Evaluation of the accuracy of estimated baseline serum creatinine for acute kidney injury diagnosis

Background

Modern epidemiologic studies of acute kidney injury (AKI) have been facilitated by the increasing availability of electronic medical records. However, pre-morbid reference serum creatinine (SCr) data are often unavailable in such records. Investigators substitute estimated baseline SCr with the eGFR 75 approach, instead of using actually measured baseline SCr. Here, we evaluated the accuracy of estimated baseline SCr for AKI diagnosis in the Japanese population.

Methods

Inpatients and outpatients aged 18–80 years were retrospectively enrolled. AKI was diagnosed according to the Kidney Disease Improving Global Outcomes (KDIGO) criteria, using SCr levels. The non-AKI and AKI groups were selected using the following criteria: increase 1.5 times greater than baseline SCr (“baseline SCr”) or increase 0.3 mg/dL greater than baseline SCr in 48 h (“increase in 48 h”). AKI accuracy defined by the estimated reference SCr, the average SCr value of the non-AKI population (eb-GFR-A approach), or the back-calculated SCr from fixed eGFR = 75 mL/min/1.73 m² (eGFR 75 approach, or, eb-GFR-B approach in this study), was evaluated.

Results

We analyzed data from 131,358 Japanese patients. The number of patients with reference baseline SCr in the non-AKI and AKI patients were 29,834 and 8952, respectively. For AKI patients diagnosed using “baseline SCr”, the AKI diagnostic accuracy rates as defined by eb-GFR-A and eb-GFR-B were 63.5 and 57.7%, respectively, while in AKI diagnosed using “increase in 48 h”, the AKI diagnostic accuracy rates as defined by eb-GFR-A and eb-GFR-B were 78.7 and 75.1%, respectively. In non-AKI patients, false-positive rates of AKI misdiagnosed via eb-GFR-A and eb-GFR-B were 7.4 and 6.8%, respectively.

Conclusions

AKI diagnosis using the average SCr value of the general population may yield more accurate results than diagnosis using the eGFR 75 approach when the reference SCr is unavailable.

     

Acute changes in fluid status affect the incidence,associative clinical outcomes,and urine biomarker performance in premature infants with acute kidney injury

Background

During the first postnatal weeks, infants have abrupt changes in fluid weight that alter serum creatinine (SCr) concentration, and possibly, the evaluation for acute kidney injury (AKI).

Methods

We performed a prospective study on 122 premature infants to determine how fluid adjustment (FA) to SCr alters the incidence of AKI, demographics, outcomes, and performance of candidate urine biomarkers. FA-SCr values were estimated using changes in total body water (TBW) from birth; FA-SCR?=?SCr × [TBW + (current wt. – BW)]/ TBW; where TBW?=?0.8 × wt in kg). SCr-AKI and FA-SCr AKI were defined if values increased by?≥?0.3 mg/dl from previous lowest value.

Results

AKI incidence was lower using the FA-SCr vs. SCr definition [(23/122 (18.8 %) vs. (34/122 (27.9 %); p?<?0.05)], with concordance in 105/122 (86 %) and discordance in 17/122 (14 %). Discordant subjects tended to have similar demographics and outcomes to those who were negative by both definitions. Candidate urine AKI biomarkers performed better under the FA-SCr than SCr definition, especially on day 4 and days 12–14.

Conclusions

Adjusting SCr for acute change in fluid weight may help differentiate SCr rise from true change in renal function from acute concentration due to abrupt weight change.

     

Comparison of different definitions of acute kidney injury in extremely low birth weight infants

Background

The definition of acute kidney injury (AKI) has evolved over the years, and three definitions have been adapted including pediatric risk injury failure, loss of kidney function (pRIFLE), Acute Kidney Injury Network (AKIN), and Neonatal Modified Kidney Disease Improving Global Outcomes (KDIGO). We sought to report the prevalence and outcome of (AKI) according to the three existing definitions in extremely low birth weight (ELBW) infants.

