The association between atherosclerotic renal artery stenosis and acute kidney injury in patients undergoing cardiac surgery

Explainable Boosting Machine approach identifies risk factors for acute renal failure

BACKGROUND

Risk stratification and outcome prediction are crucial for intensive care resource planning. In addressing the large data sets of intensive care unit (ICU) patients, we employed the Explainable Boosting Machine (EBM), a novel machine learning model, to identify determinants of acute kidney injury (AKI) in these patients. AKI significantly impacts outcomes in the critically ill.

METHODS

An analysis of 3572 ICU patients was conducted. Variables such as average central venous pressure (CVP), mean arterial pressure (MAP), age, gender, and comorbidities were examined. This analysis combined traditional statistical methods with the EBM to gain a detailed understanding of AKI risk factors.

RESULTS

Our analysis revealed chronic kidney disease, heart failure, arrhythmias, liver disease, and anemia as significant comorbidities influencing AKI risk, with liver disease and anemia being particularly impactful. Surgical factors were also key; lower GI surgery heightened AKI risk, while neurosurgery was associated with a reduced risk. EBM identified four crucial variables affecting AKI prediction: anemia, liver disease, and average CVP increased AKI risk, whereas neurosurgery decreased it. Age was a progressive risk factor, with risk escalating after the age of 50 years. Hemodynamic instability, marked by a MAP below 65 mmHg, was strongly linked to AKI, showcasing a threshold effect at 60 mmHg. Intriguingly, average CVP was a significant predictor, with a critical threshold at 10.7 mmHg.

CONCLUSION

Using an Explainable Boosting Machine enhance the precision in AKI risk factors in ICU patients, providing a more nuanced understanding of known AKI risks. This approach allows for refined predictive modeling of AKI, effectively overcoming the limitations of traditional statistical models.

Bilateral renal artery stenosis impacts postoperative complications after major vascular surgery

Background

Incidental atherosclerotic renal artery stenosis (RAS) is common in patients undergoing vascular surgery and has been shown to be associated with postoperative AKI among patients undergoing major non-vascular surgeries. We hypothesized that patients with RAS undergoing major vascular procedures would have a higher incidence of AKI and postoperative complications than those without RAS.

Methods

A single-center retrospective cohort study of 200 patients who underwent elective open aortic or visceral bypass surgery (100 with postoperative AKI; 100 without AKI) were identified. RAS was then evaluated by review of pre-surgery CTAs with readers blinded to AKI status. RAS was defined as ≥50 % stenosis. Univariate and multivariable logistic regression was used to assess association of unilateral and bilateral RAS with postoperative outcomes.

Results

17.4 % (n = 28) of patients had unilateral RAS while 6.2 % (n = 10) of patients had bilateral RAS. Patients with bilateral RAS had similar preadmission creatinine and GFR as compared to unilateral RAS or no RAS. 100 % (n = 10) of patients with bilateral RAS had postoperative AKI compared with 45 % (n = 68) of patients with unilateral or no RAS (p < 0.05). In adjusted logistic regression models, bilateral RAS predicted severe AKI (OR 5.82; CI 1.33, 25.53; p = 0.02), in-hospital mortality (OR 5.71; CI 1.03, 31.53; p = 0.05), 30-day mortality (OR 10.56; CI 2.03, 54.05; p = 0.005) and 90-day mortality (OR 6.88; CI 1.40, 33.87; p = 0.02).

Conclusions

Bilateral RAS is associated with increased incidence of AKI as well as in-hospital, 30-day, and 90-day mortality suggesting it is a marker of poor outcomes and should be considered in preoperative risk stratification.

Postoperative Acute Kidney Injury in Williams Syndrome Compared With Matched Controls

OBJECTIVES

Cardiovascular manifestations occur in over 80% of Williams syndrome (WS) patients and are the leading cause of morbidity and mortality. One-third of patients require cardiovascular surgery. Renal artery stenosis (RAS) is common in WS. No studies have assessed postoperative cardiac surgery-related acute kidney injury (CS-AKI) in WS. Our objectives were to assess if WS patients have higher risk of CS-AKI postoperatively than matched controls and if RAS could contribute to CS-AKI.

DESIGN

This was a retrospective study of all patients with WS who underwent cardiac surgery at our center from 2010 to 2020. The WS study cohort was compared with a group of controls matched for age, sex, weight, and surgical procedure.

SETTING

Patients underwent cardiac surgery and postoperative care at Lucile Packard Children's Hospital Stanford.

