U-Shaped Relationship Between Preoperative Serum Magnesium and Postoperative Acute Kidney Injury in Elderly Patients Undergoing Non-Cardiac Surgery: A Retrospective Cohort Study.

ObjectiveTo investigate the risk factors and prognosis of acute kidney injury (AKI) in elderly patients after surgery based on the Medical Information Mart for Intensive Care IV (MIMIC-IV).MethodsA retrospective analysis was conducted using MIMIC-IV data pertaining to aged postoperative patients. By logistic regression analysis models, Kaplan–Meier survival curve and Cox proportional hazards regression model. To evaluate the independent risk variables and prognosis of postoperative AKI in elderly patients.ResultsA total of 1784 elderly patients who met the inclusion criteria were analyzed. Among them, 1423 developed AKI after surgery. The development of AKI was significantly associated with the use of vasoactive drugs, invasive mechanical ventilation, traumatic surgical procedures, and elevated serum creatinine (Scr) levels within 24 h of admission. Cardiac surgery was also highly correlated with postoperative AKI. Factors associated with 28-day mortality in elderly patients with AKI included age ≥ 75 years, higher Sequential Organ Failure Assessment (SOFA) scores, elevated blood urea nitrogen (BUN) levels, presence of cerebrovascular disease (CVD), invasive ventilation, neurosurgical procedures, and traumatic surgical procedures.ConclusionsAge, Gender, Intervention measures and laboratory indicators can affect the incidence and prognosis of elderly patients’ postoperative AKI. Early identification and timely intervention in patients with these high-risk factors are of practical significance in preventing the occurrence and progression of AKI.

Perioperative Acute Kidney Injury

The risk of developing perioperative acute kidney injury (AKI) in elderly patients increases with age. The combined involvement of aging kidneys, coexisting multiple underlying chronic diseases, and increased exposure to potential renal stressors and nephrotoxic drugs or invasive procedures constitute susceptibility factors for AKI in elderly patients. The perioperative AKI in elderly patients undergoing noncardiac surgery has its own specific population characteristics, so it is necessary to further explore the characteristics of AKI in elderly patients in terms of epidemiology, clinical diagnosis, risk factors, and preventive and curative measures to provide meaningful clinical advice to improve prognosis, accelerate recovery, and reduce medical burden in elderly patients. Since AKI has the fastest-growing incidence in older patients and is associated with a worse prognosis, early detection, early diagnosis, and prevention of AKI are important for elderly patients in the perioperative period. Large, multicenter, randomized controlled clinical studies in elderly non-cardiac surgery patients with AKI can be conducted in the future, with the aim of providing the evidence to reduce of the incidence of AKI and to improve the prognosis of patients.

The Simple Postoperative AKI Risk (SPARK) index is a novel model for predicting risk of postoperative acute kidney injury (PO-AKI) among patients after noncardiac surgery. However, the performance of the index has been inconsistent partly due to heterogeneity in case mix and effects of the involved clinical features. To clarify potential reasons for poor performance, we tested the SPARK index in a cohort of high-risk patients requiring intensive care unit (ICU) care after noncardiac surgery and examined whether model modification by refitting coefficients of clinical features could optimize model performance. This was a single-center prospective cohort study. Preoperative variables of the SPARK index were extracted from electronic medical records. PO-AKI was defined by an increase in sCr ≥26.5 mmol/L within 48 hours or 150% compared with the preoperative baseline value within 7 days after surgery, whereas critical AKI was defined as AKI stage 2 or greater and/or any AKI connected to postoperative death or requiring renal replacement therapy during the hospital stay. Discrimination was evaluated by the area under the receiver operating characteristic curve (AUC), and calibration was evaluated by the Hosmer-Lemeshow χ 2 test and calibration plot. Model modification was performed by rebuilding the model with the original variables of the SPARK index through proportional odds logistic regression among participants in the earlier study period and was validated in the later one. A total of 973 patients were enrolled, among whom 79 (8.1%) PO-AKI cases and 14 (1.4%) critical AKI cases occurred. Our study participants demonstrated a higher SPARK risk score than the SPARK discovery cohort (eg, 8.02% vs 1.20% allocated in the highest risk group), and the incidence of both outcomes increased through the classes of the score (incidence proportion of PO-AKI increased from 2.56% in the lowest risk group to 25.64% in the highest risk group). The AUCs for PO-AKI and critical AKI were 0.703 (95% confidence interval [CI], 0.641-0.765) and 0.699 (95% CI, 0.550-0.848), respectively. The sensitivity, specificity, negative predictive value and positive predictive value were 68.35%, 57.49%, 95.36%, and 12.44%, respectively, when using 10% of predicted probability of PO-AKI as threshold. Calibration plots suggested acceptable consistency between the predicted and actual risk. After model modification, external validation demonstrated a significantly improved AUC for PO-AKI. The SPARK index showed fair discrimination and calibration among patients admitted to the ICU after noncardiac surgery. Modification of the model improved the performance of the model in terms of predicting PO-AKI.