Methods

In a retrospective cohort study, medical records of all ELBW infants (<1000 g) admitted to our neonatal intensive care unit (NICU) between Jan 2002 and Dec 2011 were reviewed. Infants’ demographics, anthropometric measurements, and clinical characteristics were collected at the time of birth and at discharge from the NICU. Infants were staged according to the three different definitions.

Results

During the study period, 483 ELBW infants met our inclusion criteria. The incidence of AKI was 56, 59, and 60% according to pRIFLE, AKIN, and KDIGO, respectively. Mortality, NICU length of stay, and serum creatinine (SCr) at NICU discharge were higher in infants with advanced AKI stages regardless of the definition. In addition, discharge NICU weight and length z scores were lower in infants with advanced AKI stages. SCr at 72 h of life and SCr peak were predictable of NICU mortality [AUC 0.667 (95% CI 0.604–0.731), p < 0.001 and AUC 0.747 (95% CI 0.693–0.801), p < 0.001, respectively].

Conclusion

Regardless of the definition, advanced AKI is associated with increased mortality, prolonged NICU length of stay, and poor growth in ELBW infants. SCr at 72 h of life and SCr peak may be predictable of NICU mortality.

     

Clinical usefulness of urinary liver-type fatty-acid-binding protein as a perioperative marker of acute kidney injury in patients undergoing endovascular or open-abdominal aortic aneurysm repair

Purpose

Acute kidney injury (AKI) is common after cardiovascular surgery and is usually diagnosed on the basis of the serum creatinine (SCr) level and urinary output. However, SCr is of low sensitivity in patients with poor renal function. Because urinary liver-type fatty-acid-binding protein (L-FABP) reflects renal tubular injury, we evaluated whether perioperative changes in urinary L-FABP predict AKI in the context of abdominal aortic repair.

Methods

Study participants were 95 patients who underwent endovascular abdominal aortic aneurysm repair (EVAR) and 42 who underwent open repair. We obtained urine samples before surgery, after anesthesia induction, upon stent placement, before aortic cross-clamping (AXC), 1 and 2 h after AXC, at the end of surgery, 4 h after surgery, and on postoperative days (PODs) 1, 2, and 3, for measurement of L-FABP. We obtained serum samples before surgery, immediately after surgery, and on PODs 1, 2, and 3, for measurement of SCr. We also plotted receiver-operating characteristic (ROC) curves to identify cutoff laboratory values for predicting the onset of AKI.

Results

With EVAR, urinary L-FABP was significantly increased 4 h after the procedure (P = 0.014). With open repair, urinary L-FABP increased significantly to its maximum by 2 h after AXC (P = 0.007). With AKI, SCr significantly increased (P < 0.001, P = 0.001) by POD 2. ROC analysis showed urinary L-FABP to be more sensitive than SCr for early detection of AKI.

Conclusion

Urinary L-FABP appears to be a sensitive biomarker of AKI in patients undergoing abdominal aortic repair.

     

Transition from acute kidney injury to chronic kidney disease: a single-centre cohort study

Background

The incidence of acute kidney injury (AKI) is increasing. AKI is currently recognised as an inducer of chronic kidney disease (CKD) and this is known as the ‘AKI–CKD transition’. This study aimed to evaluate the rate of decline in estimated glomerular filtration rate (eGFR) associated with AKI events in individuals with and without pre-existing CKD.

Methods

Inpatients aged 18–80 years were retrospectively enrolled. AKI was diagnosed according to the kidney disease improving global outcomes (KDIGO) criteria using serum creatinine levels. Patients with a history of AKI events were divided into four groups according to eGFR before and after the AKI events. In each group, the eGFR levels after an AKI event were compared to those before the AKI event. Patients were further divided into eight groups according to clinical background based on underlying diseases, medications, and surgical history.

Results

We analysed data from 9651 patients with AKI. Not surprisingly, we found that eGFR levels during the first AKI event were significantly lower than levels before the event in each group. Furthermore, eGFR levels after the first AKI event were significantly lower than those before the first AKI event, and the eGFR levels after the second AKI event were significantly lower than those after the first AKI event. These trends were similar in each group irrespective of clinical background.

