AKI in the very elderly patients without preexisting chronic kidney disease: a comparison of 48-hour window and 7-day window for diagnosing AKI using the KDIGO criteria

Early and minimal changes in serum creatinine can predict prognosis in elderly patients receiving invasive mechanical ventilation: A retrospective observational study

Background

Emerging evidence suggests that minimal acute kidney injury (stage 1 AKI) is associated with increased hospital mortality rates. However, for those who do not meet the AKI diagnostic criteria, whether a small increase in serum creatinine (SCr) levels is associated with an increased mortality rate in elderly patients is not known. Therefore, we aimed to investigate small elevations in SCr of <26.5 µmol/L within 48 h after invasive mechanical ventilation (MV) on the short-term mortality of critically ill patients in the geriatric population.

Methods

We conducted a retrospective, observational, multicenter cohort study enrolling consecutive elderly patients (≥75 years) who received invasive MV from January 2008 to December 2020. Recursive partitioning was used to calculate the ratio of SCr rise from baseline within 48 h after MV and divided into six groups, (1) <10%, (2) 10%-<20%, (3) 20%-<30%, (4) 30%-<40%, (5) 40%-<50%, and (6) ≥50%, where the reference interval was defined as the ratio <10% based on an analysis, which confirmed that the lowest mortality risk was found in this range. Clinical data and laboratory data were noted. Their general conditions and clinical characteristics were compared between the six groups. Prognostic survival factors were identified using Cox regression analysis. Kaplan-Meier survival analysis was employed for the accumulative survival rate.

Results

A total of 1292 patients (1171 men) with a median age of 89 (interquartile range: 85-92) with MV were suitable for further analysis. In all, 376 patients had any stage of early AKI, and 916 patients had no AKI. Among 916 non-AKI patients, 349 patients were in the ratio <10%, 291 in the 10%-<20% group, 169 in the 20%-<30% group, 68 in the 30%-<40% group, 25 in the 40%-<50% group, and 14 in the ≥50% group. The 28-day mortality rates in the six groups from the lowest (<10%) to the highest (≥50%) were 8.0%, 16.8%, 28.4%, 54.4%, 80.0%, and 85.7%, respectively. In the multivariable-adjusted analysis, patients with a ratio of 10%-<20% (hazard ratio [HR]=2.244; 95% confidence interval [CI]: 1.410 to 3.572; P=0.001), 20%-<30% (HR=3.822; 95% CI: 2.433 to 6.194; P <0.001), 30%-<40% (HR=10.472; 95% CI: 6.379 to 17.190; P <0.001), 40%-<50% (HR=13.887; 95% CI: 7.624 to 25.292; P <0.001), and ≥50% (HR=13.618; 95% CI: 6.832 to 27.144; P <0.001) had relatively higher 28-day mortality rates. The 90-day mortality rates in the six strata were 30.1%, 35.1%, 45.0%, 60.3%, 80.0%, and 85.7%, respectively. Significant interactions were also observed between the ratio and 90-day mortality: patients with a ratio of 10%-<20% (HR=1.322; 95% CI: 1.006 to 1.738; P=0.045), 20%-<30% (HR=1.823; 95% CI: 1.356 to 2.452; P <0.001), 30%-<40% (HR=3.751; 95% CI: 2.601 to 5.410; P <0.001), 40%-<50% (HR=5.735; 95% CI: 3.447 to 9.541; P <0.001), and ≥50% (HR=6.305; 95% CI: 3.430 to 11.588; P <0.001) had relatively higher 90-day mortality rates.

Conclusions

Our study suggests that a ≥ 10% SCr rise from baseline within 48 h after MV was independently associated with short-term all-cause mortality in mechanically ventilated elderly patients.