BackgroundHemoglobin-to-red blood cell distribution width ratio (HRR) had great predictive value for the prognosis of malignant tumors and cardiovascular disease. However, its predictive value for the occurrence of acute kidney injury (AKI) in elderly intertrochanteric fracture patients remains unclear. This study aims to analyze the correlation between the early postoperative HRR and the risk of postoperative AKI in elderly intertrochanteric fracture patients.MethodsWe reviewed the medical records of 307 elderly intertrochanteric fracture patients in this single-center retrospective cohort study. We performed univariate analysis on the relevant parameters, and parameters with significant differences were included in the following logistic regression model for multivariate analysis. Then, we used a receiver operating characteristic (ROC) curve to evaluate the predictive value of the early postoperative HRR level for AKI in elderly intertrochanteric fracture patients. Patients were divided into a high HRR group and a low HRR group according to the cutoff point determined by ROC curve analysis. Subsequently, the relevance between postoperative HRR and AKI was further determined using propensity score matching (PSM) and inverse probability of treatment weighting (IPTW).ResultsThe area under the curve of the early postoperative HRR for predicting postoperative AKI was 0.714 (95% CI: 0.618–0.809). The cutoff value was 5.44. The sensitivity was 72.7%, and the specificity was 70.8%. Patients were divided into low HRR (⩽ 5.44) and high HRR (> 5.44) groups according to the cutoff value. PSM and IPTW analysis indicated that the risk of AKI in the low HRR group was significantly higher than that in the high HRR group in both the matched cohort (OR = 6.914, 95% CI: 1.714–46.603, p = 0.016) and the weighted group (OR = 2.784, 95% CI: 1.415–5.811, p = 0.040).ConclusionsEarly postoperative HRR is an accurate, accessible, and economical blood test parameter that can predict the risk of postoperative AKI in elderly patients with femoral intertrochanteric fracture.