Conclusions

Our study revealed that AKI events can cause a decline in kidney function and, as more AKI events occur, acceleration of this decline.

     

Improving acute kidney injury management in lower limb arthroplasty: an educational approach

Introduction

Acute kidney injury (AKI) is a common but preventable cause of morbidity in elective arthroplasty patients. This study aimed to review the incidence and management of AKI in patients undergoing elective lower limb arthroplasty and compare results to those after the introduction of educational measures to improve prevention, recognition and management of AKI.

Methods

A retrospective case note review of all patients undergoing elective hip or knee arthroplasty between August and October 2013 was performed. Results were compared to patients treated from February to April 2014, after the introduction of a renal protection protocol, checklist poster and educational sessions. Results were statistically compared using Fisher’s exact test.

Results

Two hundred and eleven patients were included in the study: 104 in the initial cohort and 107 in the second cohort. Twenty patients (19.2 %) developed AKI in the initial cohort and 12 patients (11.2 %) in the second (p = 0.13). Recognition, documentation and management of AKI were significantly better following educational sessions and dissemination of posters throughout clinical areas, with 75 % of patients in the second cohort having their AKI documented and treated versus 30 % in the initial cohort.

Discussion/conclusions

This quality improvement project has demonstrated the significant impact that simple educational measures can have on improving AKI prevention, recognition and management in patients undergoing elective arthroplasty surgery. The introduction of a logical treatment checklist has been well received by both medical and nursing staff and ensures prompt and efficient management of AKI in a non-specialist area.

     

Prognostic Significance of Acute Kidney Injury Following Emergency Laparotomy: A Prospective Observational Cohort Study

Aims

Post-operative acute kidney injury (AKI) is a common and independent mortality risk factor carrying high clinical and economic cost. This study aimed to establish the incidence of AKI in patients undergoing emergency laparotomy (EL), to determine patients’ risk profile and consequent mortality.

Methods

Consecutive 239 patients of median age 68 (IQR 51–76) years, undergoing EL in a UK tertiary hospital, were studied. Primary outcome measure was AKI and in-hospital operative mortality.

Results

Ninety-five patients (39.7%) developed AKI, which was associated with in-hospital mortality in 32 patients (33.7%) compared with 7 patients (4.9%) without AKI. AKI occurred in 81.1% of all mortalities, but none occurred when AKI resolved within 48 h of EL. AKI was associated with chronic kidney disease, age, serum lactate, white cell count, pre-EL systolic blood pressure and tachycardia (p?<?0.010). Median length of hospital stay in AKI survivors was 15 days compared with 11 days in the absence of AKI (p?<?0.001). On multivariable analysis, only AKI at 48 h post-EL was significantly and independently associated with mortality [HR 10.895, 95% CI 3.152–37.659, p?<?0.001].

Conclusion

Peri-operative AKI after EL was common and associated with a more than sixfold significant greater mortality. Pre-operative risk profile assessment and prompt protocol-driven intervention should minimise AKI and reduce EL mortality.

     

Predictors of Perioperative Acute Kidney Injury in Obese Patients Undergoing Laparoscopic Bariatric Surgery: a Single-Centre Retrospective Cohort Study

Background

Obesity has been associated with increased risk of perioperative acute kidney injury (AKI). We aim to establish the incidence of AKI among patients undergoing laparoscopic bariatric surgery and identify potential risk factors.

Methods

Records of 1230 patients who underwent laparoscopic bariatric surgery in a tertiary centre from 1 December 2009 to 31 January 2014 were retrospectively studied. AKI diagnosis was made by comparing the baseline and post-operative serum creatinine to determine the presence of predefined significant change based on the Kidney Disease: Improving Global Outcomes (KDIGO) definition. Univariate analyses were performed to determine significant clinical factors, and multiple logistic regression analysis was subsequently done to determine independent predictors of AKI.

