Case Fatality in Patients With Aneurysmal Subarachnoid Hemorrhage in Finland

Although single-center studies have reported declining case fatality rates (CFRs) of aneurysmal subarachnoid hemorrhage (SAH), nationwide reports that also include sudden-death SAHs with long uninterrupted study periods have remained limited. Moreover, little is known about whether the time-dependent trends of SAH CFR differ by age and/or sex. Thus, we aimed to characterize the nationwide changes of SAH CFRs in Finland between 1998 and 2017.We used 2 externally validated nationwide registers to identify all hospitalized and nonhospitalized (sudden-death) aneurysmal SAH events in Finland during 1998-2017. In addition to overall 30-day CFRs, we determined annual proportions of sudden-death and 30-day CFRs among hospitalized patients with SAH. To estimate time-dependent trends, we calculated annual age-adjusted and sex-adjusted CFR changes (percent with 95% CIs).Between 1998 and 2017, we identified 9,443 cases with SAH (57.6% women), of which 2,245 (23.8%) died before hospitalization and 3,715 (39.3%) died within 30 days after SAH. Among the 7,198 hospitalized patients with SAH, the 30-day CFR was 20.4%. During the study period, the overall age-adjusted and sex-adjusted CFR declined by an average of 1.8% (1.1%-2.6%) per year. The decreases were especially notable in the proportion of sudden deaths among middle-aged (aged 40-64 years) and older (aged 65 years or older) women (2.9% [1.1%-4.7%] and 2.3% [0.7%-4.0%] per year, respectively) and in the CFRs of hospitalized young (younger than 40 years) and middle-aged women (9.1% [2.3%-15.7%] and 4.3% [2.3%-6.5%] per year, respectively). On the contrary, the 30-day CFR of older (aged 65 years or older) hospitalized men increased by 3.5% (0.7%-6.3%) per year, while the proportions of older men who died before hospitalization remained unchanged.The overall CFR of SAH seems to be decreasing, at least among women. The continued high CFR of hospitalized older men requires attention from clinicians and epidemiologists, especially if this trend is also common in other countries.