Blood pressure (BP) is an important target for kidney injury, but few data showed optimal BP in patients with acute kidney injury (AKI) relative to mortality.Design and Method:
We performed a retrospective cohort study of 2304 patients who had their creatinine levels measured (≥ 1 measurement) during admission for a period of 1 year (January 1, 2013 through December 31, 2013) at tertiary hospital and were diagnosed with AKI by Kidney Disease Improving Global Outcomes (KDIGO) definition based on serum creatinine criteria. Average BP (systolic [SBP] and diastolic [DBP]) was categorized into 10-mmHg increments (at early period of admission within 48hr and at 48hr after development of AKI).Results:
The overall 90-day and 1-year mortality for patients were 17.6 % (405/2304) and 29.0% (669/2304). The relationship between BP (SBP and DBP) followed a J-shaped curve association with increased 90-day and 1-year mortality at low BP value in univariable analysis (SBP <120 mmHg and DBP <60 mmHg at admission and after AKI) (Figure1). However, SBP at 48hr after AKI was only a predictor for 90-day mortality after adjustment for baseline variables (reference systolic BP ≥ 140 mmHg, <100 mmHg, Hazard ratio [HR] 4.528, P <0.001; 100–110 mmHg, HR 2.177, P = 0.005; 110–120 mmHg, HR 1.764, P = 0.033; 120–130 mmHg, HR 1.415, P = 0.215; 130–140 mmHg, HR 1.656, P = 0.088). This trend also remained in the relationship between average SBP after AKI and 1-year mortality.Conclusions:
After AKI, a J-shaped curve association existed between SBP at 48hr after AKI and 90-day/1-year mortality, which suggests that too low of a pressure (especially <120 mmHg) may be dangerous. SBP after AKI was only a predictor for mortality rather than SBP/DBP at admission or DBP after AKI.