Results

Thirty-five (2.9 %) patients developed AKI during the first 72 h post-surgery. Multivariate logistic regression analysis revealed impaired renal function (OR 10.429, 95 % CI 3.560 to 30.552), use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers (OR 3.038, 95 % CI 1.352 to 6.824), and body mass index (OR 1.048, 95 % CI 1.005 to 1.093) as independent predictors of perioperative acute kidney injury in the obese patients who underwent laparoscopic bariatric surgery.

Conclusions

We found that the incidence of perioperative AKI among patients who underwent laparoscopic bariatric surgery is at 2.9 %. Impaired renal function, use of angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers and raised body mass index were found to be independent predictors of AKI. Patients with these risk factors could be considered at risk for developing perioperative AKI, and extra perioperative vigilance should be undertaken.

     

A detailed evaluation of the new acute kidney injury criteria by KDIGO in critically ill patients

Purpose

Two previous classifications of acute kidney injury (AKI) have shown that AKI is associated with increased mortality. In 2012, Kidney Disease Improving Global Outcomes (KDIGO) created new AKI criteria by combining the two previous classifications. However, such combination might cause inconsistency among each definition in the criteria. We have investigated all the definitions in the new KDIGO criteria.

Methods

We retrospectively studied 767 adult patients whose stay in the ICU exceeded 24 h. The KDIGO criteria were applied to all patients to diagnose AKI. Hospital mortality of patients with AKI diagnosed by the ten definitions in the criteria was compared.

Results

AKI occurred in 51.9 % with the standard definition of KDIGO. By multivariable analysis, odds ratios were increased with AKI stage progression and AKI stage 3 was significantly associated with hospital mortality. Crude hospital mortality stratified by the ten definitions showed increasing trends with stage progression. Mortality of the three definitions in stage 1 was from 4.0 to 10.8 %. Stage 2 had two definitions and their mortality was 13.6 and 17.6 %. Stage 3 had five definitions and their mortality ranged from 27.6 to 55.6 %.

Conclusion

AKI defined by the new KDIGO criteria was associated with increased hospital mortality. Although definitions in the KDIGO criteria seem to be appropriate because of the clear relationship between mortality and stage progression on the whole, several limitations may exist, especially in stage 3. Further research should be needed to clarify the validity of the KDIGO criteria and the detailed categories.

     

Timing of initiation of renal replacement therapy for acute kidney injury: a systematic review and meta-analysis of randomized-controlled trials

Background

The effects of early renal replacement therapy (RRT) on mortality and renal recovery in patients with acute kidney injury (AKI) remain controversial. A systematic review and meta-analysis of randomized-controlled trials (RCTs) was performed.

Methods

MEDLINE, EMBASE and the Cochrane Library database (Cochrane Central Register of Controlled Trials) were searched to identify RCTs, investigating the effects of early RRT on patients with AKI.

Results

Six studies with a total of 1257 participants were included in this meta-analysis. Compared to late RRT, early RRT did not reduce the risk of mortality (RR 0.93, 95 % CI 0.68–1.26) or affect renal recovery (RR 0.88, 95 % CI 0.48–1.62) or composite endpoint (death or dialysis dependence) (RR 0.91, 95 % CI 0.71–1.17). There was no significant difference in adverse events in the analysis, between the early RRT and late RRT arms.

Conclusions

Early initiation of RRT for patients with AKI is not associated with decreased overall mortality or a delayed renal recovery rate. The optimal time to initiate RRT remains uncertain. Large scale and adequately powered RCTs are needed to detect the effects of early initiation of RRT in AKI patients.

     

Acute kidney injury after heart transplant in young children: risk factors and outcomes

Background

Critical illness following heart transplantation can include acute kidney injury (AKI). Study objectives were to define the epidemiology of, risk factors for, or impact on outcomes of AKI after pediatric heart transplant.

Methods

Using data from a prospective study of 66 young children, we evaluated: (1) post-operative AKI rate (by pediatric modified RIFLE criteria); (2) pre, intra, and early post-operative AKI risk factors using stepwise logistic regression (3) effect of AKI on short-term outcomes (ventilation and length of pediatric intensive care unit (PICU) stay) using stepwise multiple regression.

