NHS Digital Data Release Register - reformatted
Hull And York Medical School projects
3 data files in total were disseminated unsafely (information about files used safely is missing for TRE/"system access" projects).
An Impact Assessment of National Head Injury Guidelines Using an Interrupted Time Series — DARS-NIC-61042-K9Q3G
Type of data: information not disclosed for TRE projects
Opt outs honoured: N, Anonymised - ICO Code Compliant (Does not include the flow of confidential data)
Legal basis: Health and Social Care Act 2012, Section 42(4) of the Statistics and Registration Service Act (2007) as amended by section 287 of the Health and Social Care Act (2012), Health and Social Care Act 2012 s261(1) and s261(2)(b)(ii), Health and Social Care Act 2012 s261(2)(b)(ii)
Purposes: No (Academic)
Sensitive: Non Sensitive, and Sensitive, and Non-Sensitive
When:DSA runs 2019-03-10 — 2020-03-09 2018.03 — 2018.05.
Access method: One-Off, Ongoing
Data-controller type: UNIVERSITY OF HULL
Sublicensing allowed: No
Datasets:
- Hospital Episode Statistics Admitted Patient Care
- Office for National Statistics Mortality Data
- Bridge file: Hospital Episode Statistics to Mortality Data from the Office of National Statistics
- Civil Registration (Deaths) - Secondary Care Cut
- HES:Civil Registration (Deaths) bridge
- Civil Registrations of Death - Secondary Care Cut
- Hospital Episode Statistics Admitted Patient Care (HES APC)
Objectives:
Nature of Project:
This is a National Institute for Health Research funded PhD fellowship that will use hospital episode statistic data to assess the impact of the introduction of national head injury (NICE) guidelines on deaths from traumatic brain injury and hospital admissions for head injury. This forms part of a larger project that aims to evaluate and refine the current national clinical (NICE) guidelines used for the emergency management of head injured patients in the United Kingdom.
Background:
Head injury is very common. There are 1.4 million emergency department attendances annually in England and Wales following a head injury. The majority of these patients can be safely reassured and sent home. A small number of patients have life-threatening brain injuries that need to be immediately identified and treated. The difference between the two groups is not always initially clinically apparent.
National clinical (NICE) guidelines for the management of head injured patients were introduced in 2003, 2007 and 2014 in England and Wales. They recommended increased CT brain imaging of head injured patients and that patients with severe brain injuries should be managed in specialist centres. This aimed to ensure all patients with life-threatening injuries were identified and that patients with severe injuries had improved outcomes through specialist care. The increased costs of more imaging were planned to be offset by a reduction in hospital admissions of head-injured patients. It was thought that patients previously admitted for observation due to uncertainty about whether they had significant brain injuries would be discharged from the Emergency Department following normal CT imaging.
There has not previously been a comprehensive evaluation of the impact of the introduction of the NICE head injury guidelines. There is limited evidence that they have reduced deaths from traumatic brain injury. Hospital admissions for head injury have increased by over 50% since the introduction of the head injury guidelines. It has been hypothesised this may be due to increased CT imaging leading to the identification of small brain injuries of debatable clinical significance that would previously not have been identified. It important to assess whether the NICE head injury guidelines are clinically effective and whether their introduction has contributed to more hospital admissions and therefore increased costs for the NHS.
Aim:
This research will robustly assess the impact of the NICE head injury guidelines.
Objectives:
1) Assess the impact of the introduction of each iteration of the NICE guidelines on deaths from traumatic brain injury.
2) Assess the impact of the introduction of each iteration of the NICE guidelines on the number and rate of hospital admissions due to head injury.
3) Assess the size of any increase in hospital admissions for head injury due to the unintended identification of more traumatic brain injuries of lower clinical significance due to increased CT imaging.
