Background and purpose: In 6% to 9% of patients with subarachnoid hemorrhage (SAH), familial aggregation occurs; truly familial cases carry a worse prognosis than sporadic cases and raise the question of screening. If relatives have died from SAH, the family history is often the only available clue to the diagnosis, but the sensitivity and predictive value of such a history for SAH are unknown.
Methods: We contacted a next of kin for a consecutive series of patients who had died in the hospital of subarachnoid hemorrhage (n=20), intracerebral hemorrhage (n=22), or ischemic stroke (n=23) between 3 and 5 years previously, and we compared the diagnosis based on the history from this next of kin with the medical diagnosis confirmed by a CT scan.
Results: The positive predictive value of the diagnosis of "probable SAH" from the history in our study sample was 0.7; when adjusted for incidence rates in the general population it was 0.6 (95% confidence interval, 0.3 to 0.8). The sensitivity of the diagnosis based on the history was 0.5 (95% confidence interval. 0.3 to 0.7); 10 of the 20 cases of SAH were not identified.
Conclusions: The family history of SAH, without confirmation from medical documents, is an insufficiently accurate tool to prove or disprove the diagnosis of familial SAH.