Results

AKI occurred in 73 % of children. Pre-transplant ventilation and higher baseline estimated creatinine clearance (eCCl) were independent risk factors for AKI. Pre-operative inotrope use was associated with reduced risk of AKI. Tacrolimus level emerged as important in multivariable risk prediction. Children with AKI had a longer duration of ventilation and length of pediatric intensive care unit (PICU) stay, with AKI being an independent predictor.

Conclusions

AKI was common after heart transplant and associated with more complicated early post-transplant course. Lower baseline eCCl was associated with lower incidence of AKI; this merits further investigation. The association of pre-operative inotropes with less AKI may reflect a pathophysiological mechanism or be a surrogate for clinical factors and management prior to transplant. Avoiding high tacrolimus levels may be a modifiable risk factor for AKI.

     

RIFLE classification in geriatric patients with acute kidney injury in the intensive care unit

Background

The RIFLE classification is widely used to assess the severity of acute kidney injury (AKI), but its application to geriatric AKI patients complicated by medical problems has not been reported.

Methods

We investigated 256 geriatric patients (≥65 years old; mean age, 74.4 ± 6.3 years) who developed AKI in the intensive care unit (ICU) according to the RIFLE classification. Etiologic, clinical, and prognostic variables were analyzed.

Results

They were categorized into RIFLE-R (n = 53), RIFLE-I (n = 102), and RIFLE-F (n = 101) groups. The overall in-hospital mortality was 39.8 %. There were no significant differences in RIFLE category between survivors and non-survivors. Survivors had significantly less needs for a ventilator and vasopressor, and lower number of failing organs. Survivors had higher systolic blood pressure, hemoglobin level, and serum albumin levels. We performed a logistic regression analysis to identify the independent predictors of in-hospital mortality. In a univariate analysis, hypertension, chronic kidney disease, RIFLE classification, number of failing organs, need for a ventilator and vasopressor, systolic blood pressure, hemoglobin level, and serum albumin levels were identified as prognostic factors of in-hospital mortality. However, in a multivariate analysis, hypertension, chronic kidney disease, number of failing organs, and serum albumin levels were independent risk factors, with no significant difference for in-hospital mortality with the RIFLE classification.

Conclusion

The RIFLE classification might not be associated with mortality in geriatric AKI patients in the ICU. In geriatric patients with AKI, various factors besides severity of AKI should be considered to predict mortality.

     

Acute kidney injury after abdominal aortic aneurysm repair: current epidemiology and potential prevention

Purpose

Acute kidney injury (AKI) is a severe complication after infrarenal abdominal aortic aneurysm (iAAA) repair. Little data are available whether endovascular aneurysm (EVAR) or open aortic repair (OAR) differs with respect to AKI frequency and severity, consecutive development of chronic kidney disease (CKD) and potentially preventable and modifiable risk factors of AKI.

Patients and methods

We assessed AKI rates, AKI stages and CKD applying current, complete definitions from the kidney disease improving global outcomes initiative in propensity-score-matched cohorts of all patients with elective and urgent iAAA repair at our institution from 2007 to 2011. Risk factors were analysed using multivariate logistic regression analyses.

Results

From 268 patients, we identified 91 matched pairs who had undergone either EVAR or OAR. The AKI rate was 13.2% with EVAR versus 41.8% with OAR (P < 0.001). AKI was significantly less severe in EVAR. OAR patients lost more glomerular filtration rate (? 11.3 vs. ? 6.5%; P = 0.02) and developed more frequently CKD (14.3 vs. 3.2%; P < 0.001) 3 months after iAAA repair. EVAR, circulatory shock, radiocontrast media, rhabdomyolysis and sepsis were identified as potentially preventable or modifiable risk factors of AKI.

Conclusions

AKI is significantly less frequent and severe in iAAA patients after EVAR as compared to OAR. Furthermore OAR patients demonstrate a higher CKD rate. The identified risk factors may be prevented or modified as a bundle of measures especially in patients with pre-existing CKD to reduce AKI and its severity after iAAA repair.

