Association Between Blood Pressure Response Index and Prognosis in Patients with Septic Shock Caused by Pneumonia

Background No noninvasive index exists to assess vasopressor responsiveness for maintaining blood pressure in severe pneumonia-induced shock. This study evaluated the association between the blood pressure response index (BPRI) and prognosis in such patients. Methods A mixed retrospective and prospective cohort study analyzed clinical data from patients admitted to tertiary hospitals between January 2018 and January 2025. BPRI is the ratio between the mean arterial pressure and the vasoactive inotropic score. Cox regression analysis assessed the impact of BPRI on mortality risk, while Kaplan—Meier curves compared 30-day cumulative survival rates across BPRI tertiles. The receiver operating characteristic (ROC) curves evaluated BPRI's predictive accuracy for mortality. Restricted cubic spline (RCS) analysis explored potential nonlinear relationships between BPRI and mortality risk. Results The retrospective cohort included 618 patients, with 332 (52.7%) fatalities. In the prospective cohort, 65 patients were enrolled, with 30 (46.2%) death. Cox regression analysis of the retrospective dataset indicated that higher BPRI values correlated with lower mortality risk (adjusted hazard ratio [HR]= 0.843, 95% confidence interval [CI] [0.811, 0.877]). The ROC analysis demonstrated that BPRI predicted 30-day mortality (area under the curve [AUC] = 0.7404, 95%=[0.7018,0.7790]) more accurately than the vasoactive inotropic score (AUC=0.7034, 95%CI = [0.6627,0.7440]) and mean arterial pressure (AUC=0.6638, 95%CI = [0.6201,0.7075]), consistent with prospective findings. The RCS analysis revealed a nonlinear relationship between BPRI and mortality risk, with a cutoff value of 9.05. Conclusion A lower BPRI was significantly associated with increased mortality risk, following a nonlinear pattern. BPRI demonstrated substantial predictive value for severe pneumonia-induced shock.