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Clinical Decision Rules to Identify Patients at High Risk for Subarachnoid Hemorrhage

One of three rules might eliminate unnecessary evaluation of patients with acute headache.

Because subarachnoid hemorrhage (SAH) is a potentially devastating cause of acute headache, many patients with acute headache undergo extensive testing (e.g., computed tomography [CT], lumbar puncture) to rule it out. In this 5-year multicenter prospective Canadian study that involved nearly 2000 neurologically intact adults who presented with acute (peaking within 1 hour) nontraumatic headache, investigators sought to identify clinical characteristics that predicted SAH.

Overall, 130 patients had SAH. Sixteen clinical characteristics were associated significantly with SAH and were used to create three possible clinical decision rules:

• Rule 1: age >40, complaint of neck pain or stiffness, witnessed loss of consciousness, onset of headache with exertion
  
• Rule 2: arrival by ambulance, age >45, vomiting at least once, diastolic blood pressure >100 mm Hg
  
• Rule 3: arrival by ambulance, systolic blood pressure >160 mm Hg, complaint of neck pain or stiffness, age 45–55
  

For each rule, patients are investigated for SAH if one or more clinical characteristics in the rule are present. Retrospectively, each of the three rules had 100% sensitivity, and their specificities were between 28% and 39%.

Comment: Although these decision rules are promising, they must be validated in other populations before they are used routinely; indeed, the authors note that a prospective validation study is under way. But, in the meantime, the findings provide guidance: Patients who present with nontraumatic headaches that peak within 1 hour and who have any of the clinical characteristics mentioned in the rules above should be assessed carefully for SAH. As the authors note, validated rules "could allow clinicians to be more selective and accurate when investigating patients with headache" and lower use of CT and lumbar puncture.

— Paul S. Mueller, MD, MPH, FACP

Published in Journal Watch General Medicine November 9, 2010

Citation(s):

Perry JJ et al. High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: Prospective cohort study. BMJ 2010 Oct 28; 341:c5204. (http://dx.doi.org/10.1136/bmj.c5204)

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Reader Remarks:

Review and add to remarks on this article

• Subarachnoid Hemm
  Walter C Cotter, RI [retired], 12 Nov 2010 12:27 PM EST
  Specialty: Neurological Surgery
  In my many years of NS, I noted that many[?30%] of patients had a prodromal headache, not too severe, about... [more]
• SAH & expevsive test/(http://dx.doi.org/10.1136/bmj.c5204)
  Aliyah S Qureshi, witch Dr. Emile Mohler Curse, 12 Nov 2010 2:04 PM EST
  Specialty: Internal Medicine
  CT is still necessary to d/d to what is going on/ despite of history or age / silent Lucid intervel... [more]
• SAH, Tests and Lawyers
  M Z, 1 Dec 2010 8:16 AM EST
  Specialty: Neurological Surgery
  This criteria may work in Canada or Europe, but not in the US. Every patient with headache will be tested... [more]
• Rules can be broken
  Gary Kettas, Disabled, none, 1 Dec 2010 8:16 AM EST
  Specialty: Unspecified
  Just a reminder that most conditions' rules may be broken with unexpected anomalous exceptions that may be taken for granted... [more]
• eye opening research articles and stimulate thinking
  Peter M. Mativo, Aga Khan university hopsital, 1 Dec 2010 8:17 AM EST
  Specialty: Neurology
  eye opening research articles and stimulate thinking. Good and well thought neurology articles
• is your doctor hearing you
  Aliyah S Qureshi, va, 2 Dec 2010 11:10 AM EST
  Specialty: Internal Medicine
  what if doctor is a patient and his doctor is not listening?

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