The Times They Are a-Changin': Increasing Complexity of Aneurysmal Subarachnoid Hemorrhages in Patients Treated from 2004 to 2018.

[BACKGROUND] Nationwide study results have suggested varying trends in the incidence of aneurysmal subarachnoid hemorrhage (aSAH) over time. Herein, trends over time for aSAH treated at a quaternary care center are compared with low-volume hospitals.

[METHODS] Cases were retrospectively reviewed for patients with aSAH treated at our institution. Trend analyses were performed on the number of aSAH hospitalizations, treatment type, Charlson Comorbidity Index (CCI), Hunt and Hess grade, aneurysm location, aneurysm type, and in-hospital mortality. The National Inpatient Sample (NIS) was queried to compare the CCI scores of our patients with those of patients in low-volume hospitals (<20 aSAH/year) in our census division.

[RESULTS] Some 1248 patients (321 during 2004-2006; 927 during 2008-2018) hospitalized with aSAH were treated with endovascular therapy (489, 39%) or microsurgery (759, 61%). A significant downtrend in the annual aSAH caseload occurred (123 patients in 2004, 75 in 2018, P < 0.001). A linear uptrend was observed for the mean CCI score of patients (R  = 0.539, P < 0.001), with no change to in-hospital mortality (R  = 0.220, P = 0.24). Mean (standard deviation) CCI for small-volume hospitals treating aSAH within our division was significantly lower than that of our patient population (1.8 [1.6] vs 2.1 [2.0]) for 2012-2015.

[CONCLUSIONS] A decreasing number of patients were hospitalized with aSAH throughout the study. Compared with patients with aSAH admitted in 2004, those admitted more recently were sicker in terms of preexisting comorbidity and neurologic complexity. These trends could be attributable to the increasing availability of neurointerventional services at smaller-volume hospitals capable of treating healthier patients.