Yielded Benefits:
Statistical analysis of the mortality linked HES data extract has provided evidence that the only NICE Head Injury guideline associated with a reduction in the mortality rate from traumatic brain injuries was the guideline iteration that recommended patients with severe injuries are managed in specialist centres. The effect was limited to the 16-65 age group. In patients over 65, the mortality rate from traumatic brain injury increased and was unaffected by the introduction of any guideline. This provides evidence to the NHS that although NICE guidelines recommending increased CT imaging may reduce hospital admissions and costs for the NHS, improved traumatic brain injury outcomes requires diagnosis to be coupled with specialist care. The increasing mortality rate in older patients from traumatic brain injury requires further investigation. It may mean either older patients have unequal access to specialist care or that specialist care is less effective in this group. This has implications for future research and the provision of NHS services treating the increasing number of older patients with traumatic brain injuries.
Expected Benefits:
The benefits noted below have been taken directly from the applicants NIHR Funding Application and is therefore written in the first person.
The nature of the proposed research involves the analysis of retrospective routinely collected data. Therefore the scope for public patient involvement in the execution phase of this research is limited. However, I have agreed to continue engaging with both stakeholder groups consulted in the preparatory phase of this research to explore the importance of the research to them, help with interpretation and in developing this research further.
My proposed research will explore whether the NICE guidelines have reduced head injury mortality and at what cost to the NHS. I will summarise and discuss these findings with the Trans-Humber Consumer Research Panel and a Headway Charity patient group to assess whether they feel that the NICE head injury guidelines represent effective care and good value for the NHS. Using these findings we will discuss how the NICE guidelines could be improved and what further research would be a priority.
In particular, the Trans-Humber research panel chairman and individual members were keen to be involved further in developing the decision rule aspect of the proposed research. I intend to form a long-term relationship with this group. I will return to them with a draft final protocol for this aspect of research for them to consider from a patient perspective. I will also share with them a draft risk-model for patients with abnormal CT head imaging.
We will discuss how such a model could be applied in practice to facilitate shared decision making between patients and clinicians. We will assess what further research may be necessary in order to inform the implementation of such a model into clinical practice. The Hull Headway patient group has also agreed to act as a patient advisory group for the proposed research. They have agreed to meet with me once a year. We will discuss how my research is progressing and whether it
could be refined to better encompass their priorities. At the end of this fellowship I will consult with the Headway patient group in developing a protocol for post-doctoral research aimed at assessing longer-term health care needs for patients with head injury (see future plans).
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.
Outputs:
Aggregate level monthly data will be produced for: the non-adjusted and adjusted mortality rate of traumatic brain injury; emergency hospital admissions for head injury compared to emergency admissions for other conditions; proportion of patients with sociologically detected brain injuries that do not undergo neurosurgery. Aggregate data with small numbers suppressed in line with the HES analysis guide will be summarised in charts, tables and figures.
Aggregate level data with small number suppressed in line with the HES analysis guide will be: assessed by other researchers in the research team at meetings in Hull York Medical School.
Aggregate level data with small numbers suppressed in line with the HES analysis guide will be presented at relevant research conferences (this includes national Royal College of Emergency Medicine conferences, International Brain Injury Conferences and NIHR conferences of funded fellowships) ; disseminated in academic publications; and will form a final report for the National Institute of Health Research.
The projected timeline of specific formal outputs is detailed below, and data will be aggregated with small numbers suppressed in line with the HES analysis guidelines.
Study results will be compiled for academic publications and are projected to contribute to at least two peer-reviewed scientific articles published in relevant clinical journals such as the BMJ Emergency Medicine Journal and Journal of Neurotrauma by 2020.
Abstracts of study results will be submitted to 2 Annual Scientific Conferences in Emergency Medicine (September 2019, September 2020) and at the World Congress in Brain Injury 2018. Study results will also be submitted for presentation at NIHR conferences of funded research in 2019 and 2020.
An abstract of results of the study will also be submitted to the NICE annual conference in 2020 in order to help inform the development of a further iteration of national clinical head injury guidelines.
Results of the study will be disseminated directly in the form of a presentation to the local branch of the HEADWAY head injury charity by September 2019 and this group includes former brain injury patients, carers, and healthcare professionals. The results will be communicated to the HEADWAY charity at a national level in the form of a summary report to the charity’s Publication and Research Manager. The charity may choose to further disseminate the results of the research in national newsletters and on the charity’s website.
Results of the study will form a final report to the National Institute of Health Research in September 2019.