PATIENTS

There were 27 WS patients and 43 controls (31% vs 42% female; p = 0.36). Median age was 1.8 years (interquartile range [IQR], 0.7-3.8 yr) for WS and 1.7 years (IQR, 0.8-3.1 yr) for controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Postoperative hemodynamics, vasopressor, total volume input, diuretic administration, and urine output were collected in the first 72 hours. Laboratory studies were collected at 8-hour intervals. Multivariable analysis identified predictors of CS-AKI.Controlled for renal perfusion pressure (RPP) and vasoactive inotrope score (VIS), compared with controls, the odds ratio (OR) of CS-AKI in WS was 4.2 (95% CI, 1.1-16; p = 0.034). Higher RPP at postoperative hours 9-16 was associated with decreased OR of CS-AKI (0.88 [0.8-0.96]; p = 0.004). Increased VIS at hour 6 was associated with an increased OR of CS-AKI (1.47 [1.14-1.9]; p = 0.003). Younger age was associated with an increased OR of CS-AKI (1.9 [1.13-3.17]; p = 0.015).

CONCLUSIONS

The OR of CS-AKI is increased in pediatric patients with WS compared with controls. CS-AKI was associated with VIS at the sixth postoperative hour. Increases in RPP and mean arterial pressure were associated with decreased odds of CS-AKI.

New Insights into Acute-on-Chronic Kidney Disease in Nephrology Patients: The CKD-REIN Study

BACKGROUND

Acute-on-chronic kidney disease (ACKD) is poorly understood and often overlooked. We studied its incidence, circumstances, determinants, and outcomes in patients with CKD.

METHODS

We used the Kidney Disease Improving Global Outcomes criteria to identify all-stage acute kidney injury (AKI) events in 3033 nephrology outpatients with CKD stage 3-5 participating in the CKD-REIN cohort study (2013-2020), and cause-specific Cox models to estimate hazard ratios (HR, 95% confidence intervals [CI]) of AKI-associated risk factors.

RESULTS

At baseline, 22% of the patients (mean age 67 years, 65% men, mean eGFR 32 ml/min/1.73m2) had a history of AKI. Over a 3-year follow-up, 443 had at least one AKI event: 27% were stage 2 or 3, and 11% required dialysis; 74% involved hospitalization including 47% acquired as hospital inpatients; a third were not reported in hospital discharge reports. Incidence rates were 10.1 and 4.8 per 100 person-years in patients with and without an AKI history, respectively. In 2375 patients without this history, male sex, diabetes, cardiovascular disease, cirrhosis, several drugs, low eGFR, and serum albumin levels were significantly associated with a higher risk of AKI, as were low birth weight (<2500 g) (adjusted HR, 1.98; 95%CI, 1.35 to 2.91) and hemoglobin level (HR 1.21; 1.12 to 1.32 per 1 g/dl decrease). Within one year, only 63% of the patients had recovered their previous kidney function, 13.7% had started kidney replacement therapy, and 12.7% had died.

CONCLUSIONS

The study highlights the high rate of hospital-acquired AKI events in patients with CKD, and their underreporting at hospital discharge. It also reveals low birth weight and anemia as possible new risk factors in CKD patients.

Risk Factors for Acute Kidney Injury after Cardiovascular Surgery: Evidence from 2,157 Cases and 49,777 Controls - A Meta-Analysis

PURPOSE

Cardiovascular surgery-associated acute kidney injury (AKI-CS) contributes to mortality and morbidity. However, risk factors accelerating its development are unclear. We identified risk factors for AKI-CS in patients with cardiopulmonary bypass in the hospital surgical intensive care unit to predict and minimize renal complication in future cardiac surgery.

METHODS

We analyzed data from 14 case-control studies published prior to June 2014 and indexed in Science Citation Index, PubMed, and other databases to determine the major risk factors for AKI-CS.

RESULTS

Analyzed risk factors were divided into three groups: preoperative, intraoperative and postoperative. Preoperative factors included: age (OR, 4.87; 95% CI, 3.50-6.24), NYHA class III/IV (OR, 2.53; 95% CI, 1.32-4.86), hypertension (OR, 1.68; 95% CI, 1.44-1.97), preoperative creatinine (OR, 0.66; 95% CI, 0.18-1.14), peripheral vascular disease (OR, 1.31 95% CI, 1.09-1.57), respiratory system disease (OR, 1.29; 95% CI, 1.10-1.50), diabetes mellitus (OR, 1.52; 95% CI, 1.07-2.16), and cerebrovascular disease (OR, 2.13; 95% CI, 1.11-4.09). Intraoperative factors were: cardiopulmonary bypass time (OR, 33.78; 95% CI, 23.15-44.41), aortic clamping time (OR, 13.24; 95% CI, 7.78-18.69), use of intra-aortic balloon pump (OR, 4.44; 95% CI, 2.37-8.30), and type of surgery (OR, 1.01; 95% CI, 0.43-2.39). Postoperative factors were: infection (OR, 3.58; 95% CI, 1.43-8.97), redo operation (OR, 2.57; 95% CI, 1.75-3.78), emergency surgery (OR, 4.76; 95% CI, 3.05-7.43), and low cardiac output (OR, 2.30; 95% CI, 1.05-5.04).

CONCLUSIONS

Our results support that preoperative, intraoperative, and postoperative factors are associated with AKI-CS. Ejection fraction, BMI, acute myocardial infarction, type of surgery, and congestive heart failure were not absolutely associated with AKI.