To analyze the incidence of acute kidney injury (AKI) in elderly patients with sepsis, compare the clinical characteristics and prognosis between AKI and non-AKI elderly patients with sepsis, and to investigate the impact of classification of AKI and renal replacement therapy (RRT) on the outcome of elderly patients with sepsis. The clinical data of 490 septic patients over 65 years old, admitted to intensive care unit (ICU) of Tianjin First Center Hospital from April 1st, 2016 to December 31st, 2018 were retrospectively analyzed. The patients were divided into two groups according to those with or without AKI. The clinical characteristics of patients were compared, and subgroup analysis of elderly septic patients with AKI was performed according to Kidney Disease: Improving Global Outcomes (KDIGO) staging criteria and whether RRT was performed, to observe the effects of AKI staging and RRT on the prognosis of elderly septic patients with AKI. Multivariate Cox regression analysis was used to screen the risk factors of death in elderly patients with sepsis associated AKI. (1) A total of 490 septic elderly patients were enrolled, including 249 patients with AKI and 241 patients without AKI, with the AKI incidence of 50.8%. Compared with non-AKI group, the patients in AKI group were older (years old: 72.0±7.2 vs. 68.8±5.1), acute physiology and chronic health evaluation II (APACHE II) score and sequential organ failure assessment (SOFA) score were evidently higher (23.1±6.1 vs. 22.0±3.7, 9.4±3.8 vs. 6.1±3.5); the duration of mechanical ventilation [days: 7.0 (5.0, 10.0) vs. 6.0 (3.0, 9.0)], length of ICU stay [days: 12.0 (7.0, 15.0) vs. 7.0 (4.0, 13.0)] and total length of hospital stay [days: 15.0 (10.0, 21.5) vs. 12.0 (7.0, 15.0)] were longer, and ICU mortality and 28-day mortality were evidently higher [22.9% (57/249) vs. 14.1% (34/241), 36.1% (90/249) vs. 24.5% (59/241), all P < 0.05]. (2) According to KDIGO staging, 93 patients were in stage 1, 70 in stage 2 and 86 in stage 3 of AKI. The rate of RRT was increased with increase in KDIGO staging [14.0% (13/93), 30.0% (21/70), 88.4% (76/86)], the duration without mechanical ventilation within 28 days was shortened [days: 20.0 (0, 23.0), 8.0 (0, 20.5), 8.0 (0, 13.0)], the rate of kidney recovery was decreased [71.0% (66/93), 51.4% (36/70), 37.2% (32/86)], meanwhile, the ICU and 28-day mortality was increased [12.9% (12/93), 38.6% (27/70), 20.9% (18/86), and 26.9% (25/93), 35.7% (25/70), 46.5% (40/86), all P < 0.05]. (3) 110 elderly septic patients with AKI were treated with RRT, and 139 without RRT. Compared with non-RRT group, the ratio of mechanical ventilation in RRT group was lowered [46.4% (51/110) vs. 68.3% (95/139)], the duration without mechanical ventilation within 28 days [days: 18.0 (0, 23.0) vs. 10.0 (0, 13.0)], the length of ICU stay [days: 13.0 (12.0, 17.9) vs. 10.0 (6.0, 14.0)] and the total length of hospital stay [days: 22.5 (15.0, 46.0) vs. 16.0 (12.0, 23.0)] were prolonged, and the 28-day mortality was evidently increased [50.0% (55/110) vs. 25.2% (35/139), all P < 0.01], however, no significant difference in ICU mortality was found [27.3% (30/110) vs. 19.4% (27/139), P > 0.05]. (4) Cox regression analysis showed that SOFA score [relative risk (RR) = 1.214, 95% confidence interval (95%CI) = 1.117-1.319], KDIGO stage (RR = 4.077, 95%CI = 1.850-8.982), vasoactive substance usage (RR = 2.896, 95%CI = 1.502-5.584), and mechanical ventilation (RR = 5.787, 95%CI = 1.512-22.156) were the risk factors of 28-day mortality in elderly septic patients with AKI (all P < 0.05). The incidence of AKI for elderly septic patients with AKI was about 50%, who had a worse prognosis as compared with non-septic AKI patients. The higher the stage of KDIGO, the higher the mortality in elderly septic patients with AKI was. RRT can decrease the rate of mechanical ventilation, whereas, it may not improve the prognosis of elderly septic patients with AKI.

Background Intraoperative hypotension is a risk factor for postoperative acute kidney injury (AKI). Elderly patients are susceptible due to reduced responses to acute hemodynamic changes. Aims Determine the association between hypotension identified from anesthetic charts and postoperative AKI in elderly patients. Methods Retrospective cohort study of elective noncardiac surgery patients ≥65 years, at an Australian tertiary hospital (December 2019–March 2021), with the primary outcome of AKI ≤48 h of surgery. Factors of interest were intraoperative hypotension determined from anesthetic charts (mean arterial pressure <60 mmHg, systolic blood pressure <90 mmHg, recorded 5-min) and intraoperative vasopressor use. Results In 830 patients (mean age 75 years), systolic hypotension was more frequent than mean arterial hypotension (25.7% vs. 11.9%). Most hypotensive episodes were brief (7.2% of systolic and 4.2% of mean arterial hypotension lasted >10 min) but vasopressors were used in 84.7% of cases. The incidence of postoperative AKI was 13.9%. Systolic hypotension >20 min was associated with AKI (OR, 3.88; 95% CI: 1.38–10.9), which was not significant after adjusting for vasopressors, creatinine, American Society of Anesthesiologists class, and hemoglobin drop. The cumulative dose of any specific vasopressor >20 mg (or >10 mg epinephrine) was independently associated with AKI (adjusted OR, 2.47; 95% CI: 1.34–4.58). Every 5 mg increase in the total dose of all intraoperative vasopressors used during surgery was associated with 11% increased odds of AKI (95% CI: 3–19%). Conclusions High vasopressor use was associated with postoperative AKI in elderly patients undergoing noncardiac surgery, independent of hypotension identified from anesthetic charts.

