Abstract P671: Association Between Liver Fibrosis and Postoperative Stroke

Introduction: Chronic liver disease is associated with aberrant hemostasis, resulting in an increased risk of clotting and bleeding. We hypothesized that liver fibrosis, a manifestation of progressive chronic liver disease, is associated with stroke among people who have been subjected to the hemostatic stress of surgery. Methods: We conducted a retrospective, multicenter cohort study using data from 680 hospitals participating in the American College of Surgeons National Surgical Quality Improvement Program (NSQIP), a prospective registry of 30-day outcomes. Quality measures, such as stroke, have been validated and have 95% inter-observer agreement. We included adults who underwent major surgery, except neurosurgery, from 2005-2016. The exposure was the Aspartate aminotransferase to Platelet Ratio Index (APRI) liver fibrosis score, calculated from preoperative aspartate aminotransferase and platelet count. The primary outcome was incident stroke, reported by NSQIP as a composite of ischemic and hemorrhagic stroke. We used multivariable Cox proportional hazards models to assess the relationship between APRI and incident stroke, adjusting for demographics, comorbidities, and surgical characteristics (surgical type and American Society of Anesthesiologists preoperative fitness classification). In a sensitivity analysis, we also adjusted for preoperative platelet count and coagulation indices. Results: Among 2,729,995 patients, the mean age was 57 (SD, 17) years and 58% were women. A total of 6,886 patients had stroke within 30 days (0.25%). In unadjusted analyses, a 1-point increase in APRI was associated with a 3% increased risk of stroke (HR, 1.03; 95% CI, 1.02-1.03). The association remained significant in models adjusted for comorbidities and surgical characteristics (HR, 1.02; 95% CI, 1.01-1.03). Sensitivity analyses also adjusted for platelet count and coagulation indices were consistent (HR, 1.03; 95% CI, 1.01-1.04). Conclusions: A liver fibrosis score calculated from routine preoperative laboratory data was independently, albeit modestly, associated with an increased risk of stroke within 30 days after surgery. Whether preoperative assessment of liver disease markers has clinical utility requires investigation.