Title: Guidelines for The Management of Traumatic Brain Injury: An Impact Assessment and Further Development.
Funder: Department of Health and Social Care

Abstract: Background: Every year there are 1.4 million attendances to Emergency Departments in England and Wales following a head injury. A small number of these patients have significant brain injuries and are at risk of death without neurosurgical intervention. NICE guidelines were introduced in 2003 to improve outcomes following head trauma. They recommended increased use of computed tomography (CT) head imaging to detect significant brain injuries and the management of patients with severe injuries in specialist centres. The guidelines were expected to reduce deaths and hospital admissions. The impact of the NICE head injury guidelines on mortality and admissions has not been rigorously assessed. Almost all mild traumatic brain injury patients who have minor CT head scan abnormalities are admitted to hospital due to the risk of deterioration. However, only 15% of admitted patients deteriorate. Better understanding of the factors influencing patients' risk of deterioration will allow hospital admissions to be better targeted. Aim: This research will assess the impact of the NICE guidelines and how they can be refined to reduce unnecessary hospital admissions. Objectives: 1) Assess the impact of the introduction of the NICE guidelines on deaths from traumatic brain injury. 2) Assess the impact of the introduction of the NICE guidelines on the number and rate of hospital admissions due to head injury. 3) Assess whether any increase in admissions are due to the identification of more traumatic brain injuries that do not require neurosurgery. 4) Develop a prognostic model that risk stratifies mild traumatic brain injury patients who have minor CT head scan abnormalities and estimate the extent to which hospital admissions could potentially be reduced by its use. Plan of investigation: Hospital episode statistic data linked to Office of National Statistics mortality data will be used to identify hospital admissions and deaths due to head injury from 1998 to 2016. An interrupted time series analysis will be conducted to assess the impact of the introduction of NICE head injury guidelines in 2003 (revised in 2007 and 2014) on level and trends in traumatic brain injury deaths and hospital admissions due to head injury. Analysis of a subset of traumatic brain injury patients with diagnostic codes related to abnormalities detected by CT head imaging will be completed. The impact of the introduction of the NICE guidelines on the level and trends of hospital admissions and neurosurgery in this group will be assessed using an interrupted time series analysis. To develop a clinical risk model, I will first conduct a systematic review, using international standards, to identify patient and radiological factors associated with poor outcomes in mild traumatic brain injury patients that have minor CT head scan abnormalities. I will then estimate how well these factors predict deterioration in a retrospective cohort of patients. Logistic regression will be used to estimate a prognostic model. The predictive accuracy of this will be assessed by applying it to another retrospective cohort of patients. The risk model will be used to develop a clinical-risk tool to inform discharge decisions. I will estimate the potential impact on admissions of using this model Benefit to patients and the NHS: Implementing the NICE head injury guidelines represented a large expenditure of NHS resources. It is important to assess whether these guidelines have been effective, and potentially caused an increase in unnecessary hospital admissions. Developing a clinical risk assessment tool for mild traumatic brain injury patients that have minor CT head scan abnormalities will help refine the NICE head injury guidelines to allow better risk stratification of this group. Better risk stratification would inform shared decision-making and could reduce the rate and length of admissions.

Lay abstract: Background: There are 1.4 million Emergency Department attendances for head injury in England and Wales a year. Most of these patients have minor head trauma and are at low risk of serious brain injury. NICE head injury guidelines were introduced in 2003. They indicate which patients require CT head imaging and how patients with serious brain injuries should be treated. The aim was to reduce head trauma deaths through increased CT head imaging and better management of patients with severe injuries. Whether this has been achieved has not been rigorously assessed. The NICE head injury guidelines were predicted to be cost effective, with the increased cost of CT head imaging being offset by fewer hospital admissions. However, there is some evidence suggesting that head injury admissions have increased since the guidelines were introduced. The impact of the guidelines on admission rates needs more research. Minor head injury patients who undergo CT head imaging and have brain injuries identified are admitted to hospital in case they deteriorate. However, only a small proportion of those admitted do deteriorate. Research is needed to help identify the factors that predict deterioration in admitted patients. This may help to reduce the number and length of hospital admissions by better identifying patients who are at low risk of deterioration. Aim: This research will assess the impact of the NICE guidelines and how they can be refined to reduce unnecessary hospital admissions. Objectives: 1) Assess the impact of the introduction of the NICE guidelines on deaths from traumatic brain injury. 2) Assess the impact of the introduction of the NICE guidelines on the number and rate of hospital admissions due to head injury. 3) Assess whether any increase in admissions are due to the identification of more traumatic brain injuries that do not require neurosurgery. 4) Develop a prognostic model that risk stratifies mild traumatic brain injury patients who have minor CT head scan abnormalities and estimate the extent to which hospital admissions potentially could be reduced by its use. Method: The first part of this project (objectives 1,2 and 3) will use routinely collected hospital episode statistics (HES), containing details of diagnoses and admissions at NHS hospitals in England linked to national mortality data. Data will be analysed from 1998 to 2016 for those admitted to hospital before and after the guideline was introduced. I will use a technique called an Interrupted Time Series Analysis to assess the impact the NICE guidelines on deaths and hospital admissions. Using this approach I will analyse if there were changes in the number and trend of associated deaths and admissions. For objective 4, I will conduct a systematic review to identify factors that might affect deterioration in patients with mild traumatic brain injuries who have minor CT head scan abnormalities. I will then extract information from a review of the case notes of 2500 hospital patients to assess the extent to which these factors predict deterioration in this patient group. This statistical model will form the basis of a clinical tool that uses patient information and radiological findings to risk assess patients and help decide whether, and how long they should be admitted to hospital. I will then test how well this tool performs by applying it to data from a separate group of patients. Patient and public involvement The Headway charity and a hospital-based patient public involvement group were engaged in the preparatory phase of this research. Assessing whether the NICE guidelines represent effective and efficient care is high priority for all patient groups. Patients with potential minor head injuries felt that identifying individual risk would facilitate joint decision-making regarding hospital admission. As this project involves analysis of retrospective and routinely collected data there is limited scope for patient involvement in the execution phase. However, we have agreed that I will discuss the findings of the research with both patient groups to assess which findings are important to different stakeholders and how the research could be developed. The hospital-based patient public group will assess the protocol for the retrospective data collection and help develop a protocol for prospective data collection for the validation of the decision-tool. Dissemination The Headway charity will disseminate relevant findings to stakeholder groups. This research will be communicated to health professionals and research community through publication in peer reviewed journals and presentation at research conferences. I will engage with bodies including NICE and the Royal College of Emergency Medicine, to influence their guidelines.

Research activity codes: 4.1 DISCOVERY AND PRECLINICAL TESTING OF MARKERS AND TECHNOLOGIES;7.3 MANAGEMENT AND DECISION MAKING
Health categories: INJURIES AND ACCIDENTS