Journal Reading

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Journal Reading

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The Canadian CT Head Rule for patients with minor
head injury

• Stiell IG. Wells GA. Vandemheen K. Clement C.
  Lesiuk H. Laupacis A. McKnight RD. Verbeek R.
  Brison R. Cass D. Eisenhauer ME. Greenberg G.
  Worthington J.

The Lancet. Vol 357. May 5,2001
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Introduction

• Minor head injury - A patient with a history of
• Loss of consciousness
• Amnesia
• Disorientation
• A Glasgow Coma Scale score of 13-15.
• Use of CT for minor head injury has become
  increasely common (270000 cases in 1992 in North
  American), the US yield of CT for intracranial
  lesions in minor head injury is estimated to be
  quite low (0.7-3.7).

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Methods- Study setting and population

• A prospective cohort study in 10 Canadian
  community and teaching institutions.
• The research ethics committees of the study
  hospitals approved the protocol without the need
  for informed consent
• Inclusion criteria the patients having all of
  the following
• Blunt trauma to head resulting in witnessed LOC,
  definite amnesia, or witnessed disorientation
  (minor head injury)
• Initial ED GCS score of 13-15
• Injury within the past 24 h.

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Methods- Study setting and population

• Exclusion criteria
• Less than 16 years old
• Minimal head injury (ie, no LOC, amnesia, or
  disorientation)
• No clear history of trauma as the primary event
  (eg, primary seizure or syncope)
• An obvious penetrating skull injury or obvious
  depressed fracture
• Acute focal neurological deficit
• Unstable vital signs associated with major trauma
• A seizure before assessment in the ED
• A bleeding disorder or used oral anticoagulants
• Returned for reassessment of the same head injury
• Pregnancy

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Methods- Standardized patient assessment

• The physician assessors were trained in a 1 h
  session to assess patients for 22 standardized
  clinical findings from the history, general
  examination, and the neurological status.
• The data was recorded on sheets before the scan.
• A subset of patients were independently assessed
  by a second ED physicians to judge interobserver
  agreement.
• For pts transferred from a primary care hospital,
  study assessment were undertaken after arrival at
  the study site.

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Methods- Outcome measures and assessment

• The primary outcome - Need for neurological
  intervention.
• Death within 7 days secondary to head injury
• The need for any of the following procedures
  within 7 days craniotomy, elevation of skull
  fracture, intracranial pressure monitoring, or
  intubation for head injury (shown on CT).
• The secondary outcome - Clinically important
  brain injury, on CT.

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Methods- Outcome measures and assessment

• Clinically important brain injuries
• Any acute brain finding revealed on CT, which
  would normally require admission and nrudological
  follow-up
• Clinically unimportant brain injuries
• Neurologically intact
• On CT
• Solitary contusion less than 5 mm in diameter
• localized subarachnoid blood less than 1 mm thick
• smear subdural hematoma less then 4 mm thick
• isolated pneumocephaly, or closed depressed skull
  fracture not through the inner table.

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Methods- Outcome measures and assessment

• After the clinical exam, patients underwent
  standard CT (without contrast, cuts of 10 mm or
  less from the foramen magnum to the vertex,
  including soft tissue and bone windows) of the
  head according to the judgment of the treating
  physician.
• The CT scans were interpreted by qualified staff
  neuroradiologists who were unaware of the
  contents of the data collection sheet.

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Methods- Outcome measures and assessment

• All enrolled patients without imaging underwent
  the structured 14-day telephone proxy outcome
  measure administered by a registered nurse.
• Patients were classified as having no clinical
  important brain injury if they met all the
  following explicit criteria at 14 days.
• Headache abscent or mild, no complaints of memory
  or concentration problems, no seizure or focal
  motor findings, weighted error score of no more
  than 10 out of 28 on the Katzman Short
  Orientation-Memory-Concentration Tests, and had
  returned to normal daily activities.

