Mortality according to the cumulative time of systolic blood pressure in critically ill patients: a retrospective cohort study and propensity analysis (Preprint)

Abstract

Studies have shown a non-linear relationship between systolic blood pressure (SBP) and outcomes, with increased risk observed at both low and high blood pressure levels. However, the relationship between different SBP levels and outcomes in critically ill patients remains unclear.

We aimed to evaluate the association between the accumulated time of SBP levels and mortality in critically ill patients.

A retrospective analysis was conducted using data from Medical Information Mart for Intensive Care (MIMIC) III database, which includes more than 3,700,000 SBP records from 30,738 patients. The associations of cumulative time at 4 SBP ranges (<100, 100-120, 120-140, and ≥140 mmHg) with mortality (12-, 3-, 1-month mortality, and in-hospital mortality) were evaluated in this study. Restricted cubic splines and multivariable cox regression models were calculated to assess the association between the percentage of cumulative time levels of SBP (4 levels: <25%, 25-50%, 50-75%, ≥75%) and mortality after intensive care unit (ICU) admission. Additionally, SBP 120-140 mmHg subdivided into the percentage of accumulated time <25% (Group L) and ≥25% (Group M) subsets and separately underwent propensity score matching and subgroup analyses.

The risk of mortality appeared greater for time spent with an SBP <100 mmHg and lesser for time spent with an SBP 120-140 mmHg. Compared with level-1 of SBP <100 mmHg, level 4 has approximately a 3.4-fold increased risk of 12-month mortality. Compared with level-1 of SBP 120-140 mmHg, level-4 was associated with a lower adjusted risk of mortality at 12 months (OR, 0.66; CI, 0.50-0.87), 3 months (OR, 0.64; CI, 0.46-0.90), 1 months (OR, 0.52; CI, 0.33-0.83) and in-hospital (OR, 0.42; CI, 0.25-0.70). Similarly, Group M was decreased 12-month mortality after ICU admission, including analyses with propensity score matching and subgroup.

Cumulative time of SBP less than 100 mmHg is associated with increased mortality after ICU admission. More significantly, the cumulative time of SBP 120-140 mmHg was associated with better outcomes. Randomized trials are required to determine whether outcomes improve with interventions after ICU admission that maintain an SBP level at 120-140 mmHg.