In this single-center, retrospective observational study, we included adult patients (age ≥ 18 years old) with no significant physical function problems (performance status ≤ 2) who had received planned preoperative chemotherapy including cisplatin and underwent transthoracic esophagectomy for esophageal cancer under general anesthesia between January 2017 and February 2022 at Nagoya City University Hospital. Patients who had underwent mediastinoscopic surgery, and colon reconstruction were excluded, as different surgical invasiveness could impact postoperative complications. We also excluded those with missing values including serum albumin, urinary protein, estimated glomerular filtration rate (eGFR), hemoglobin, and C-reactive protein (CRP) levels. The observation period ended when the patient was discharged from the hospital after surgery.
The study protocol was approved by the institutional review board at Nagoya City University Hospital (NO. 60-18-0008), and informed consent was approved by institutional review board (Nagoya City University Graduate School of Medical Sciences and Nagoya City University Hospital Institutional Review Board) due to the retrospective nature of the study.
Definitions
c-AKI was defined as stage 2 or higher AKI after preoperative chemotherapy within 10 days after chemotherapy using the KDIGO criteria (increase in serum creatinine to 2.0-2.9 times baseline, or reduction in urine output to < 0.5 mL/kg/h for ≥ 12 hours) [14]. All patients were hospitalized for preoperative chemotherapy, and during hospitalization, urine output was measured every 6 hours. When daily urine output was < 1500 mL or weight gain was more than 3 kg after chemotherapy, 20 mg furosemide was administered intravenously.
Anastomotic leakage was defined by imaging extraintestinal leakage on CT and fluoroscopy. Postoperative pneumonia was defined by the Uniform Pneumonia Score (van der Sluis et al. [15]) determined by body temperature, leucocyte count, and pulmonary radiographic findings. SSI was defined according to the guidelines of the Centers for Disease Control and Prevention [16].
Cancer staging was defined by the Japanese Classification of Esophageal Cancer, 11th Edition [17, 18]. Prechemotherapy and preoperative laboratory data were defined as those within 10 days before chemotherapy or surgery, and the closest to the date of chemotherapy or surgery, respectively. eGFR was calculated using the equation developed for the Japanese population by the Japanese Society of Nephrology [19].
Statistical analyses
Data were presented as numbers (%) or medians (interquartile range). Demographic information for those with and without c-AKI was compared by Fisher’s exact test, the Man-Whitney U test, or Wilcoxon signed-rank test. The length of hospital stay was compared between patients with and without c-AKI using Kaplan-Meier curves and log-rank tests. The trajectories of postoperative weight change, CRP levels, and eGFR were analyzed using a mixed-effects model, with time-dependent weight change, CRP, and eGFR levels as dependent variables and an interaction term between the cubic term of time and c-AKI as the independent variable. We included data up to the time before the event of interest or 20 postoperative days.
The associations between c-AKI and postoperative complications (anastomotic leakage, postoperative pneumonia, and SSI) were analyzed using logistic regression models. The data were adjusted for the logic of the propensity score (PS) for c-AKI. The PS was derived from models including age, sex, body mass index, eGFR, hemoglobin, CRP, albumin, urinary protein, Brinkman Index, height-adjusted total kidney volume measured on CT, type of neoadjuvant chemotherapy, pharyngo-laryngoesophagectomy, comorbidies, and medications as listed in Table 1. Sensitivity analyses were performed with inverse probability weighting (IPW). Data with IPW values at less than the 5th percentile or more than the 95th percentile were excluded from the analyses.
Table 1
| Without c-AKI n = 79 | With c-AKI n = 22 | P-value |
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Age | 72.0 (38.0–82.0) | 70.5 (55.0–79.0) | 0.70 |
Male sex | 62 (78.8) | 21 (95.8) | 0.11 |
Body mass index (kg/m2) | 20.3 (15.1–29.3) | 20.2 (17.0–29.0) | 0.64 |
eGFR (mL/min/1.73m2) | 74.7 (42.0–112.3) | 72.1 (38.2–119.9) | 0.87 |
Performance Status 0 1 2 | 69 (87.3) 8 (10.1) 2 (2.5) | 19 (86.3) 3 (13.6) 0 (0) | 0.82 |
Hemoglobin (g/dL) | 13.3 (9.3–17.2) | 13.9 (10.9–15.8) | 0.16 |
C-reactive protein (mg/dL) | 0.14 (0.03– 6.77) | 0.20 (0.03–2.88) | 0.86 |
Albumin (g/dL) | 3.9 (2.7– 4.9) | 3.9 (2.9–4.6) | 0.36 |
Urinary protein (+) or more | 6 (7.6) | 2 (9.1) | 1.00 |
Brinkman Index | 700 (0–85260) | 820 (0–2400) | 0.70 |
HtTKV (mL/m2) | 104.3 (76.4–160.6) | 109.1 (73.5–151.5) | 0.75 |
Preoperative chemotherapy; DCF/FP | 45/34 | 16/6 | 0.22 |
Pharyngo-laryngoesophagectomy | 6 (7.6) | 2 (9.1) | 1.00 |
Stage of esophageal cancer 0 1 2 3 4 | 2 (2.5) 7 (8.9) 25 (31.6) 37 (46.8) 8 (10.1) | 0 (0) 2 (9.1) 6 (27.3) 10 (45.5) 4 (18.2) | 0.86 |
History of cerebrovascular accidents | 2 (2.5) | 1 (4.5) | 0.53 |
History of diabetes mellitus | 7 (8.9) | 2 (9.1) | 1.00 |
History of heart failure | 1 (1.3) | 1 (4.5) | 0.39 |
History of hypertension | 35 (44.3) | 8 (36.4) | 0.63 |
ACE inhibitors | 0 (0) | 0 (0) | NA |
Antiplatelet agents | 6 (7.6) | 4 (18.2) | 0.22 |
ARBs | 21 (26.6) | 6 (27.3) | 1.00 |
Diuretics | 1 (1.3) | 0 (0) | 1.00 |
Insulin | 0 (0) | 0 (0) | NA |
NSAIDs | 0 (0) | 0 (0) | NA |
SGLT2 inhibitors | 1 (1.3) | 0 (0) | 1.00 |
Other anti-diabetic medications | 5 (6.3) | 2 (9.1) | 0.64 |
Statins | 5 (6.3) | 4 (18.2) | 0.10 |
Data were shown as number (%) or median (interquartile range) as appropriate. |
p-values were calculated by Fisher’s exact test or Mann–Whitney U test. |
c-AKI: cisplatin-induced acute kidney injury eGFR: estimated glomerular filtration rate |
HtTKV: height-adjusted total kidney volume (total kidney volume divided by height square) |
DCF: Docetaxel + Cisplatin + 5 fluorouracil |
FP: Cisplatin + 5 fluorouracil |
ACE: angiotensin-converting enzymes |
ARB: angiotensin receptor blockers |
NSAIDs: non-steroidal anti-inflammatory drugs |
SGLT2: sodium-glucose cotransporters 2 |
Mediation percentage was defined as;
Mediation percentage =[100*(OR1-OR2)]/(OR-1)
OR1: odds ratio of c-AKI for anastomotic leakage (data adjusted for the logit of PS)
OR2: odds ratio of c-AKI for anastomotic leakage (data adjusted for the logit of PS and covariates of interest).
A 1000 bootstrap resampling procedure was used to estimate the 95% confidence intervals (95%CI).
P-values < 0.05 were considered statistically significant. Statistical analyses were performed using STATA MP v.17.1 (Stata Corp., College Station, TX).