Trends in clinical outcomes of older hemodialysis patients: data from the 2023 Korean Renal Data System (KORDS)

With an increasing aging population, the mean age of patients with end-stage kidney disease (ESKD) is globally increasing. However, the current clinical status of elderly patients undergoing hemodialysis (HD) is rarely reported in Korea. The current study analyzed the clinical features and trends of older patients undergoing HD from the Korean Renal Data System (KORDS) database. The patients were divided into three groups according to age: <65 years (the young group), n = 50,591 (35.9%); 65-74 years (the younger-old group), n = 37,525 (26.6%); and ≥75 years (the older-old group), n = 52,856 (37.5%). The proportion of older-old group undergoing HD significantly increased in incidence and decreased in prevalence from 2013 to 2022. The median levels of hemoglobin, serum creatinine, albumin, calcium, phosphorus, and intact parathyroid hormone significantly decreased in the older-old group. The proportions of arteriovenous fistula creation and left forearm placement showed decreased trends with age. Although the utilization of low surface area dialyzers increased with age, the dialysis adequacy, including urea reduction ratio and Kt/V was within acceptable range in the older-old group on HD. Over the past 20 years, the mortality rate in the older-old group has increased, with cardiovascular diseases decreasing and infectious diseases increasing. The incidence of elderly patients undergoing HD has increased over time, but the high mortality of the older-old group needs to be solved. Therefore, it is imperative to develop holistic strategies based on age and individual needs for patients with ESKD.

Novel Plasma Biomarker-Based Model for Predicting Acute Kidney Injury After Cardiac Surgery: A Case Control Study

Introduction:

Acute kidney injury (AKI) after cardiac surgery is independently associated with a prolonged hospital stay, increased cost of care, and increased post-operative mortality. Delayed elevation of serum creatinine (SCr) levels requires novel biomarkers to provide a prediction of AKI after cardiac surgery. Our objective was to find a novel blood biomarkers combination to construct a model for predicting AKI after cardiac surgery and risk stratification.

Methods:

This was a case-control study. Weighted Gene Co-expression Network Analysis (WGCNA) was applied to Gene Expression Omnibus (GEO) dataset GSE30718 to seek potential biomarkers associated with AKI. We measured biomarker levels in venous blood samples of 67 patients with AKI after cardiac surgery and 59 control patients in two cohorts. Clinical data were collected. We developed a multi-biomarker model for predicting cardiac-surgery-associated AKI and compared it with a traditional clinical-factor-based model.

Results:

From bioinformatics analysis and previous articles, we found 6 potential plasma biomarkers for the prediction of AKI. Among them, 3 biomarkers, such as growth differentiation factor 15 (GDF15), soluble suppression of tumorigenicity 2 (ST2, IL1RL1), and soluble urokinase plasminogen activator receptor (uPAR) were found to have prediction ability for AKI (area under the curve [AUC] > 0.6) in patients undergoing cardiac surgery. They were then incorporated into a multi-biomarker model for predicting AKI (C-statistic: 0.84, Brier 0.15) which outperformed the traditional clinical-factor-based model (C-statistic: 0.73, Brier 0.16).

Conclusion:

Our research validated a promising plasma multi-biomarker model for predicting AKI after cardiac surgery.

The Association of Matrix Metalloproteinases With Acute Kidney Injury Following CPB-Supported Cardiac Surgery

BACKGROUND

Cardiac surgery-associated acute kidney injury (AKI) is an adverse outcome that increases morbidity and mortality in patients undergoing cardiac surgical procedures. To date, the use of serum creatinine levels as an early indicator of AKI has limitations because of its slow rise and poor predictive accuracy for renal injury. This delay in diagnosis may lead to prolonged initiation in treatment and increased risk for adverse outcomes.

OBJECTIVE

This pilot study explores serum and urine matrix metalloproteinases (MMPs)-2 and MMP-9 and their association, and potentially earlier detection of AKI in patients following cardiopulmonary bypass (CPB)-supported cardiac surgery. We hypothesize that increased activity of serum and urine levels MMP-2 and/ or MMP-9 are associated with AKI. Furthermore, MMP-2 and/ or MMP-9 may provide earlier identification of AKI as compared with serum levels of creatinine.

METHODS

During the study period, there were 150 CPB-supported surgeries, 21 of which developed AKI according to the Kidney Disease Improving Global Outcomes criteria. We then selected a sample of 21 matched cases from those patients who went through the surgery without developing AKI. Primary outcomes were the measurement via gel zymography of the serum and urine activity of MMP-2 and MMP-9 drawn at the following intervals: pre-CPB; 10-minute post-CPB; and 4-hour post-CPB time points. Secondary variables were the measurement of serum creatinine, intensive care unit (ICU) fluid balance, and length of ICU stay.

