satisfactorily predicted outcome in our patients with severe TBI.