Processing:
The University of Hull is the data controller for this project the research contract for the NIHR Doctoral Fellowship for the lead investigator is between the University of Hull and Secretary of State for Health. However, no data will be: provided to; stored at; accessed in; or processed at; the University of Hull.
All data provided by NHS Digital will be stored, accessed and processed solely at the University of York Department of Health Sciences. This data will not be shared with any other parties and will be stored for the agreed duration of this project. The data set supplied will only be used for the purposes of this research project and not be used for any other purpose. All outputs will be at an aggregate level with small numbers suppressed in line with the HES analysis guidelines. Reccord level data will only be accessed by University of York researchers conducting analysis for this project. This includes: the lead investigator a Hull York Medical School NIHR Doctoral Research Fellow , a University of York Professor of Health Sciences and Hull York Medical School’s Senior Statistician.
Request Data:
An pseudonymised data set of record level data for all emergency admissions to hospital from 1998-2017 will be extracted by NHS Digital from the Inpatient Hospital Episode Statistic data set.
Linkage to mortality data is requested only for admission episodes with ICD 10 diagnostic codes related to head injury. These include S00-S09, T04.0 and T06.0.
HES data will be used to achieve the following objectives of the research project:
1) Assess the impact of the introduction of each iteration of the NICE guidelines on the number and rate of hospital admissions due to head injury.
2) Assess the size of any increase in hospital admissions for head injury due to the unintended identification of more traumatic brain injuries of lower clinical significance due to increased CT imaging.
In order to achieve the objectives with the minimum required HES data the Data Access Request Service technical team were involved in determining which data were required and the following measures have been taken:
1) Data fields have been selected to ensure the minimum required clinical data is provided for the planned analysis and duplicated forms of data are not requested.
2) Only the necessary pseudonymised HES specific episode information is requested to allow the planned analysis of changes in hospital admissions.
3) In total less than 50% of possible data fields are requested.
4) The focus of the project is the emergency management of head injury and therefore only data on emergency admissions is requested.
5) Data is requested for the period of 1998-2017 as the impact of 3 iterations of the NICE clinical guidelines is being assessed. These were introduced in 2003, 2007 and 2014 and therefore data from 1998-2017 is required in order to complete the planned analysis.
6) Data on all emergency admissions is requested for the period of 1998-2017. This is required to allow a comparison between trends in emergency admissions for head injured patients and patients with other conditions.
The objective of the part of the project that uses ONS mortality data is to assess whether the introduction of NICE clinical guidelines for head injury reduced deaths due to severe traumatic brain injury. The data requested is minimised in the following ways, whilst allowing this objective to be accomplished:
1) ONS mortality data is only requested for patients admitted to hospital with ICD 10 codes that relate to head injury (S00-S09, T04.0 and T06.0)
2) The period of the study is from April 1998 to December 2017, and so data is only requested for this period.
3) Patient identifiable data, including the date of death, is not requested as this is not required for the planned analysis.
4) Field selection has been minimised to that required to identify the cause of death and link patients to the HES inpatient data set.
Data Analysis:
1) Assess the impact of the introduction of each iteration of the NICE guidelines on deaths from traumatic brain injury.
Emergency admission episodes that are for traumatic brain injury will be identified by ICD 10 diagnostic coding (S00-S09, T04.0 and T06.0) for the period 1998-2017. These episodes will be linked to ONS mortality data for deaths as an inpatient and up to 30 days following discharge. Where a death has occurred data will be coded as either due to traumatic brain injury or due to another cause. Monthly aggregate totals of deaths due to traumatic brain injury for this population will be produced for this time period. These will be converted to a rate using estimates of the population of England. A monthly time series will be produced and segmented regression analysis will be used to assess whether national head injury guidelines introduced in 2003, 2007 and 2014 reduced deaths in this population. The analysis will be stratified into paediatric (aged under 16) and adult populations.
