JAMA : the journal of the American Medical Association
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Three clinical decision rules were previously derived to identify patients with headache requiring investigations to rule out subarachnoid hemorrhage. ⋯ Among patients presenting to the emergency department with acute nontraumatic headache that reached maximal intensity within 1 hour and who had normal neurologic examination findings, the Ottawa SAH Rule was highly sensitive for identifying subarachnoid hemorrhage. These findings apply only to patients with these specific clinical characteristics and require additional evaluation in implementation studies before the rule is applied in routine clinical care.