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Results

• Time Oct, 1996 to Dec, 1999.
• 3121 pts were enrolled and 100 of these had
  complete assessment of the primary outcome
  measure, need for neurological intervention.
• 2078 (67) pts received CT of head (for
  assessment of the secondary outcome).
• 44 (1) required neurological intervention (4 pts
  died of their head injury)
• 254 (8) pts were judged to have clinically
  important brain injury
• 94 (4) pts were judged to have clinically
  unimportant lesions (mainly localized SAH or
  isolated contusion less than 5 mm in diameter).
• 1358 eligible pts were not enrolled by physicians

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Discussion

• In this rules, pts with minor head injury can be
  identified at 2 levels of risk.
• For pts with any one of high-risk factors Brain
  CT neurological intervention
• For pts with any one of medium-risk facors
  Brain CT for clinical important brain lesions but
  are not at a risk for needing neurological
  intervention.

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Discussion

• The simple rules are easy to use for the busy
  emergency physicians.
• The rules are both high sensitivity and
  specificity.

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Discussion

• In the USA, the opinions about the indication of
  brain CT in pts with minor head injury are
  divided into 3 groups.
• 1st group CT is indicated for all patients with
  minor head injury regardless of clinical findings
  primarily of neurosurgeons.
• 2nd group a very selective approach to use of CT
  in minor head injury neurosurgeons, ED
  physicians, radiologists.
• Even a normal CT in the ED dose not preclude
  later development of ICH.
• 3rd group no clear recommendations for use of CT
  in minor head injuries.

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Discussion - Haydel et al, Indications for CT in
patients with minor head injury, NEJM 2000
343100-05.

• Headache any head pain, whether diffuse or local
• Vomiting any emesis after the traumatic event
• An age over 60 years
• Drug or alcohol intoxication by history or PE
• Deficits in short-term memory persistent
  anterograde amnesia in a patient with an
  otherwise normal score on the Glasgow Coma Scale
• Physical evidence of trauma above the clavicles
  any external evidence of injury, including
  contusions, abrasions, lacerations, deformities,
  and signs of facial or skull fracture
• Seizure a suspected or witnessed seizure after
  the traumatic event

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Discussion - Haydel et al, Indications for CT in
patients with minor head injury, NEJM 2000
343100-05.

• Not reliable, sensitive, or specific enough to
  safely and efficiently.
• No assessment of their interobserver agreement.
• No assessment of some potentially valuable
  findings (mechanism of injury, chronic alcohol
  abuse, signs of basal skull fracture, signs of
  open skull fracture)
• Too few clinically important outcomes to measure
  sensitivity with a acceptable narrow 95 CI (the
  case no. of 909 was fairly large).
• Low specificity 77 pts with GCS of 15 would
  require CT.

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Discussion- the strength of this study

• Adherence to methodological standards for
  decision rules.
• Study participants were selected without bias.
• The order of CT was not based upon the subjective
  decision of individual physicians.
• Increasing generalisability (pts represented a
  wide spectrum of characteristics and sites).
• Explicit and appropriate methematical techniques.

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Discussion- the potential limitation

• The definition of clinically important brain
  injury made by neurosurgeons and ED physicians.
• The importance of the primary study outcome, need
  for neurological intervention the decision rule
  of this study is designed to improve patient care
  and depends upon and evidence-based approach
  rather than dealing with medicolegal concerns.
• Not all pts underwent CT all pts were fully
  assessed for the primary outcome measure, and all
  the remaining 1043 pts underwent 14-day telephone
  follow-up.
• Drug or ethanol ingestion is not a feature of
  this rule the data

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Discussion- the potential implications

• Patient care would be standardized and improved.
• A highly sensitive decision rule would reduce or
  eliminate the likelihood of patients being
  discharged from the ED with an undiagnosed ICH.
• Physicians working in smaller hospitals without
  CT scanners would have clear directions about
  when to transfer pts for a CT scan (pts with any
  of the high-risk factors).
• An accurate decision rule could lead to large
  savings for health-care systems.
• A 25-50 relative reduction of CT head use could
  be safely achieved.

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Thanks For Your Attention !