High risk clinical characteristics for subarachnoid haemorrhage in patients with acute headache: prospective cohort study

In this paper by Jeffrey J Perry and colleagues (BMJ 2010;341:c5204, doi:10.1136/bmj.c5204), the “more than” signs (>) in the box listing the three proposed rules should all be “more than or equal to” signs (≥). Therefore in rule 1 the age should be “age ≥40”; in rule 2 the age should be “age ≥45” and the diastolic blood pressure should be “≥100 mm Hg”; and in rule 3 the systolic blood pressure should be ≥160 mm Hg.