Association of Blood Pressure Variability With Death and Discharge Destination Among Critically Ill Patients With and Without Stroke

Abstract

Background and objectives: It is unclear whether blood pressure variability's (BPV) association with worse outcomes is unique to patients with stroke or a risk factor among all critically ill patients. We (1) determined whether BPV differed between patients with stroke and nonstroke patients, (2) examined BPV's associations with in-hospital death and favorable discharge destination in patients with stroke and nonstroke patients, and (3) assessed how minimum mean arterial pressure (MAP)-a correlate of illness severity and cerebral perfusion-affects these associations.

Methods: This is a retrospective analysis of adult intensive care unit patients hospitalized between 2001 and 2012 from the Medical Information Mart for Intensive Care III database. Confounder-adjusted logistic regressions determined associations between BPV, measured as SD and average real variability (ARV), and (1) in-hospital death and (2) favorable discharge, with testing of minimum MAP for effect modification.

Results: BPV was higher in patients with stroke (N = 2,248) compared with nonstroke patients (N = 9,085) (SD mean difference 2.3, 95% CI 2.1-2.6, p < 0.01). After adjusting for minimum tertile of MAP and other confounders, higher SD remained significantly associated (p < 0.05) with higher odds of in-hospital death for patients with acute ischemic strokes (AISs, odds ratio [OR] 2.7, 95% CI 1.5-4.8), intracerebral hemorrhage (ICH, OR 2.6, 95% CI 1.6-4.3), subarachnoid hemorrhage (SAH, OR 3.4, 95% CI 1.2-9.3), and pneumonia (OR 1.9, 95% CI 1.1-3.3) and lower odds of favorable discharge destination in patients with ischemic stroke (OR 0.3, 95% CI 0.2-0.6) and ICH (OR 0.4, 95% CI 0.3-0.6). No interaction was found between minimum MAP tertile with SD (p > 0.05). Higher ARV was not significantly associated with increased risk of death in any condition when adjusting for illness severity but portended worse discharge destination in those with AIS (OR favorable discharge 0.4, 95% CI 0.3-0.7), ICH (OR favorable discharge 0.5, 95% CI 0.3-0.7), sepsis (OR favorable discharge 0.8, 95% CI 0.6-1.0), and pneumonia (OR favorable discharge 0.5, 95% CI 0.4-0.8).

Discussion: BPV is higher and generally associated with worse outcomes among patients with stroke compared with nonstroke patients. BPV in patients with AIS and patients with ICH may be a marker of central autonomic network injury, although clinician-driven blood pressure goals likely contribute to the association between BPV and outcomes.