Objective: To conduct a substudy of POISE-3 to determine whether a perioperative hypotension-avoidance strategy reduces the risk of acute kidney injury compared with a hypertension-avoidance strategy.

Design: Randomized clinical trial with 1:1 randomization to the intervention (a perioperative hypotension-avoidance strategy) or control (a hypertension-avoidance strategy).

Intervention: If the presurgery systolic blood pressure (SBP) is <130 mmHg, all antihypertensive medications are withheld on the morning of surgery. If the SBP is ≥130 mmHg, some medications (but not angiotensin receptor blockers [ACEIs], angiotensin receptor blockers [ARBs], or renin inhibitors) may be continued in a stepwise manner. During surgery, the patients' mean arterial pressure (MAP) is maintained at ≥80 mmHg. During the first 48 hours after surgery, some antihypertensive medications (but not ACEIs, ARBs, or renin inhibitors) may be restarted in a stepwise manner if the SBP is ≥130 mmHg.

Control: Patients receive their usual antihypertensive medications before and after surgery. The patients' MAP is maintained at ≥60 mmHg from anesthetic induction until the end of surgery.

Setting: Recruitment from 108 centers in 22 countries from 2018 to 2021.

Patients: Patients (~6800) aged ≥45 years having noncardiac surgery who have or are at risk of atherosclerotic disease and who routinely take antihypertensive medications.

Measurements: The primary outcome of the substudy is postoperative acute kidney injury, defined as an increase in serum creatinine concentration of either ≥26.5 μmol/L (≥0.3 mg/dL) within 48 hours of randomization or ≥50% within 7 days of randomization.

Methods: The primary analysis (intention-to-treat) will examine the relative risk and 95% confidence interval of acute kidney injury in the intervention versus control group. We will repeat the primary analysis using alternative definitions of acute kidney injury and examine effect modification by preexisting chronic kidney disease, defined as a prerandomization estimated glomerular filtration rate <60 mL/min/1.73 m2.

Results: Substudy results will be analyzed in 2022.

Limitations: It is not possible to mask patients or providers to the intervention; however, objective measures will be used to assess acute kidney injury.

METHODS: The PeriOperative Ischemic Evaluation (POISE)-3 Trial is a large international randomized controlled trial designed to determine if TXA is superior to placebo for the composite outcome of life-threatening, major, and critical organ bleeding, and non-inferior to placebo for the occurrence of major arterial and venous thrombotic events, at 30 days after randomization. Using a partial factorial design, POISE-3 will additionally determine the effect of a hypotension-avoidance strategy versus a hypertension-avoidance strategy on the risk of major cardiovascular events, at 30 days after randomization. The target sample size is 10,000 participants. Patients ≥45 years of age undergoing noncardiac surgery, with or at risk of cardiovascular and bleeding complications, are randomized to receive a TXA 1 g intravenous bolus or matching placebo at the start and at the end of surgery. Patients, health care providers, data collectors, outcome adjudicators, and investigators are blinded to the treatment allocation. Patients on ≥ 1 chronic antihypertensive medication are also randomized to either of the two blood pressure management strategies, which differ in the management of patient antihypertensive medications on the morning of surgery and on the first 2 days after surgery, and in the target mean arterial pressure during surgery. Outcome adjudicators are blinded to the blood pressure treatment allocation. Patients are followed up at 30 days and 1 year after randomization.

DISCUSSION: Bleeding and hypotension in noncardiac surgery are common and have a substantial impact on patient prognosis. The POISE-3 trial will evaluate two interventions to determine their impact on bleeding, cardiovascular complications, and mortality.