Introduction: Sex differences in coagulation have been well documented, but it is unknown if post-stroke coagulation factor levels differ by sex. High levels of Factor XI (FXI) and Factor XII (FXII) have been associated with increased incidence of acute ischemic stroke (AIS), especially in women.
Hypothesis: This study investigates the hypothesis that levels of FXI, FXII and Plasminogen Activating Inhibitor (PAI1) are different after AIS in men and women.
Methods: This was a retrospective study using a biomarker database of patients who presented to the emergency department with stroke. Sample collection occurred 24 hours after AIS onset. Plasma levels of FXI, FXII and PAI1 were assessed with ELISA in a population of 73 patients with no prior history of coagulation disorders, including 29 controls and 44 AIS patients confirmed by MRI, mean age = 68.7+/- 15.1, and 47% female. Log transformation was done before fitting the model. ANOVA was used to investigate the relationship between factor levels in sex and stroke. Tukey-Kramer multiple comparison tests were used for paired group comparisons.
Results: FXI levels were significantly higher in control subjects compared to AIS (p-value=0.007). FXI levels were also higher in females than in males, nearing statistical significance (p-value=0.053). PAI1 and FXII levels were not statistically different in men vs. women, or in control vs. AIS patients. Female controls had higher FXI levels than male AIS patients (0.487, 95% CI 0.085-0.889).
Conclusion: Stroke patients were found to have significantly lower levels of FXI compared to controls. This demonstrates that the pathological process of AIS may result in depletion of circulating plasma FXI at 24 hours after stroke onset. Overall, in stroke and control patients, there was a trend for females to have higher levels of FXI than men. No significant sex or stroke differences were found in FXII or PAI1 levels, likely due to sample size. Additional samples are being evaluated to determine if this stroke-induced decrease in FXI levels is associated with functional outcomes.