Sex differences in blood pressure variability during critical illness: a retrospective cohort study

Higher blood pressure variability (BPV) has been associated with adverse cardiovascular events in various clinical settings, but its effects during critical illness remain unclear. There have been observed disparities in risk-adjusted mortality between females and males in the intensive care unit (ICU) and it is possible that BPV contributes to the underlying mechanistic physiology.

We aimed to examine whether BPV differs between females and males in the ICU and whether sex modifies the association between BPV and clinical outcomes.

This retrospective study included all adult patients admitted to the ICU between January 2013 and December 2023. Exposure was the biologically-assigned sex. Main outcomes were BPV measured by normalised average real variability (ARV) and coefficient of variation during the first 7 days of ICU admission. Exploratory outcomes included ICU mortality. Multivariable regression models were used to adjust for patient characteristics.

A total of 11 153 admissions were included, of which 4390 (39.4%) were females. Females had increased variability in mean arterial pressure (MAP) and diastolic blood pressure (DBP) compared with males (normalised ARV of MAP: 8.2% vs 8.2%, adjusted coefficient 0.15, 95% CI 0.03 to 0.26 and normalised ARV of DBP: 9.3% vs 9.1%, adjusted coefficient 0.41, 95% CI 0.27 to 0.55). In the separate multivariable logistic regression analysis, BPV was associated with increased ICU mortality in a dose dependent manner (p<0.001). Each percentage increase in MAP variability was associated with 12% higher odds of ICU mortality, an effect that was modified by sex (p for interaction=0.024).

Females have higher variability in MAP and DBP compared to males during critical illness, which results in association with higher risks of short-term mortality. A thorough understanding of physiological differences, risk stratification and potential treatment strategies are crucial for mitigating sex-related disparities in the ICU.