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PL01: Multicentre before-after implementation study of the Ottawa subarachnoid hemorrhage strategy

  • J. J. Perry (a1), M. L.A. Sivilotti (a1), M. Emond (a1), C. M. Hohl (a1), H. Lesiuk (a1), J. Sutherland (a1), M. Khan (a1), K. Abdulaziz (a1), G. A. Wells (a1) and I. G. Stiell (a1)...
Abstract

Introduction: The Ottawa SAH Rule was developed to identify patients at high-risk for subarachnoid hemorrhage (SAH) who require investigations and the 6-Hour CT Rule found that computed tomography (CT) was 100% sensitive for SAH 6 hours of headache onset. Together, they form the Ottawa SAH Strategy. Our objectives were to assess: 1) Safety of the Ottawa SAH Strategy and its 2) Impact on: a) CTs, b) LPs, c) ED length of stay, and d) CT angiography (CTA). Methods: We conducted a multicentre prospective before/after study at 6 tertiary-care EDs January 2010 to December 2016 (implementation July 2013). Consecutive alert, neurologically intact adults with a headache peaking within one hour were included. SAH was defined by subarachnoid blood on head CT (radiologists final report); xanthochromia in the cerebrospinal fluid (CSF); >1x106/L red blood cells in the final tube of CSF with an aneurysm on CTA. Results: We enrolled 3,669 patients, 1,743 before and 1,926 after implementation, including 185 with SAH. The investigation rate before implementation was 89.0% (range 82.9 to 95.6%) versus 88.4% (range 85.2 to 92.3%) after implementation. The proportion who had CT remained stable (88.0% versus 87.4%; p=0.60), while the proportion who had LP decreased from 38.9% to 25.9% (p<0.001), and the proportion investigated with CTA increased from 18.8% to 21.6% (p=0.036). The additional testing rate (i.e. LP or CTA) diminishedfrom 50.1% to 40.8% (p<0.001). The proportion admitted declined from 9.8% to 7.3% (p=0.008), while the mean length of ED stay was stable (6.2 +/− 4.0 to 6.4 +/− 4.1 hours; p=0.45). For the 1,201 patients with CT 6 hours, there was an absolute decrease in additional testing (i.e. LP or CTA) of 15.0% (46.6% versus 31.6%; p<0.001). The sensitivity of the Ottawa SAH Rule was 100% (95%CI: 98-100%), and the 6-Hour CT Rule was 95.3% (95%CI: 88.9-98.3) for SAH. Five patients with early CT had SAH with CT reported as normal: 2 unruptured aneuryms on CTA and presumed traumatic LP (determined by treating neurosurgeon); 1 missed by the radiologist on the initial interpretation; 1 dural vein fistula (i.e. non-aneuyrsmal); and 1 profoundly anemic (Hgb 63g/L). Conclusion: The Ottawa SAH Strategy is highly sensitive and can be used routinely when SAH is being considered in alert and neurologically intact headache patients. Its implementation was associated with a decrease in LPs and admissions to hospital.

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Canadian Journal of Emergency Medicine
  • ISSN: -
  • EISSN: 1481-8035
  • URL: /core/journals/canadian-journal-of-emergency-medicine
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