Blood Pressure Control and Mortality After AKI

Approximately 20% to 25% of hospital admissions are complicated by acute kidney injury (AKI) events. AKI-related events are associated with increased rates of long-term mortality. Effective blood pressure control following AKI may have beneficial effects on outcomes, but there are few data available on appropriate blood pressure targets and the optimal timing of initiation of blood pressure-lowering medication.

Benjamin R. Griffin and colleagues at the University of Iowa Hospital & Clinics, Iowa City, conducted a retrospective cohort analysis of data on US veterans with in-hospital AKI. Results of the analysis were reported during a poster session at the American Society of Nephrology Kidney Week 2023. The poster was titled Time to Blood Pressure Control and Blood Pressure Targets Significantly Impact Mortality Among Veterans Following AKI.

The cohort included veterans admitted to the hospital from 2013 to 2018 who experienced an in-hospital AKI event. Eligible patients had one or more blood pressure measurement within 30 days of hospital discharge. Systolic blood pressure was treated as time dependent and categorized as <120, 120-129, and 130-139 mm Hg, relative to >140 mm Hg.

The primary outcome of interest was time to death. Cox proportional hazards regression models were adjusted for demographics, chronic lung disease, unexplained weight loss, dementia, congestive heart failure, hematocrit, blood urea nitrogen, bilirubin, and albumin. Hazard ratios (HRs) were calculated at seven different time points to evaluate the impact of blood pressure control over time (30, 60, 120, 180, 270, and 365 days after discharge).

The cohort included 97,376 veterans. Of those, 15% (n=14,819) died within 1 year of hospital discharge. Rates of hypertension, congestive heart failure, and diabetes were high in the overall cohort (85%, 28%, and 19%, respectively). Relative to uncontrolled blood pressure, HRs for mortality were significantly reduced for all blood pressure categories <140 mm Hg. The lowest HRs were in the group with blood pressure 130-139 mm Hg. Relative to uncontrolled blood pressure, HRs were lowest at the 30-day mark for all blood pressure categories and increased over time.

In summary, the authors said, “Among post-AKI veterans, blood pressure control within 30 days of discharge was associated with reduced mortality, but this benefit was attenuated over time. All blood pressure targets were superior to blood pressure >140 mm Hg, but the 130-139 mm Hg group had the lowest risk of death at each time point. These findings highlight the importance of achieving blood pressure control promptly post-AKI and suggest that targeting a systolic blood pressure of 130-139 is ideal.”

Source: Griffin BR, Sarrazin MV, Masaaki Y, et al. Time to blood pressure control and blood pressure targets significantly impact mortality among veterans following AKI. FR-PO105. Abstract of a poster presented at the American Society of Nephrology Kidney Week 2023; November 3, 2023; Philadelphia, Pennsylvania.