The monthly mortality rate will then be adjusted for age, sex, comorbidity and injury severity using multivariable logistic regression. Age at the beginning of each hospital admission episode for traumatic brain injury will be used. Gender recorded for the hospital admission episode for traumatic brain injury for each patient will be used and will be coded male, female or unknown when not recorded. Each ICD 10 head injury diagnostic code subtype will be coded separately and will be used to give an indication of the severity of injury. Co-morbidities will be grouped and coded based on subtype and significance. Regression analysis will be used to assess the impact of these factors on the likelihood of death for patients admitted with diagnostic codes relating to traumatic brain injury. An adjusted monthly mortality rate, taking into account these factors, will then be produced for deaths due to traumatic brain injury for the time period of interest. This will be used to create a monthly time series of adjusted mortality rates and segmented regression analysis will be used to assess the impact of the different iterations of the NICE head injury guidelines on deaths. This analysis of adjusted mortality will ensure that observed changes are not due to underlying changes in the population.
2) Assess the impact of the introduction of each iteration of the NICE guidelines on the number and rate of hospital admissions due to head injury.
Emergency hospital admission episodes for ICD10 codes related to head injury (ICD10 codes S00-S09, T04.0 and T06.0.) between 1998-2017 will be identified in the data extract of all emergency admissions for this time period of inpatient Hospital Episode Statistics. These will be aggregated on a monthly basis and converted into a rate of hospital admissions for head injury based on estimates of the population of England. A time series and segmented regression analysis will be used to assess for changes in the level and trend of admission rate after the introduction of each iteration of the head injury guidelines.
In order to ensure that increases are not due to underlying changes in the population analysis will be repeated with stratification by age grouping, significant comorbidity, gender and injury severity. Ages will be grouped into: 0-16; 16-30; 30-45; 45-65; 65-85; and 85+. The other variables will be separately coded for. Rates of admission for head injury will also be compared on a monthly basis for the time period of interest to the emergency admission rate for non-head injury trauma and medical emergency admissions. Analysis in these groups will be stratified in the same way into age grouping, comorbidity and gender. This will indicate whether there has been a disproportionate increase in head injury admissions attributable to the introduction of the NICE head injury guidelines or whether increases reflect general trends for increased hospital admissions due to other factors including the introduction of the 4-hour Emergency Department target that occurred contemporaneously to the introduction of the 2004 NICE head injury guideline.
3) Assess the size of any increase in hospital admissions for head injury due to the unintended identification of more traumatic brain injuries of lower clinical significance due to increased CT imaging.
ICD10 codes S02 and S06 will be used to identify emergency hospital admission episodes for patients with injuries that require CT imaging in the data extract of inpatient Hospital Episode Statistics of all emergency admissions between 1998-2017. OPSC-4 intervention codes for neurosurgical intervention (A05.2, A05.3, A05.4, A05.8, A05.9, A40.1, A40.8, A40.9, A41.1, A41.8, A41.9, V03.1, V03.2, V03.3, V03.4, V03.6, V03.7, V03.8, V03.9, V05.3 and V05.4) will be coded for to indicate a neurosurgical intervention has taken place. The proportion of these patients that do not undergo neurosurgery will be measured on a monthly basis. A monthly time series of the proportion of patients with injuries detected by CT imaging who do not undergo CT imaging will be plotted. Segmented regression analysis will be used to assess whether the introduction of the national head injury guidelines has led to an increase in admissions for patients that do not require neurosurgery.
An overall estimate of excess hospital admissions for patients that did not require neurosurgery will be estimated over the time-period from the introduction of the first NICE head injury guideline. This will give an indication of the total unexpected costs associated with the introduction of the guidelines and the potential impact a hospital admission risk tool for patients with small traumatic brain injuries being developing as part of this fellowship could have in reducing hospital admissions in this group.
A second parallel component of the NIHR doctoral fellowship involves the development of a risk stratification tool for the discharge of low-risk patients with traumatic brain injuries. This is separate to the analysis being completed with ONS linked data. However, the analysis being undertaken for objective 3 of the project using ONS linked HES data involves estimating the number of excess hospital admissions that resulted from increased CT imaging leading to the identification of injuries of uncertain clinical significance. The risk stratification tool being developed in parallel is aimed at identifying low-risk patients with brain injuries who could be safely discharged.
All organisations party to this agreement must comply with the Data Sharing Framework Contract requirements, including those regarding the use (and purposes of that use) by “Personnel” (as defined within the Data Sharing Framework Contract ie: employees, agents and contractors of the Data Recipient who may have access to that data).
ONS Terms and Conditions will be adhered to.