--study by Ottawa docs, Perry et al. reviewed nicely in an AAEM/Common Sense article (see reference)
--tried to identify a set of clinical characteristics to make a decision rule for those who need SAH workup
BASIC STRUCTURE:
--1,999 patients, 130 diagnosed with SAH
--SAH diagnosis defined by +CT, xanthrochromia, or >5 x 10^6/L RBCs + aneurysm/AVM on cerebral angiography
--included:
- adults (>16 yo)
- chief complaint = headache
- GCS 15
- non-traumatic
- peak intensity of HA within 1 hr
- >2 wks after symptom onset
- prior SAH
- previous CT and/or LP workup
- 3 similar HA's within past six months
- papilledema/focal neuro symptom
- prior hydrocephalus or cerebral neoplasm
RULES THEY CAME UP WITH:
--all have sensitivity 100%, but specificity sucked (28-39%)
--the rules (each set works to help rule-out SAH):
- age >40, neck pain/stiffness, witnessed LOC, DBP > 100mmHg
- arrival by EMS, age>45, vomiting, DBP > 100
- arrival by EMS, age 45-55, neck pain/stiffness, SBP > 160
BOTTOM LINE:
--nice study, helps think about why we do what we do, but isolated population
--the extra H&P details (age, BP, vomiting, neck pain/stiffness, etc.) are not very specific for SAH, but together might be sensitive (reminds me of appendicitis)
--not ready for primetime just yet, but food for thought
Submitted by S. Lee.
Reference(s): AAEM/RSA review, picture