Background Bispectral index (BIS) is a processed electroencephalography monitoring tool and is widely used in anesthetic depth monitoring. Deep anesthesia exposure may be associated with multiple adverse outcomes. However, the relationship between anesthetic depth and postoperative acute kidney injury (AKI) remains unclear. We sought to determine the effect of BIS-based deep anesthesia duration on postoperative AKI following noncardiac surgery. Methods This retrospective study used data from the Vital Signs DataBase, including patients undergoing noncardiac surgeries with BIS monitoring. The BIS values were collected every second during anesthesia. Restricted cubic splines and logistic regression were used to assess the association between the cumulative duration of deep anesthesia and postoperative AKI. Results 4774 patients were eligible, and 129 (2.7%) experienced postoperative AKI. Restricted cubic splines showed that a cumulative duration of BIS < 45 was nonlinearly associated with postoperative AKI (P-overall = 0.033 and P-non-linear = 0.023). Using the group with the duration of BIS < 45 less than 15 min as the reference, ORs of postoperative AKI were 2.59 (95% confidence interval [CI]:0.60 to 11.09, p = 0.200) in the 15–100 min group, and 4.04 (95%CI:0.92 to 17.76, p = 0.064) in the ≥ 100 min group after adjusting for preoperative and intraoperative covariates in multivariable logistic regression. Conclusions The cumulative duration of BIS < 45 was independently and nonlinearly associated with the risk of postoperative AKI in patients undergoing noncardiac surgery.

Background This study aimed to develop and validate a nomogram for predicting acute kidney injury (AKI) in elderly patients in the intensive care unit (ICU). Methods Population data regarding elderly patients in ICU were derived from the Medical Information Mart for Intensive Care IV database from 2008 to 2019. The nomogram model was constructed from the training set using LASSO regression and logistic regression analysis, and the performance of the model was evaluated by decision curve analysis, calibration curve, and receiver operating characteristic (ROC) curve. Results According to inclusion and exclusion criteria, 14,373 elderly ICU patients were studied, of which 10,061 (70%) were assigned to the training set, and 4,312 (30%) were allocated to the validation set. Multivariate logistic analysis revealed that age, weight, myocardial infarction, congestive heart failure, dementia, diabetes, paraplegia, cancer, sepsis, body temperature, blood urea nitrogen, mechanical ventilation, urine volume, Sequential Organ Failure Assessment (SOFA) score, and Simplified Acute Physiology Score II (SAPS II) were independent risk factors for AKI in elderly ICU patients. The AUC values for the 15-factor nomogram were 0.812 (95% CI 0.802–0.822) and 0.802 (95% CI 0.787–0.818) in the training and validation sets, respectively. For clinical application, a simplified nomogram was constructed, which included age, weight, urine volume, SOFA score, and SAPS II, with the AUCs of 0.780 (95% CI 0.769–0.790) and 0.776 (95% CI 0.760–0.793), respectively. Calibration curve and decision curve analyses confirmed the models’ high prediction accuracy and clinical value. Conclusions The nomogram developed in this study shows excellent predictive performance for AKI in elderly patients in the ICU.

