In Reply: Nighttime Treatment of Ruptured Intracranial Aneurysms are Associated With Poor Outcomes

To the Editor: We appreciate the letter by Dr Yu et al1 regarding our recent article titled, “Nighttime Treatment of Ruptured Intracranial Aneurysms Are Associated With Poor Outcomes.”2 Treatment timing plays a critical role in the management of ruptured intracranial aneurysms (RIAs) and may significantly influence patient outcomes. While immediate intervention is preferred to reduce the risk of rebleeding, determining the optimal timing remains complex and multifactorial. The aim of our study was to evaluate the impact of treatment timing on patient outcomes. In our retrospective single-center study of 493 patients treated within 24 hours, we categorized treatment as daytime (10 am-7 pm) vs nighttime (10 pm-7 am) and on-hours (7 am-7 pm) vs off-hours (7 pm-7 am). Our analysis revealed that nighttime treatment was associated with poorer outcomes (60.0% vs 72.0%, favorable modified Rankin Scale 0-2, OR: 0.50, 95% CI: 0.28-0.91) in multivariate analysis (P = .023), whereas off-hours treatment had no significant effect. These findings suggest that nighttime treatment may influence patient prognosis, potentially due to factors such as operator fatigue or resource availability. We appreciate Yu et al's insightful perspective and would be very interested in seeing data from their center on patient outcomes based on treatment timing. A comparison across institutions could help determine the generalizability of our findings. If similar trends emerge, they would reinforce the significance of treatment timing in RIA management, whereas differing results might highlight institution-specific factors influencing outcomes. To clarify, in our study, “treatment” specifically refers to aneurysm treatment, whereas hydrocephalus management was addressed separately when necessary. We fully agree that patients with Grade V World Federation of Neurological Surgeons (WFNS) scores have a poor prognosis. In our series, 48 patients presented with WFNS 5 and only 11 (22.9%) achieved a favorable outcome (modified Rankin Scale 0-2). Further research is needed to better understand the factors contributing to these outcomes. An important consideration is the influence of initial severity on outcomes and treatment delay. We acknowledge that nighttime patients had higher rates of midline shift hematomas (14.1% vs 6.3%, P = .01) and pretreatment rebleeding (5.1% vs 2.9%), which may have contributed to poorer outcomes. However, other clinical indicators, such as pupillary dilation at admission, did not differ significantly between groups (7.7% nighttime vs 2.7% daytime, P = .58). In addition, the association between nighttime treatment and worse outcomes remained significant in multivariate analysis, independent of factors reflecting disease severity, such as WFNS grade and hematoma presence. This suggests that treatment timing may have an effect beyond initial clinical severity. Regarding admission-to-treatment time, we agree that shorter times at night may reflect the need for immediate intervention due to larger hematomas or greater clinical instability. However, while some centers may benefit from increased OR availability at night, factors such as provider fatigue, resource allocation, and team composition may still affect outcomes differently across institutions. The choice between surgical and endovascular intervention is multifactorial and varies across institutions based on expertise, available technology, and patient-specific factors. In our study, endovascular treatment was performed in 48.9% (203/415) of daytime cases and 47.4% (37/78) of nighttime cases (P = .81). We included treatment modality as a variable in our multivariate analysis, and it was not significantly associated with favorable outcomes (OR: 1.02, 95% CI: 0.69-1.50, P = .92). Therefore, differences in treatment modality alone do not account for the effect of nighttime vs daytime treatment. In addition, we appreciate the important point regarding surgeon expertise and institutional support. At our center, dedicated neurosurgical teams are available around the clock; however, differences in surgeon experience, fatigue, and team composition may still contribute to variations in nighttime outcomes. A deeper understanding of these procedural and provider-related factors is crucial for optimizing RIA management. Beyond initial condition severity, factors such as operating room availability, staffing, and surgeon experience likely influence treatment outcomes. Our study provides an initial exploration of the impact of surgical timing on RIA prognosis; however, we recognize that a more comprehensive, multicenter approach is necessary to validate these findings and account for institutional variability. Future multicenter studies with detailed assessments of workflow efficiency, team composition, and surgeon experience across different time periods will be essential for refining best practices in RIA management.