     

Comparison of renal function detriments after local tumor ablation or partial nephrectomy for renal cell carcinoma

Purpose

Local tumor ablation (LTA) and partial nephrectomy (PN) represent treatment alternatives for patients diagnosed with small renal mass and both may result in renal function detriments. The aim of the study was to compare renal function detriments after LTA or PN.

Methods

A Surveillance epidemiology and End Results-Medicare-linked retrospective cohort of 2850 T1 kidney cancer patients who underwent LTA or PN was abstracted. Short-term outcomes consisted of 30-day acute kidney injury (AKI) and 30-day dialysis rates. Long-term outcomes consisted of episodes of AKI, mild and moderate–severe chronic kidney disease (CKD), end-stage renal disease, hemodialysis and anemia in CKD. Analyses consisted of propensity score matching, logistic and Cox regression.

Results

After propensity score matching, 1122 patients remained. The 30-day incidence of AKI was 4.6 % after LTA and 9.4 % after PN. In multivariable analyses (MVAs), LTA was associated with a lower AKI rate (OR 0.42; p = 0.001). The 30-day incidence of any dialysis was <2 % after either LTA or PN. In MVA, LTA was not associated with a lower rate of any dialysis (OR 0.43; p = 0.2). At long-term assessment, both the unadjusted and adjusted rates of all six examined end points were not different between LTA and PN (all p > 0.5).

Conclusions

LTA offers short-term protective effect from AKI. The short-term rates of any dialysis treatment are similar after either LTA or PN. At long-term assessment, LTA and PN renal function detriment rates are not different. Concern for long-term functional outcomes should not be a barrier for PN.

     

Nephrotoxicity of iodixanol versus iopamidol in patients undergoing peripheral angiography with or without endovascular therapy

Purpose

To compare the nephrotoxic effects of iodixanol and iopamidol in patients undergoing peripheral angiography.

Methods

Patients scheduled for peripheral angiography were randomly assigned to the iodixanol group (n?=?463) and iopamidol group (n?=?458). The primary endpoint was the incidence of contrast associated acute kidney injury (CA-AKI), which was defined as an increase?≥?25% or ≥?44.2 µmol/l (0.5 mg/dl) in serum creatinine (SCr) from baseline within 72 h after receiving contrast media (CM). The secondary endpoints were the mean peak SCr increase within 72 h after receiving CM and major adverse renal events (SCr increased by two times after 30 days, the need for dialysis treatment, rehospitalization for acute renal failure, or kidney-related death) during hospitalization and within 30 day postdischarge.

Results

The incidence of CA-AKI did not differ significantly between the iodixanol group and iopamidol group (18.1% vs. 16.8%; p?=?0.595). There was no significant difference in the mean peak SCr increase between the iodixanol group and iopamidol group (10.4?±?13.0 vs. 10.6?±?14.3 µmol/l, p?=?0.919). There were four patients [1 (0.2%) patient in the iodixanol group and 1 (0.7%) patients in the iopamidol group, p?=?0.609] with doubling of SCr; no other adverse renal events were observed.

Conclusions

Our data showed that the nephrotoxicity of iodixanol was comparable with that of iopamidol in patients undergoing peripheral angiography.

     

Serum NGAL and copeptin levels as predictors of acute kidney injury in asphyxiated neonates

Background

Acute kidney injury (AKI) is the most common complication of perinatal asphyxia. Recent research indicates that serum neutrophil gelatinase-associated lipocalin (NGAL) is an early marker for AKI, but there are the lacks of data about its use in term neonates with perinatal asphyxia.

Methods

A prospective cohort study was conducted on 43 term neonates. Umbilical cord blood and 24 h after birth serum NGAL, copeptin, creatinine, and molality were measured in all asphyxiated and controls neonates.