Acute kidney injury (AKI) is a critical postoperative complication in non-cardiac surgery patients, significantly impacting patient outcomes. The neutrophil percentage-to-albumin ratio (NPAR) is a promising inflammatory biomarker for predicting AKI. However, it is still unclear whether NPAR could be used as a predictor of postoperative AKI in Non-Cardiac Surgical Patients. Univariate and multivariable logistic regression analyses were conducted to assess the predictive value of NPAR for postoperative AKI, controlling for potential confounders. A total of 3041 patients were considered for the analysis after excluding those with preoperative infections and chronic kidney disease. The area under the receiver operating characteristic (ROC) curve for NPAR was 0.723, indicating moderate predictive capability for postoperative AKI. The optimal threshold for NPAR was 5.310, with a specificity of 0.640 and a sensitivity of 0.729. Multivariable regression analysis revealed that NPAR was significantly associated with postoperative AKI risk (adjusted odds ratio 1.093, 95% CI 1.072–1.116, P < 0.001), independent of other clinical factors. Preoperative NPAR is a significant predictor of postoperative AKI in non-cardiac surgical patients under general anesthesia and could be a valuable biomarker for identifying non-cardiac surgical patients at high-risk of AKI.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-12949-w.

Case reports and small retrospective studies have suggested that there is an increased risk of postoperative euglycemic ketoacidosis (eKA) and acute kidney injury (AKI) among patients using sodium-glucose cotransporter 2 inhibitors (SGLT2i) preoperatively. However, there has not been a representative assessment of the risks of these agents among patients undergoing surgery. To evaluate the risk of postoperative eKA, AKI, and mortality within 30 days after surgery among preoperative long-term SGLT2i users compared with nonusers. This is a multicenter, propensity-matched, retrospective case-control study from the Veterans Affairs Health Care System (VAHCS) National Registry performed from January 1, 2014, to December 31, 2022. Adult patients using SGLT2i preoperatively who underwent inpatient surgical procedures were compared with a 1:5 matched control group using propensity score matching, including the patient's demographic characteristics, comorbidities, and surgical characteristics. Data analysis was performed from June 2023 to August 2024. Long-term use of SGLT2i, defined as having more than 3 fills of outpatient prescription or less than a 180-day gap of the last fill according to the VAHCS pharmacy registries. The primary outcome was the rate of postoperative eKA among SGLT2i users vs control patients. Secondary outcomes included postoperative AKI and 30-day mortality after surgery. Among 462 968 patients undergoing surgery, 7448 SGLT2i users (mean [SD] age, 67.7 [8.1] years; 7204 [96.7%] male) and 455 520 nonusers (mean [SD] age, 65.8 [11.0] years; 424 785 [93.3%] male) were identified. After propensity score matching, 7439 patients were identified as SGLT2i users and compared with 33 489 control patients. SGLT2i use was associated with an increased risk of eKA (odds ratio [OR], 1.11; 95% CI, 1.05-1.17) but reduced risks of perioperative AKI (OR, 0.69; 95% CI, 0.62-0.78) and 30-day mortality (OR, 0.70; 95% CI, 0.55-0.88). The mortality rate 30 days after surgery was 1.1% among SGLT2i users vs 1.6% among control patients. The median hospital length of stay among the patients presenting with eKA increased by 3 days (median [IQR], 6 [3-10] days for those with eKA vs 3 [2-6] days for those without eKA). Patients treated with SGLT2i had a small but significantly higher risk of postoperative eKA but lower risks of postoperative AKI and 30-day mortality.

Acute kidney injury (AKI) poses a significant concern in elderly patients undergoing laparoscopic abdominal surgery due to increased vulnerability arising from aging, comorbidities, and surgery-related factors. Early detection and intervention are crucial for mitigating short- and long-term consequences. This study aims to investigate the correlation between preoperative Geriatric Nutritional Risk Index (GNRI), neutrophil-to-lymphocyte ratio (NLR), and the occurrence of postoperative AKI in elderly patients undergoing laparoscopic abdominal surgery, as well as to assess the predictive value of their combined detection for postoperative AKI. A retrospective study involving 347 elderly patients (aged 60 years or older) undergoing laparoscopic abdominal surgery explored the relationship between preoperative GNRI, NLR, and postoperative AKI. GNRI was calculated based on serum albumin and body weight ratios, while NLR was derived from preoperative blood tests. The combined GNRI and NLR test demonstrated superior predictive value (area under the curve [AUC] = 0.87) compared to individual markers. Multivariate logistic analysis identified age, American Society of Anesthesiologists (ASA) grade, comorbidities, preoperative GNRI, and NLR as independent risk factors for AKI. Correlation analysis affirmed a negative correlation between preoperative GNRI and AKI severity, and a positive correlation between preoperative NLR and AKI severity. The preoperative GNRI and NLR have clinical values in predicting postoperative AKI in elderly patients undergoing laparoscopic abdominal surgery.

