Sex-specific associations of preoperative serum uric acid levels with mortality and morbidity in non-cardiac surgeries: a single-center retrospective study.

Background: The sex-specific association between serum uric acid (SUA) levels and postoperative outcomes in elective non-cardiac surgery remains unclear. This study aimed to identify sex-specific SUA thresholds and their impact on short- and long-term outcomes.

Methods: A retrospective analysis of 295,267 patients (2012-2021) undergoing non-cardiac surgery was conducted. Patients were stratified by preoperative SUA levels: for males (< 4 to ≥ 9 mg/dl) and females (< 3 to ≥ 8 mg/dl), with mid-range levels as reference. Mortality (30 d to overall) and complications were assessed using Cox and logistic regression. Cubic splines evaluated nonlinear trends, with subgroup analyses by age and surgical risk.

Results: SUA levels exhibited a nonlinear, sex-specific association with postoperative outcomes. The estimated lower-risk SUA range was 5.08-7.63 mg/dl in males and 3.34-5.35 mg/dl in females. In Cox and spline analyses, a U-shaped association between SUA and mortality was observed in both sexes, with significant risks at both low (< 4 mg/dl) and high (≥ 9 mg/dl) levels in males, and predominantly at low levels (< 3 mg/dl) in females. The types of complications varied subtly between sexes. Within SUA ranges of 4-6 mg/dl (males) and 3-4 mg/dl (females), composite and specific complication risks were lower than at either extreme, showing a protective effect, with reduced risk of acute kidney injury (AKI) in males and pneumonia in females. Additionally, extreme SUA levels were significantly associated with increased mortality and complications, particularly in low-risk surgical patients.

Conclusions: Preoperative SUA levels show a nonlinear, sex-specific association with postoperative outcomes, highlighting the need for sex- and risk-based perioperative stratification.