The AHEAD Study: monitoring anticoagulated patients who suffer head injury

Study contacts

Chief investigator: Professor Suzanne Mason
Email: s.mason@sheffield.ac.uk
Tel: 0114 222 0694

Study manager: Maxine Kuczawski
Email: m.kuczawski@sheffield.ac.uk
Tel: 0114 222 2981

Background

Existing practice in emergency departments (ED) in the UK for managing patients taking warfarin after a blunt head injury is variable with little research that supports the most appropriate way to manage these patients. We aimed to undertake research in order to understand the range and frequency of outcomes following head injury in this group of patients and to develop robust clinical guidance for how they should be optimally managed in the future.

The AHEAD Study was a prospective observational study which enrolled patients taking warfarin who attended 33 ED’s in England and Scotland after blunt head injury. Over an 18-month period from October 2011, ED attendance data was collected from each site as well as information from patient questionnaires about the care they received and the status of their health 6 weeks after the injury. Patients who died due to their head injury, experienced surgery due to their injury, had a change identified on a CT scan or re-attended the ED with a clear head injury complication were defined as experiencing a poor outcome. Information such as the patients’ conscious state (GCS), level of clotting in their blood (INR) and symptoms were investigated as predictors of a poor outcome. A mathematical model was used to estimate the most cost-effective strategy assuming published NICE thresholds for cost per quality adjusted life year (QALY).

Aims

  • Identify and determine incidence of clinically significant outcomes
  • Identify predictors of adverse outcomes
  • Identify cost-effectiveness of different models of care
  • Develop robust clinical guidance to reduce risk of complication and death

Results

A total of 3566 patients were enrolled in The AHEAD Study; the age range was 18 to 101 yrs (mean 79yrs) and 49% were men. Most patients were generally well on arrival in the ED and only 1/3 reported any symptoms (amnesia, vomiting, loss of consciousness or headache). The average level of clotting in the blood tended to fall in the ‘normal range’ (mean INR 2.7). Imaging of the head was performed in 2/3 patients with 1 in 10 patients having a change identified in the result. Only a small number of patients underwent surgery (19) and 42 patients died of a head injury-related death. A poor outcome was identified in 6.1% of the patient group. After further data analysis, a reduced conscious state, vomiting and loss of consciousness were found to predict a poor outcome. The most cost-effective strategy appeared to be that employed in the real world, compared with the strategy of CT imaging for all patients taking account of patient benefit and costs.

These results will help to inform ED clinicians and other health professionals how to manage this group of patients most effectively, improving patient care and hopefully help to reduce poor outcomes.

Funding

The study was funded by a National Institute for Health (NIHR) Research for Patient Benefit (RfPB) grant, Ref: PB-PG-0808-17148 (£249,000). It started in July 2011 and closed in March 2014 following a 9-month extension.