RESULTS

At the 10-minute and 4-hour post-CPB time points, the serum MMP-2 activity of AKI patients were significantly higher as compared with non-AKI patients (P < .001 and P = .004), respectively. Similarly, at the 10-minute and 4-hour post-CPB time points, the serum MMP-9 activity of AKI patients was significantly higher as compared with non-AKI patients (P = .001 and P = .014), respectively. The activity of urine MMP-2 and MMP-9 of AKI patients was significantly higher as compared with non-AKI patients at all 3 time points (P = .004, P < .001, P < .001), respectively.

CONCLUSION

Although the pilot study may have limitations, it has demonstrated that the serum and urine levels of activity of MMP-2 and MMP-9 are associated with the clinical endpoint of AKI and appear to have earlier rising levels as compared with those of serum creatinine. Furthermore, in depth, exploration is underway with a larger sample size to attempt validation of the analytical performance and reproducibility of the assay for MMP-2 and MMP-9 to aid in earlier diagnosis of AKI following CPB-supported cardiac surgery.

Effects of the diagnostic window and duration of acute kidney injury on 1-year mortality in elderly patients: a single-center retrospective study

BACKGROUND

We evaluated the prognostic impact of AKI duration on the 1-year mortality rate in elderly patients diagnosed based on the 48-hour and 7-day changes in serum creatinine (Scr) levels recommended by the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines.

METHODS

This retrospective study was conducted from 2007 to 2018 on elderly patients in the Geriatric Department of the Chinese PLA General Hospital. Based on the two diagnostic criteria in the KDIGO guidelines, the patients were divided into a 48-hour diagnostic window and a 7-day diagnostic window group, and into transient AKI (lasting 1-2 days) and persistent AKI (lasting 3-6 days, and ≥ 7 days) based on the time at which the Scr level returned to the baseline value. The primary outcome was the 1-year mortality rate after AKI.

RESULTS

In total, 688 patients were enrolled, including 367 (53.3%) with a 48-hour and 321 (46.7%) with a 7-day diagnostic window. Of the 688 patients, in the 48-hour window group, 12.0% had transient AKI, 31.1% had lasting 3-6 days, and 56.9% had lasting ≥ 7 days; in the 7-day window group, 5.3% had transient AKI, 24.0% had lasting 3-6 days, and 70.7% had lasting ≥ 7 days. Overall, 332 patients (33.6%) died within 1 year, including 189 (51.5%) in the 48-hour and 143 (44.5%) in the 7-day diagnostic window group. After adjusting for multiple covariates, AKI duration was associated with a significantly higher 1-year mortality rate (3-6 days: HR = 3.535; 95% CI = 1.685-7.417, P = 0.001; ≥ 7 days: HR = 2.400; 95% CI = 1.152-5.001, P = 0.019) in the 48-hour diagnostic window group, but it did not differ in the 7-day diagnostic window group (P = 0.452).

CONCLUSIONS

Persistent AKI was common in elderly hospitalized patients, accounting for 88% and 95% of patients with 48-hour and 7-day diagnostic windows, respectively. Moreover, AKI duration was associated with different clinical outcomes depending on the diagnostic window. Further studies should focus on the mechanism underlying the relationship of AKI outcomes with diagnostic criteria.

Targeting Premature Renal Aging: from Molecular Mechanisms of Cellular Senescence to Senolytic Trials

The biological process of renal aging is characterized by progressive structural and functional deterioration of the kidney leading to end-stage renal disease, requiring renal replacement therapy. Since the discovery of pivotal mechanisms of senescence such as cell cycle arrest, apoptosis inhibition, and the development of a senescence-associated secretory phenotype (SASP), efforts in the understanding of how senescent cells participate in renal physiological and pathological aging have grown exponentially. This has been encouraged by both preclinical studies in animal models with senescent cell clearance or genetic depletion as well as due to evidence coming from the clinical oncologic experience. This review considers the molecular mechanism and pathways that trigger premature renal aging from mitochondrial dysfunction, epigenetic modifications to autophagy, DNA damage repair (DDR), and the involvement of extracellular vesicles. We also discuss the different pharmaceutical approaches to selectively target senescent cells (namely, senolytics) or the development of systemic SASP (called senomorphics) in basic models of CKD and clinical trials. Finally, an overview will be provided on the potential opportunities for their use in renal transplantation during ex vivo machine perfusion to improve the quality of the graft.

