Sensitivity of proposed clinical decision rules for subarachnoid haemorrhage: An external validation study.
OBJECTIVE
Subarachnoid haemorrhage (SAH) is an uncommon but important cause of sudden-onset headache. Three clinical decision rules (CDRs) for investigation in sudden headache have been proposed, but concerns were raised about the generalisability of some variables. Our aim was to determine what proportion of patients with confirmed SAH has the identified high-risk factors and the sensitivity of the proposed CDR in an Australasian cohort.


METHODS
This is a retrospective cohort study of alert and neurologically intact adult patients with confirmed SAH attending two community teaching hospitals between 2000 and 2011. The outcomes of interest were the proportion of patients with each high-risk criterion (descriptive statistics) and sensitivity of each proposed CDR (%, interquartile range [IQR]).


RESULTS
There were 59 confirmed SAH that met the inclusion criteria. Sensitivity of proposed CDR 1 was 96.6% (95% confidence interval [CI] 88.5-99.1%), sensitivity of proposed CDR 2 was 100% (95% CI 93.9-100%) and sensitivity of proposed CDR 3 was 89.8% (95% CI 79.5-95.3%). The addition of vomiting to the criteria in CDRs 1 and 3 increased the sensitivity of both these CDRs to 100%.


CONCLUSIONS
CDR 2, or the refinement of CDRs 1 and 3 with the inclusion of at least one episode of vomiting as a criterion, has very high sensitivity. Although unlikely to reduce CT scan rates for patients in whom there is a clinical suspicion of SAH, they might be useful in guiding which patients require further testing (e.g. lumbar puncture) after a negative CT scan.
Joseph Epstein Centre for Emergency Medicine Research, Western Health, Melbourne, Victoria, Australia; NorthWest Academic Centre, The University of Melbourne, Melbourne, Victoria, Australia.
Anne-Maree
AM
Kelly
Sharon
S
Klim
Simon
S
Edward
Nicola
N
Millar
D000328:Adult; D001315:Australia; D003661:Decision Support Techniques; D004636:Emergency Service, Hospital; D005260:Female; D006261:Headache / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D019547:Neck Pain / Q000175:diagnosis / Q000209:etiology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000175:diagnosis* / Q000628:therapy
clinical decision rule; headache; subarachnoid