Background and Objectives: Hip fracture surgery, which affects quality of life, can be a major challenge in geriatric populations. Although sarcopenia is known to be associated with postoperative outcomes, there are few studies on the association between sarcopenia and postoperative acute kidney injury (AKI) in this population. We investigated the association between sarcopenia and postoperative AKI in elderly patients following hip fracture surgery. Materials and Methods: We retrospectively reviewed the records of patients who underwent hip fracture surgery at our institution from March 2019 to December 2021. Patients under the age of 65, patients with no preoperative computed tomography (CT) scans and patients with inappropriate cross-sectional images for measurement were excluded. The psoas-lumbar vertebral index (PLVI), which is the ratio of the average area of both psoas muscles to the area of the fourth lumbar vertebral body, was measured from preoperative CT scans. Sarcopenia was defined as a PLVI within the lowest 25% for each sex, and patients were categorized into sarcopenic and nonsarcopenic groups. The occurrence of AKI was determined based on the serum creatinine level within postoperative day 7 using the Kidney Disease Improving Global Outcomes (KDIGO) guidelines. Univariate and multivariate logistic regression analyses were performed to evaluate the associations between clinical variables and the occurrence of AKI. Results: Among the 348 enrolled patients, 92 patients were excluded, and 256 patients were analyzed. The PLVI cutoff values for defining sarcopenia lower than 25% for male and female patients were 0.57 and 0.43, respectively. The overall incidence of AKI was 18.4% (47 patients), and AKI occurred more frequently in sarcopenic patients than in nonsarcopenic patients (29.7% vs. 14.6%, p = 0.007). According to the multivariate logistic regression, which included all variables with a p value &lt; 0.05 in the univariate analysis and adjusted for age, body mass index (BMI) and American Society of Anesthesiologists (ASA) physical status, sarcopenia was revealed to be an independent predictor of postoperative AKI (odds ratio = 5.10, 95% confidence interval = 1.77–14.77; p = 0.003). Conclusions: Preoperative sarcopenia, which corresponds to the lowest quartile of PLVI values, is associated with postoperative AKI among elderly patients who underwent hip fracture surgery.

ObjectiveRecent studies have indicated that patients (both with and without diabetes) with elevated hemoglobin A1c (HbA1c) have a higher rate of acute kidney injury (AKI) following cardiac surgery. However, whether HbA1c could help to predict post-operative AKI in patients after non-cardiac surgery is less clear. This study aims to explore the predictive value of pre-operative HbA1c for post-operative AKI in non-cardiac surgery.MethodsWe reviewed the medical records of patients (≥ 18 years old) who underwent non-cardiac surgery between 2011 and 2020. Patient-related variables, including demographic and laboratory and procedure-related information, were collected, and univariable and multivariable logistic regression analyses were performed to determine the association of HbA1c with AKI. The area under the receiver operating curve (AUC), net reclassification improvement index (NRI), and integrated discriminant improvement index (IDI) were used to evaluate the predictive ability of the model, and decision curve analysis was used to evaluate the clinical utility of the HbA1c-added predictive model.ResultsA total of 3.3% of patients (94 of 2,785) developed AKI within 1 week after surgery. Pre-operative HbA1c was an independent predictor of AKI after adjustment for some clinical variables (OR comparing top to bottom quintiles 5.02, 95% CI, 1.90 to 13.24, P < 0.001 for trend; OR per percentage point increment in HbA1c 1.20, 95% CI, 1.07 to 1.33). Compared to the model with only clinical variables, the incorporation of HbA1c increased the model fit, modestly improved the discrimination (change in area under the curve from 0.7387 to 0.7543) and reclassification (continuous net reclassification improvement 0.2767, 95% CI, 0.0715 to 0.4818, improved integrated discrimination 0.0048, 95% CI, -5e-04 to 0.0101) of AKI and non-AKI cases, NRI for non-AKI improvement 0.3222, 95% CI, 0.2864 to 0.3580 and achieved a higher net benefit in decision curve analysis.ConclusionElevated pre-operative HbA1c was independently associated with post-operative AKI risk and provided predictive value in patients after non-cardiac surgery. HbA1c improved the predictive power of a logistic regression model based on traditional clinical risk factors for AKI. Further prospective studies are needed to demonstrate the results and clinical application.

