# Defining Subclinical Acute Kidney Injury Within 72 Hours After Minimally Invasive Esophagectomy in Prone Position and Its Association With Outcomes: An Exploratory Study

## TL;DR

This study explores how small increases in kidney function markers after a specific surgery are linked to worse outcomes, even when they don't meet official kidney injury criteria.

## Contribution

Identifies subclinical acute kidney injury as a risk factor for poor outcomes after prone-position minimally invasive esophagectomy.

## Key findings

- Subclinical AKI occurred in 1.3% of patients after MIE.
- Patients with subclinical AKI had higher rates of prolonged hospital stay and mechanical ventilation.
- Subclinical AKI and AKI groups had similar outcomes, but both were worse than the reference group.

## Abstract

Introduction: This study aimed to investigate the effects of slight increases in the serum creatinine concentration (sCr) postoperatively that do not meet the diagnostic criteria for acute kidney injury (AKI) on outcomes in patients undergoing minimally invasive esophagectomy (MIE) in the prone position.

Methods: A retrospective cohort study was carried out on patients who underwent MIE between January 2010 and December 2024. Patients who underwent MIE were categorized into three groups: those diagnosed with AKI based on the Kidney Disease: Improving Global Outcomes creatinine criteria within 72 hours after surgery (AKI group); those with a postoperative percentage increase in serum creatinine (ΔsCr%) of 30% or more compared with baseline (subclinical AKI group); and those with a ΔsCr% <30% (reference group). Patient outcomes were compared among the groups.

Results: Of 933 patients, 33, 12, and 888 patients were classified into the AKI, subclinical AKI, and reference groups, respectively. The proportion of patients with postoperative hospital stay ≥25 days and the proportion of patients who required mechanical ventilation after surgery were significantly higher in the AKI group (51.5%, 27.3%) and the subclinical AKI group (50.0%, 25.0%) than in the reference group (18.6%, 3.3%) (p<0.0167, Bonferroni correction). No statistically significant differences were identified between the AKI and subclinical AKI groups with respect to these outcomes.

Conclusions: The incidence of subclinical AKI, defined based on ΔsCr% after MIE, was 1.3%. Subclinical AKI patients were significantly more likely to require postoperative mechanical ventilation. To prevent worsening outcomes after MIE, not only AKI, but also subclinical AKI should be targeted for prevention.