The association between systolic blood pressure and in-hospital mortality in older emergency department patients who are hospitalised with a suspected infection.

Objective: In existing risk stratification and resuscitation guidelines for sepsis, a hypotension threshold of systolic blood pressure (SBP) below 90-100 mmHg is typically used. However, for older patients, the clinical relevance of a SBP in a seemingly 'normal' range (>100 mmHg) is still poorly understood, as they may need higher SBP for adequate tissue perfusion due to arterial stiffening. We therefore investigated the association between SBP and mortality in older emergency department (ED) patients hospitalised with a suspected infection.

Methods: In this observational multicentre study in the Netherlands, we interrogated an existing prospective database of consecutive ED patients hospitalised with a suspected infection between 2011 and 2016. We investigated the association between SBP categories (≤100, 101-120, 121-139, ≥140 mmHg) and in-hospital mortality in patients of 70 years and older. We adjusted for demographics, comorbidity, disease severity and admission to ward/intensive care using multivariable logistic regression.

Results: In the 833 included older patients, unadjusted in-hospital mortality increased from 4.7% (n=359) in SBP ≥140 mmHg to 20.8% (n=96) in SBP ≤100 mmHg. SBP categories were linearly associated with case-mix-adjusted in-hospital mortality. The adjusted ORs (95% CI) for ≤100, 101-120 and 121-139 mmHgcompared with the reference of ≥140 mmHg were 3.8 (1.8 to 7.8), 2.8 (1.4 to 5.5) and 1.9 (0.9 to 3.7), respectively.

Conclusion: In older ED patients hospitalised with a suspected infection, we found an inverse linear association between SBP and case-mix-adjusted in-hospital mortality. Our data suggest that the commonly used threshold for hypotension is not clinically meaningful for risk stratification of older ED patients with a suspected infection.