Safety of Modified Nimodipine Dosing in Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND Nimodipine improves outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). However, the impact of alternative dosing strategies on outcome remains unclear. METHODS We performed a retrospective cohort study of consecutive patients admitted with aSAH to an academic referral center from 2016-2019. We included patients with a confirmed aneurysmal cause who received nimodipine, while excluding those who died or had withdrawal of life-sustaining treatment within 24 hours of admission. Univariable and multivariable modified Poisson regression models were used to identify predictors of using modified nimodipine dosing (30 mg every 2 hours) versus standard dosing (60 mg every 4 hours). We used inverse probability weighted (IPW) and modified Poisson regression models to estimate adjusted risk ratios (RR) for outcome measures, with poor outcome defined as a modified Rankin Scale (mRS) 4-6 at 3-months. RESULTS We identified 175 aSAH patients who met our eligibility criteria (mean age 57 years [SD 13.2], 62% female, 73% white), of whom 49% (n=86) received modified nimodipine dosing. A modified dose was used more frequently in women (RR 2.08, 95% CI 1.11-3.89; p=0.02), patients with vasospasm (RR 3.47, 95% CI 1.84-6.51; p<0.001) and those who required vasopressors (RR 1.73, 95% CI 1.3-2.32; p<0.001). However, modified dosing was not associated with poor functional outcome (IPW RR 1.1, 95% CI 0.8-1.4, p=0.65). CONCLUSION A modified dosing regimen of nimodipine is well-tolerated and may not be associated with worse functional outcome. Prospective studies are needed to better assess the relationship between nimodipine dosing and outcomes in aSAH patients.