Initial misdiagnosis of aneurysmal subarachnoid hemorrhage: associating factors and its prognosis

Background: Predicting the fate of patients who are given a misdiagnosis of aneurysmal subarachnoid hemorrhage (aSAH) remains unclear. The purpose was to examine factors associated with initial misdiagnosis of aSAH and to investigate the impact of initial misdiagnosis of aSAH on clinical outcomes. Methods: Between January 2007 and December 2015, medical records and radiographic data for 3118 consecutive patients with aSAH were reviewed. There were 33 patients who had been documented with an initial misdiagnosis of aSAH, and all met the following criteria: (1) failure to correctly identify aSAH upon initial presentation to health care professionals; and 2) subsequently documented aSAH after the initial misdiagnosis. After applying exclusion criteria, remaining 2898 patients were included in the control group. Results: The most common cause of the misdiagnosis is failure to detect aSAH on the initial radiographic imaging. Misdiagnosis group showed lower initial Glasgow Coma Scale, better Hunt-Hess grade, and lower Fisher’s grade. Logistic regression analysis showed that initial HH grade (OR, 0.216; p = 0.014), initial Fisher’s grade (OR, 0.732; p = 0.036), and hospital type during initial contact (OR, 2.266; p = 0.042) were independently associated with misdiagnosis of aSAH. Conclusions: Patients with initially good HH grade, lower Fisher’s grade, and visiting non-teaching hospital for initial contact were at risk of being misdiagnosed. Misdiagnosis of aSAH in patients with initial good HH grade did affect clinical outcomes negatively. The rebleeding rate was not significantly different between two groups. However, the mortality rate due to rebleeding was higher in MisDx group than in non-MisDx group.