Early blood pressure response index and mortality risk in cardiogenic shock: evidence from two critical care cohorts

Cardiogenic shock (CS) remains the leading cause of mortality in intensive care units (ICUs), with vasoactive agents frequently employed for haemodynamic support. However, existing scoring systems often fail to capture the dynamic circulatory responses to such interventions. The blood pressure response index (BPRI), a novel haemodynamic marker, has shown potential in reflecting treatment responsiveness. This study aims to assess the prognostic utility of BPRI for early risk stratification in patients with CS. We analysed adult CS patients admitted to intensive care units using data from the Medical Information Mart for Intensive Care IV (MIMIC-IV) and eICU Collaborative Research Database (eICU). The primary outcomes were ICU and in-hospital mortality. Early BPRI was defined as the ratio of the lowest mean arterial pressure to the vasoactive-inotropic score within the first 24 h of ICU admission. Multivariable Cox proportional hazards models were employed to evaluate the association between BPRI and mortality. Non-linear associations were assessed using restricted cubic spline analysis, and segmented Cox models were applied when appropriate. Discriminative performance of BPRI in combination with established scoring systems was evaluated and compared. Subgroup and sensitivity analyses were performed to validate the robustness of the findings. A total of 1,666 patients from the MIMIC-IV cohort (median age: 68.0 years; interquartile range [IQR]: 58.0–77.0; 61.2% male) and 164 patients from the eICU cohort (median age: 66.0 years; IQR: 54.0–74.0; 65.2% male) were included. In MIMIC-IV, the adjusted hazard ratios (HRs) for ICU and hospital mortality comparing the highest and lowest BPRI tertiles were 0.57 (95% CI: 0.45–0.72) and 0.55 (95% CI: 0.44–0.69), respectively. In the eICU cohort, the corresponding HRs were 0.33 (95% CI: 0.15–0.72) and 0.36 (95% CI: 0.19–0.70). Restricted cubic spline analysis revealed an L-shaped association between BPRI and mortality, with a threshold effect around a BPRI value of 3.0. Combining BPRI with traditional scoring systems improved discrimination for both ICU and hospital mortality. These findings remained robust across multiple subgroups defined by age, sex, comorbidities, and treatment interventions. These findings indicate that early BPRI may represent a practical and informative prognostic marker in cardiogenic shock, offering timely insights into haemodynamic response and facilitating early risk stratification.