# Preoperative serum creatinine changes and acute kidney injury in patients underwent cardiac surgery

## TL;DR

This study found that drops in pre-surgery kidney function markers are linked to worse outcomes after heart surgery, even if kidney injury occurs.

## Contribution

Identifies negative preoperative serum creatinine changes as a risk factor for poor outcomes in cardiac surgery patients with AKI.

## Key findings

- Negative preoperative serum creatinine changes are associated with increased odds of acute kidney injury.
- Negative changes in serum creatinine correlate with higher in-hospital mortality and longer ICU stays in AKI patients.
- Elevated serum creatinine changes show no significant associations with adverse outcomes.

## Abstract

Preoperative serum creatinine fluctuations are common in open-heart surgery, and their association with postoperative acute kidney injury (AKI) and the combined impact on patient outcomes warrant further investigation.

This retrospective cohort study assessed patients undergoing open-heart surgery. Preoperative serum creatinine changes (ΔScr) were calculated as the difference between the serum creatinine value within 48 h before surgery and baseline. Patients were categorized into three groups based on ΔScr: negative (< 0 mg/dl), normal (0–0.3 mg/dl), and elevated (≥0.3 mg/dl). Multivariable logistic regression and restricted cubic spline models were used to analyze the clinical outcomes.

Of the 560 patients included, 40.2% developed AKI. There were significant increases in the odds of AKI [adjusted odds ratio (AOR), 1.51; 95% CI, 1.32–1.72, per 0.1 mg/dl increase], severe AKI (AOR, 1.45; 95% CI, 1.24–1.70), and AKI non-recovery (AOR, 1.37; 95% CI, 1.19–1.59). In AKI patients, negative ΔScr was associated with a higher rate of in-hospital mortality and ICU LOS >72 h compared to without AKI, while elevated ΔScr showed no significant differences. In addition, negative ΔScr was associated with a higher risk of in-hospital mortality (AOR, 4.50; 95% CI, 1.00–20.15) and ICU LOS >72 hours (AOR, 2.81; 95% CI, 1.13–6.96) compared with normal ΔScr. No significant associations were observed with elevated ΔScr. In contrast, among patients without AKI, neither negative nor elevated ΔScr were associated with in-hospital mortality or prolonged ICU LOS.

In this retrospective study of elective cardiac surgery, negative changes in preoperative serum creatinine were less likely to development of AKI. However, patients with negative changes who developed postoperative AKI had a higher risk of in-hospital mortality and prolonged ICU stays. No significant associations with these outcomes were observed with elevated changes.