Association of Perioperative Hematocrit With Postoperative Neurological Complications in Adults Undergoing Revascularization Surgery for Moyamoya Disease: A Retrospective Cohort Study

OBJECTIVE: Hematocrit influences blood viscosity and cerebral oxygen delivery, but its perioperative significance in adults with moyamoya disease (MMD) remains unclear. This study evaluated the associations of preoperative hematocrit, postoperative hematocrit, and delta hematocrit, defined as preoperative minus postoperative hematocrit, with postoperative neurological complications following revascularization surgery. METHODS: This retrospective cohort study included 220 adults who underwent revascularization for MMD at a tertiary center in South Korea between 2012 and 2020. The primary analysis assessed the association between preoperative hematocrit and postoperative neurological complications. Secondary analyses examined postoperative hematocrit and delta hematocrit. Multivariable associations were estimated using Firth penalized logistic regression. Restricted cubic spline analyses were performed to assess potential nonlinear associations. RESULTS: Postoperative neurological complications occurred in 47 patients (21.4%). Higher preoperative hematocrit (odds ratio [OR]=1.17, 95% CI: 1.04-1.33; P=0.008) and postoperative hematocrit (OR=1.15, 95% CI: 1.04-1.29; P=0.005) were associated with complications after multivariable adjustment. Delta hematocrit was not associated with complications in linear analysis (OR=0.91, 95% CI: 0.80-1.01; P=0.081). An exploratory restricted cubic spline analysis did not identify a significant association between delta hematocrit and postoperative neurological complications (overall P=0.060). CONCLUSIONS: Higher preoperative and postoperative hematocrit levels were associated with postoperative neurological complications after multivariable adjustment; however, because the timing of the postoperative measurement relative to the onset of complications was uncertain, postoperative hematocrit should not be interpreted as a predictive variable. Perioperative change in hematocrit showed a more complex exploratory pattern after accounting for baseline hematocrit, but this finding requires confirmation in larger cohorts.