Exploring the Optimal Range of Blood Pressure in Elderly Sepsis Patients: A Retrospective Study Based on MIMIC-IV Data

Objective To explore the optimal range of blood pressure (BP) in elderly sepsis patients. Methods A retrospective case-control study was conducted. Demographic information, coexisting illnesses, vital signs, laboratory parameters, critical illness scores, and clinical treatment information for elderly sepsis patients were extracted from the Medical Information Mart for Intensive Care-IV (MIMIC-IV). Restricted cubic spline (RCS) analysis was employed to examine and visualize the nonlinear relationship between blood pressure and the incidences of in-hospital mortality and atrial fibrillation. Optimal systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) ranges were identified, and their association with 28-day mortality was validated using Cox regression analysis, propensity score matching (PSM), inverse probability weighting (IPTW), doubly robust model estimation (DR), and Kaplan–Meier survival curves (K-M). Results A total of 2,253 patients met the inclusion criteria, of whom 516 (22.9%) died during hospitalization and 1,087 (48.2%) experienced atrial fibrillation during hospitalization. Restricted cubic spline analysis revealed a nonlinear, L-shaped relationship between blood pressure and in-hospital mortality among elderly sepsis patients. When atrial fibrillation was used as the endpoint, the upper limit of blood pressure was constrained. The optimal SBP, DBP and MAP ranges for elderly sepsis patients were 108–118, 51–57, and 69–74 mmHg, respectively. Further statistical models confirmed that patients within the optimal blood pressure range exhibited decreased 28-day mortality compared to those outside this range [optimal blood pressure group: SBP (108–118 mmHg): Cox regression analysis: hazard ratio (HR) = 0.76, 95% confidence interval (CI) 0.64–0.91, P = 0.002; PSM: HR = 0.78, 95% CI 0.64–0.95, P = 0.015; IPTW: HR = 0.79, 95% CI 0.65–0.95, P = 0.015; DR: HR = 0.78, 95% CI 0.64–0.96, P = 0.018; DBP (51–57 mmHg): Cox regression analysis: HR = 0.79, 95% CI 0.67–0.95, P = 0.010; PSM: HR = 0.72, 95% CI 0.64–0.88, P = 0.001; IPTW: HR = 0.80, 95% CI 0.66–0.96, P = 0.015; DR: HR = 0.81, 95% CI 0.67–0.98, P = 0.032; MAP (69–74 mmHg): Cox regression analysis: HR = 0.83, 95% CI 0.69–0.99, P = 0.044; PSM: HR = 0.78, 95% CI 0.64–0.95, P = 0.016; IPTW: HR = 0.82, 95% CI 0.67–0.99, P = 0.040; DR: HR = 0.85, 95% CI 0.67–1.07, P = 0.172]. K–M survival analysis demonstrated that patients within the optimal blood pressure range had a higher probability of survival than those outside the range (SBP: Log-Rank test: χ² = 4.9, P = 0.0268; DBP: Log-Rank test: χ² = 5.06, P = 0.0244; MAP: Log-Rank test: χ² = 7.76, P = 0.00533). Conclusions During hospitalization, both elevated and reduced blood pressure levels in elderly sepsis patients are associated with an increased risk of mortality. The optimal ranges for SBP, DBP, and MAP in elderly sepsis patients are 108–118, 51–57, and 69–74 mmHg, respectively.