Title: Ottawa Rules for Subarachnoid Hemmorhage (SAH)<br/>Author: Feras Khan<br/><a href='http://umem.org/profiles/faculty/1145/'>[Click to email author]</a><hr/><p>
<strong>Ottawa Rules for Subarachnoid Hemmorhage (SAH)</strong></p>
<p>
<strong>Background</strong></p>
<ul>
<li>
Headache is a common reason for ER visits</li>
<li>
1-3% of headaches are SAH</li>
<li>
Misdiagnosis of SAH can be fatal</li>
<li>
Lumbar puncture can be a painful/time-consuming procedure</li>
<li>
Goal is to design a decision rule to help guide the clinician</li>
</ul>
<p>
<strong>Design</strong></p>
<ul>
<li>
Multi-center study at ten Canadian emergency departments.</li>
<li>
2131 adults with a headache peaking within 1 hour and no neurologic deficits</li>
<li>
Non-traumatic headaches only; GCS of 15 required</li>
<li>
SAH defined as: 1. CT evidence of SAH; 2. Xanthochromia in CSF; or 3. RBCs in the final tube of CSF, <strong><em>WITH</em></strong> positive angiography findings.</li>
</ul>
<p>
<strong>Results</strong></p>
<p>
132 (6.2%) had SAH</p>
<p>
Decision rule including any:</p>
<ol>
<li>
age 40 years or older</li>
<li>
neck pain or stiffness</li>
<li>
witnessed LOC</li>
<li>
onset during exertion</li>
</ol>
<p>
Had 98.5% sensitivity (95% CI, 94.6%-99.6%) and 27.5% specificity (95% CI, 25.6%-29.5%)</p>
<p>
Adding “thunder-clap” headache and “limited neck flexion on examination” (inability to touch chin to chest or raise the head 8cm off the bed if supine) resulted in 100% (95% CI, 97.2%-100%) sensitivity.</p>
<p>
The rule was then evaluated using a bootstrap analysis on old cohort data to validate the rule.</p>
<p>
<strong>Conclusion/Limitations</strong></p>
<ul>
<li>
Exciting new rule for SAH that needs to be validated in a new, independent cohort</li>
<li>
The rule may not decrease the rate of investigation (CT, LP, or both)</li>
<li>
It may decrease the amount of SAH that are missed on first visit to the ER</li>
<li>
Limited by narrow criteria for inclusion in the rule/not meant for other causes of headache</li>
<li>
See the JAMA editorial with the article for a nice discussion of the difficulties with decision making rules.</li>
<li>
<div class="label">
The rule:</div>
<div class="caption">
The Ottawa SAH Rule</div>
<ul class="simple" sizcache="1" sizset="10">
<li>
<p class="para">
For alert patients older than 15 y with new severe nontraumatic headache reaching maximum intensity within 1 h</p>
</li>
<li>
<p class="para">
Not for patients with new neurologic deficits, previous aneurysms, SAH, brain tumors, or history of recurrent headaches (≥3 episodes over the course of ≥6 mo)</p>
</li>
<li>
<p class="para">
Investigate if ≥1 high-risk variables present:</p>
</li>
</ul>
<ol class="order" sizcache="1" sizset="11">
<li>
<p class="para">
Age ≥40 y</p>
</li>
<li>
<p class="para">
Neck pain or stiffness</p>
</li>
<li>
<p class="para">
Witnessed loss of consciousness</p>
</li>
<li>
<p class="para">
Onset during exertion</p>
</li>
<li>
<p class="para">
Thunderclap headache (instantly peaking pain)</p>
</li>
<li>
<p class="para">
Limited neck flexion on examination</p>
</li>
</ol>
<p class="para">
</p>
</li>
</ul>
<p>
</p>
<fieldset><legend>References</legend>
<h1 class="aTitle" nodeindex="3">
<span id="scm6MainContent_lblArticleTitle">Clinical Decision Rules to Rule Out Subarachnoid Hemorrhage for Acute Headache</span></h1>
<div class="authorSection sans" id="scm6MainContent_dvAuthorSection" nodeindex="4">
<span class="authorNames" id="scm6MainContent_lblAuthors">Jeffrey J. Perry, MD, MSc<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_0"><font size="2">1</font></sup>; Ian G. Stiell, MD, MSc<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_1"><font size="2">1</font></sup>; Marco L. A. Sivilotti, MD, MSc<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_2"><font size="2">5,6</font></sup>; Michael J. Bullard, MD<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_3"><font size="2">11</font></sup>; Corinne M. Hohl, MD, MHSc<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_4"><font size="2">7</font></sup>; Jane Sutherland, MEd<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_5"><font size="2">4</font></sup>; Marcel Émond, MD, MSc<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_6"><font size="2">8</font></sup>; Andrew Worster, MD<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_7"><font size="2">9</font></sup>; Jacques S. Lee, MD, MSc<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_8"><font size="2">10</font></sup>; Duncan Mackey, MD<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_9"><font size="2">11</font></sup>; Merril Pauls, MD<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_10"><font size="2">12</font></sup>; Howard Lesiuk, MD<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_11"><font size="2">3</font></sup>; Cheryl Symington, RN, ENCC<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_12"><font size="2">1</font></sup>; George A. Wells, PhD<sup id="scm6MainContent_rptAuthors_supAuthorAffiliations_13"><font size="2">2</font></sup> </span></div>
<div class="disclosures" id="scm6MainContent_divDisclosures" nodeindex="5" sizcache="24" sizset="38">
<a class="disclosureLink special" href="http://jama.jamanetwork.com/article.aspx?articleID=1741823#" id="jama.jamanetwork.com/article.aspx?articleid=1741823#-scm6MainContent_divDisclosures" jquery16407379856813280448="251">[<span class="spanPlus">+</span><span class="spanMinus" style="display: none">-</span>] Author Affiliations</a>
<div class="disclosureText" id="scm6MainContent_DisclosureAndother">
<span id="scm6MainContent_lblClientName"><i>JAMA. </i>2013;310(12):1248-1255. doi:10.1001/jama.2013.278018. </span></div>
<div class="disclosureText">
</div>
<div class="disclosureText">
<span><a href="http://jama.jamanetwork.com/article.aspx?articleID=1741799">http://jama.jamanetwork.com/article.aspx?articleID=1741799</a></span></div>
</div>
<p>
</p>
</fieldset><fieldset><legend>Attachments</legend>
ottawa_editorial.pdf (109 Kb)<br/><a href='http://umem.org/files/uploads/1311191832_ottawa_editorial.pdf' target='_blank'>http://umem.org/files/uploads/1311191832_ottawa_editorial.pdf</a><br/><br/></fieldset>