Grant: Operating Grant

This study will validate, or confirm the accuracy, of two new ways to determine which headache patients seen in emergency require investigation for possible subarachnoid haemorrhage (SAH). One is the Ottawa SAH Rule which will determine which patients with severe headaches need any investigations. The second is the 6-Hour CT Rule, which says that patients who have a CT scan (a type of X-Ray) within 6 hours of headache onset do not need a lumbar puncture (LP) (where a needle is put into the lower back to get spinal fluid). SAH is a type of hemorrhagic stroke caused by a rupture of a brain aneurysm. One percent of emergency department visits for a headache have a SAH. Half of all patients who have a SAH die and of those who survive, almost half have permanent neurological symptoms. Currently SAHs are diagnosed using CT and LP. Once the accuracy of these rules has been confirmed, we will also conduct a targeted implementation study to determine if physicians will use these rules. During implementation, we will also further assess the safety of the rules, use of testing and the length of time patients spend in the emergency department. Given the need for a correct diagnosis and the cost and invasiveness of over-investigating patients, clinical decision rules, which physicians will use, are needed to determine which headache patients require evaluation and how best to investigate patients requiring evaluation.