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 to 2019. Patients with a confirmed aneurysm cause who received nimodipine were included; patients who died or had withdrawal of life-sustaining treatment within 24 hours of admission were excluded. 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). Inverse probability weighted and modified Poisson regression models were used to estimate adjusted risk ratios (RRs) for outcome measures, with poor outcome defined as modified Rankin Scale score 4-6 at 3 months. RESULTS: We identified 175 patients with aSAH who met eligibility criteria (mean [SD] age = 57 [13.2] years, 62% female, 73% White); 49% (n = 86) received modified nimodipine dosing. A modified dose was used more frequently in women (RR 2.08, 95% confidence interval [CI] 1.11-3.89, P = 0.02), patients with vasospasm (RR 3.47, 95% CI 1.84-6.51, P < 0.001), and patients who required vasopressors (RR 1.73, 95% CI 1.3-2.32, P< 0.001). Modified dosing was not associated with poor functional outcome (inverse probability weighted AR 1.1, 95% CI 0.8-1.4, P = 0.65). CONCLUSIONS: Modified dosing 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 patients with aSAH.