Associated Factors of Pre-Anesthesia Blood Pressure Elevation in Elective Non-Cardiac Surgical Patients: A Case-Control Study Comparing Two Diagnostic Thresholds

Background: Pre-anesthesia blood pressure (BP) elevation frequently occurs in normotensive elective surgical patients and may disrupt perioperative safety. This study adopted two mainstream diagnostic criteria (absolute and relative thresholds) to define BP elevation, and integrated physical, laboratory and psychological indicators to systematically explore relevant associated factors. Methods: This case-control study enrolling a total of 528 non-cardiac surgical patients. Patients were divided into case (elevated pre-anesthesia BP) and control (normal pre-anesthesia BP) groups. Pre-anesthesia BP elevation was defined as absolute threshold (systolic BP [SBP] ≥140 mmHg and/or diastolic BP [DBP] ≥90 mmHg), and relative threshold (≥20% increase from baseline). Multivariable logistic regression was used to screen associated factors. Results: The incidence of pre-anesthesia BP elevation was 35.6% (n=188) under the absolute threshold and 28.2% (n=149) under the relative threshold. Multivariable analysis revealed that increasing age (absolute threshold: odds ratio [OR] 1.08, 95% confidence interval [CI] 1.05-1.10, relative threshold: OR 1.03, 95% CI 1.01-1.04), hyperlipemia (absolute threshold: OR 2.66, 95% CI 1.84-3.86, relative threshold: OR 1.49, 95% CI 1.18-1.88) and anxiety (absolute threshold: OR 1.17, 95% CI 1.10-1.25, relative threshold: OR 1.07, 95% CI 1.02-1.13) were correlated with BP elevation under both definitions (all p < 0.01). Under the absolute threshold, body mass index (BMI) (OR 1.12, 95% CI 1.03-1.21) and alcohol drinking (OR 2.74, 95% CI 1.55-4.84) were positively correlated (both p < 0.01), whereas prolonged sleep duration (2-4 hours: OR 0.37, 95% CI 0.15-0.95, 4-6 hours: OR 0.14, 95% CI 0.06-0.35, 6-8 hours: OR 0.12, 95% CI 0.04-0.34) was negatively correlated (all p < 0.05). Conclusion: Increasing age, hyperlipemia and preoperative anxiety are consistently associated with transient pre-anesthesia BP elevation under both criteria. Further studies are required to confirm causal links and verify whether intervening on these correlates can reduce perioperative BP fluctuations.