In an observational study including 33,330 noncardiac surgeries performed in 27,381 patients with detailed intraoperative blood pressures, Walsh et al.1 showed that intraoperative mean arterial pressure less than 55 mmHg was associated with the development of postoperative acute kidney and myocardial injuries. This study makes an important contribution to the effort to define risk factors for acute vital organ injury after surgery. Strengths of this study include the large sample of patients and adjust for most of the known risk factors that can affect acute kidney and myocardial injuries after surgery. Furthermore, the authors openly discuss the limitations of their work. However, in our view, there are several aspects of this study design that should be discussed and clarified.First, the body mass index and ethnicity were not included in the basic demographic data of patients for analysis and adjustment. It has been shown that in the noncardiac surgery patients, body mass index is independently associated with risk for postoperative acute kidney injury (AKI).2,3 Furthermore, obesity is an independent predictor of perioperative cardiac adverse events.4 In a retrospective study including 975,825 patients undergoing colorectal surgery, Masoomi et al.5 find that black race is associated with higher risk of postoperative AKI. Their trial design did also not include the detail about anesthesia techniques and intraoperative managements. Consequently, it is difficult to estimate the extent to which interventions by anesthesiologists might have influenced outcomes. A retrospective analysis including 9,171 patients undergoing joint-replacement operations shows that use of general anesthesia is independently associated with risk for postoperative AKI.2 Besides the transfusion volume adjusted by this study, other intraoperative managements, such as total vasopressor dose administered, use of a vasopressor infusion, and diuretic administration, have been shown to be independent predictors of postoperative AKI.3 In addition, intraoperative hypoxemia, tachycardia, and hypertension are associated independently with increased risk of myocardial injury after noncardiac surgery.6,7 Thus, we cannot exclude the possibility that the above confounding factors would have contributed to final analysis of their results.Second, this study assessed occurrence of acute kidney and myocardial injuries within 7 days after surgery. However, the authors did not mention specific measurement times of serum creatinine, troponin T, and creatinine kinase-MB after surgery. In addition, the study design did not include the detail about postoperative recovery and managements of patients. Thus, this study cannot provide enough evidence to support that all kidney and myocardial injuries occurred within 7 days after surgery are attributed to intraoperative hypotension. Actually, serum troponin appears at 30 min to 6 h after myocardial injury.8 Although serum creatinine lags behind acute changes in renal function, but AKI (defined by a 50% or more increase in serum creatinine) by intraoperative causes can be often detected between 1 and 3 days after surgery.9 For early detection of the potential kidney and myocardial injuries by intraoperative factors, we would suggest that the related serum biomarkers be measured as soon as possible after surgery, especially for patients who are at high risk of kidney and myocardial injuries. To prevent new kidney and myocardial injuries or avoid aggravation of existing organ injury by postoperative low perfusion, we emphasize that perioperative hemodynamic optimization of noncardiac surgery patients should be continued to the postoperative period, modifying prognosis of patients.Finally, 506 patients (1.5%) died within 30 days of surgery in this study. The authors should provide the detailed reasons of all death cases through analyzing death certificates, medical records, and autopsy reports, as described in previous studies.7,10 We would like to know how many of patients with postoperative AKI received kidney-replacement treatment, and how many of deaths are directly related to postoperative acute kidney and myocardial injuries. In addition, the authors should assess association between severity of postoperative acute vital organ and 30-day mortality. All these will help explore whether there is a causal relationship between postoperative acute vital organ injury and mortality or whether acute vital organ injury merely indicates a worse outcome.The authors declare no competing interests.