Admission blood pressure and blood pressure variability in medical emergency predicts 3-month mortality and readmission

Background The admission systolic blood pressure (SBP) recorded at the emergency department is typically elevated and tends to decrease, while various degrees of blood pressure variability (BPV) remain. Whether admission SBP or mean SBP and BPV from resting beat-to-beat measurements are better associated with short term outcome remains unknown. Methods We conducted a prospective study, including adults acutely admitted to the emergency department at a larger Danish tertiary care Hospital in Denmark from 2019 to 2023. We measured blood pressure (BP) at admission and beat-to-beat BP and BPV during 10-minute rest. We defined BPV as the standard deviation from the mean of the beat-to-beat SBP measurements. Primary outcome was defined as 3-month all-cause mortality or readmission, and secondary outcome as 3-month cardiovascular mortality or readmission for cardiovascular disease. Results Among 951 patients included, mean age was 64 (Standard deviation; 17) with 44% female. During 3-month follow-up, 284 (30%) patients met a primary outcome and 69 (7,2%) a secondary outcome. In Cox models adjusted for relevant comorbidities, admission SBP, but neither mean SBP or BPV, was significantly associated with primary outcome (Hazard ratio (HR) 0.971, 95% confidence interval (CI) 0.948-0.995, p=0.017) for each 5 mmHg increase in SBP. When exploring both extremes of upper and lower quartiles, BPV >10 mmHg was associated with increased cardiovascular events (HR 2.019, 95% CI 1.142-3.569, p=0.016) in the adjusted Cox model. Conclusion In this study, low admission SBP was associated with all-cause readmissions and death, while BPV above 10 mmHg was associated with 3-month risk of cardiovascular events.