Abstract
BACKGROUND: Several studies have attributed decreasing case fatality rates (CFRs) of aneurysmal subarachnoid hemorrhage (aSAH) to the gradually increasing use of endovascular treatment without considering improvements in other outcome-affecting factors. To assess the independent effect of a treatment modality on CFRs, we investigated CFR changes in a high-volume center rapidly transitioning from surgical to endovascular operations as the first-line treatment for all aSAH patients except those with middle cerebral artery (MCA) aneurysms. METHODS: We identified all surgically/endovascularly treated aSAH patients in Helsinki University Hospital (HUH) during 2012-2017. As the treatment shift occurred in 2015, we defined two treatment eras: surgical (2012-2014) and endovascular (2015-2017). We compared time-dependent changes in 1-year CFRs between non-MCA and MCA patients using a Poisson regression model. To analyze consistency in operation rates, we also identified sudden-death and conservatively treated aSAHs in the HUH catchment area via two externally validated registers. RESULTS: Of all 665 hospitalized aSAH cases in the HUH catchment area, 557 (84%) received operative treatment; 367 (66%) underwent surgical and 190 (34%) endovascular operations. Between the treatment eras, endovascular treatment for non-MCA cases increased from 21 to 79%, whereas 99% of the MCA cases were treated surgically during the whole study-period. Among the operatively treated patients, the 1-year CFRs decreased similarly in patients with non-MCA (42%; from 14 to 8%; adjusted risk ratio (aRR) = 0.66 (95% CI 0.37-1.19)) and MCA aneurysms (42%; from 15 to 9%; aRR = 0.66 (0.16-1.60)). The proportion of operatively treated patients, their clinical condition on admission, and amount of bleeding on the first CT-scan remained unchanged over time. CONCLUSIONS: We found similar CFR decreases in aSAH groups with and without undergoing a fast transition from surgery to endovascular operations, providing real-world evidence on the small independent effect of endovascular treatment on the decreasing CFRs in high-volume centers.