Molecular Mechanisms of AKI in the Elderly: From Animal Models to Therapeutic Intervention

Acute kidney injury (AKI), a critical syndrome characterized by a sudden reduction of renal function, is a common disorder among elderly patients particularly in Intensive Care Unit (ICU). AKI is closely associated with both short- and long-term mortality and length of hospital stay and is considered a predictor of chronic kidney disease (CKD). Specific hemodynamic, metabolic, and molecular changes lead to increased susceptibility to injury in the aged kidney; therefore, certain causes of AKI such as the prerenal reduction in renal perfusion or vascular obstructive conditions are more common in the elderly; moreover, AKI is often multifactorial and iatrogenic. Older patients present several comorbidities (diabetes, hypertension, heart failure) and are exposed to multiple medical interventions such as the use of nephrotoxic contrasts media and medications, which can also trigger AKI. Considering the emerging relevance of this condition, prevention and treatment of AKI in the elderly should be crucial in the internist and emergency setting. This review article summarizes the incidence, the risk factors, the pathophysiology, the molecular mechanisms and the strategies of prevention and treatment of AKI in elderly patients.

Analysis of the short-term prognosis and risk factors of elderly acute kidney injury patients in different KDIGO diagnostic windows

Background and aims

Follow-up observation was performed on elderly acute kidney injury (AKI) patients to analyze the short-term prognosis and risk factors of AKI patients in the 48-h diagnostic window and 7-day diagnostic window of the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines.

Methods

Inpatients aged ≥ 75 years in the geriatric ward of the People’s Liberation Army General Hospital, China, between January 2007 and December 2015 were selected as the research subjects. According to two diagnostic criteria in the KDIGO guidelines, patients were divided into a 48-h diagnostic window group and a 7-day diagnostic window group. The medical data of the patients were divided into the death group and the survival group for analysis based on the survival condition of the patients after 90 days of AKI. Factors that affected the 90-day survival of patients in the 48-h diagnostic window and 7-day diagnostic window groups were analyzed using multivariate Cox regression.

Results

During the follow-up period, a total of 652 patients were enrolled in this study. Among them, 623 cases were men, accounting for 95.6% of the patients. The median age was 87 (84–91) years. According to the KDIGO staging criteria, there were 308 (47.2%) cases in AKI stage 1, 164 (25.2%) cases in stage 2, and 180 (27.6%) cases in stage 3. Among the 652 patients, 334 (51.2%) were diagnosed with AKI based on the 48-h diagnostic criteria window, and 318 (48.8%) were diagnosed with AKI based on the baseline 7-day diagnostic criteria. The 90-day mortality of AKI patients was 42.5% in the 48-h diagnostic window and 24.2% in the 7-day diagnostic window. The multivariate Cox analysis results showed that low mean arterial pressure (HR = 0.966; P < 0.001), low serum prealbumin level (HR = 0.932; P < 0.001), infection (HR = 1.448; P = 0.047), mechanical ventilation (HR = 1.485; P = 0.038), high blood urea nitrogen (BUN) level (HR = 1.026; P < 0.001), blood magnesium level (HR = 2.560; P = 0.024), and more severe AKI stage (stage 2: HR = 3.482; P < 0.001 and stage 3: HR = 6.267; P < 0.001) were independent risk factors affecting the 90-day mortality of elderly patients in the 48-h diagnostic window, whereas low body mass index (HR = 0.851; P < 0.001), low mean arterial pressure (HR = 0.980; P = 0.036), low serum prealbumin level (HR = 0.950; P = 0.048), low serum albumin level (HR = 0.936; P = 0.015), high BUN level (HR = 1.046; P < 0.001), and more severe AKI stage (stage 2: HR = 4.249; P = 0.001 and stage 3: HR = 9.230; P < 0.001) were independent risk factors affecting the 90-day mortality of elderly patients in the 7-day diagnostic window.

Conclusions

The clinical differences of AKI and risk factors for 90-day mortality in elderly AKI individuals vary depending on the definition used. An increment of Scr ≥ 26.5 μmol/L in 48 h (48-h KDIGO window) alone predicts adverse clinical outcomes.