title: The risk of intra-cranial haemorrhage in those presenting late to the ED following a head injury: a systematic review.
abstract: BACKGROUND
  Head injury represents an extremely common presentation to emergency departments (ED), but not all patients present immediately after injury. There is evidence that clinical deterioration following head injury will usually occur within 24 h. It is unclear whether this means that head injury patients that present in a delayed manner, especially after 24 h, have a lower prevalence of significant traumatic injuries including intra-cranial haemorrhages.
  
  
  METHODS
  A systematic review protocol was designed with the aim of systematically identifying and evaluating studies in delayed ED presentation head injury populations in order to establish whether the prevalence of significant intra-cranial injury was affected by delay in presentation. Two independent researchers assessed retrieved studies for inclusion against pre-determined inclusion criteria. Studies had to be conducted in ED head injury populations presenting in a delayed manner, and report a measure of prevalence of traumatic CT abnormality as an outcome.
  
  
  RESULTS
  Three studies were eligible for inclusion. They were all of poor methodological quality, and heterogeneity prevented meta-analysis. The reported prevalence of traumatic intra-cranial injury on CT was between 2.2 and 6.3%. This is generally lower than reported in the literature for non-delayed presentation head injury populations.
  
  
  CONCLUSIONS
  Available evidence suggests that head injury patients who present in a delayed fashion to the ED may have lower rates of intra-cranial injury compared to non-delayed head injury patients. However, the evidence is sparse and it is of too low quality to guide clinical practice. Further research is required to help the clinical risk assessment of this group.
  
  
  BACKGROUND
  
  CRD42015016135.
authors.affiliation: Emergency Department, Hull Royal Infirmary, Anlaby Road, Hull, HU3 2JZ, UK. cm444@doctors.org.uk.
authors.forename: Carl
authors.initials: C
authors.lastname: Marincowitz
authors.affiliation: Emergency Department, Hull Royal Infirmary, Anlaby Road, Hull, HU3 2JZ, UK. Christopher.Smith@hey.nhs.uk.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Smith
authors.affiliation: Emergency Department, Hull Royal Infirmary, Anlaby Road, Hull, HU3 2JZ, UK. William.Townend@hey.nhs.uk.
authors.forename: William
authors.initials: W
authors.lastname: Townend
mesh_terms: D006259:Craniocerebral Trauma / Q000150:complications* / Q000473:pathology; D057210:Delayed Diagnosis / Q000009:adverse effects* / Q000517:prevention & control; D004636:Emergency Service, Hospital; D006801:Humans; D020198:Intracranial Hemorrhage, Traumatic / Q000175:diagnosis / Q000209:etiology*; D059906:Neuroimaging / Q000379:methods*; D017410:Practice Guidelines as Topic; D015995:Prevalence; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed