Re-Evaluating Risk Factors, Incidence, and Outcome of Aneurysmal and Non-Aneurysmal Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is one of the world's most life-threatening types of stroke. SAH can be classified into two main categories, aneurysmal (aSAH) and non-aneurysmal SAH (naSAH). In the present study, we aimed to prospectively evaluate SAH and its subcategories incidences, risk factors, complications, and outcomes in central Iran.

All SAH patients diagnosed between 2016 and 2020 were included in Isfahan SAH Registry. Demographic, clinical characteristics, incidence rates (based on age categories), and laboratory/imaging findings were collected and compared between aSAH and naSAH subgroups. Complications during hospital stay and outcomes were also analyzed. Binary logistic regression analysis was performed to investigate the predictors of aSAH versus naSAH. Kaplan-Meier curves and Cox regression were used to evaluate the survival probability.

A total of 461 SAH patients were included through Isfahan SAH Registry. The SAH annual incidence rate was 3.11 per 100,000 person-years. aSAH had higher incidence rate than naSAH (2.08/100,000 vs. 0.9/100,000 person-years, respectively). In-hospital mortality was 18.2%. Hypertension (P = 0.003) and smoking (P = 0.03) were significantly associated with aSAH, whereas diabetes mellitus (P < 0.001) was more associated with naSAH. After Cox regression analysis, there were higher hazard ratios for reduced in-hospital survival in conditions including altered mental status, Glasgow Coma Scale ≤13, rebleeding, and seizures.

This study provided an updated estimation of SAH and its subgroups incidences in central Iran. Risk factors for aSAH are comparable to the ones reported in the literature. It is noteworthy that diabetes mellitus was associated with a higher incidence of naSAH in our cohort.