Results

During the study period, 8 of asphyxiated nenates (18.6 %) suffered from AKI, while 35 newborns have no signs of AKI and 30 healthy infants. We did not observe any differences in creatinine and copeptin levels, as well as serum osmolality in all three investigated groups (AKI, no-AKI, and controls) in cord blood, and 24 h after birth. Serum NGAL levels in umbilical cord blood were significantly higher in the AKI group (174.3 ng/mL) compared with no-AKI (88.5 ng/mL, p = 0.01) and control groups (28.5 ng/mL, p < 0.001), and 24 h after birth (respectively, AKI 152.5 ng/mL vs no-AKI 74.9 ng/mL, p = 0.02 vs controls 39.1 ng/mL, p < 0.001). NGAL concentration showed a strong negative correlation to umbilical artery pH (Rho = ?0.42, p = 0.04), base excess (Rho = ?0.31, p = 0.03), and Apgar score in 1st min (Rho = ?0.41, p = 0.02) and 5th min of life (Rho = ?0.20, p = 0.001). ROC curve analysis demonstrated a good predictive value for NGAL levels (>140.7 ng/mL) which allows to diagnose AKI in asphyxiated patients with 88.9 % sensitivity (95 % CI 75–95 %) and 95.0 % specificity (95 % CI 76–99 %).

Conclusion

NGAL seems to be a promising marker, even in subclinical AKI in neonates, due to its high specificity, but copeptin did not meet expectations.

     

Utility of fractional excretion of urea in the differential diagnosis of acute kidney injury in children

Introduction

The fractional excretion of sodium (FE_Na) has been used as an index for the differential diagnosis of acute tubular necrosis (ATN) and prerenal acute kidney injury (AKI). The reliability of this index, however, decreases with the use of the diuretic agent furosemide. The fractional excretion of urea nitrogen (FE_UN) has been shown to be useful in such settings in adults. The objective of this study was to examine whether FE_UN is also useful in these settings in children.

Methods

We assessed 102 episodes of AKI in 74 children, classifying these into three groups based on history, physical examination, urine examination and subsequent clinical course: (1) prerenal AKI without furosemide (N?=?37), (2) prerenal AKI with furosemide (N?=?32) and (3) ATN (N?=?33).

Results

Of the 37 prerenal AKI episodes without furosemide, 35 showed low FE_Na of <1 %, with an overall average of 0.35?±?0.11 %, whereas prerenal AKI with furosemide (1.63?±?0.37 %) and ATN (8.76?±?2.11 %) were associated with a higher FE_Na. FE_UN in the clinical setting of prerenal AKI was lower than that in ATN (27.9?±?2.1 vs. 51.6?±?3.8 %, respectively) and, in contrast to FE_Na, not significantly different between the categories of prerenal AKI with and without furosemide (29.2?±?3.1 vs. 25.1?±?2.9, respectively). The sensitivity of FE_UN <35 % was 75 % in prerenal AKI with furosemide, whereas that of FE_Na was 53 %.

Conclusions

FE_UN is useful in detecting prerenal AKI in children administered furosemide.

     

No difference in flexion power despite iliopsoas fatty degeneration in healed hip fractures with large lesser trochanter displacement

Objective

To evaluate iliopsoas atrophy and loss of function after displaced lesser trochanter fracture of the hip.

Design

Cohort study.

Setting

District hospital.

Patients

Twenty consecutive patients with pertrochanteric fracture and displacement of the lesser trochanter of?>?20 mm.

Intervention

Fracture fixation with either an intramedullary nail or a plate.

Outcome measurements

Clinical scores (Harris hip, WOMAC), hip flexion strength measurements, and magnetic resonance imaging findings.

Results

Compared with the contralateral non-operated side, the affected side showed no difference in hip flexion force in the supine upright neutral position and at 30° of flexion (205.4 N vs 221.7 N and 178.9 N vs. 192.1 N at 0° and 30° flexion, respectively). However, the affected side showed a significantly greater degree of fatty infiltration compared with the contralateral side (global fatty degeneration index 1.085 vs 0.784), predominantly within the psoas and iliacus muscles.

Conclusion

Severe displacement of the lesser trochanter (>?20 mm) in pertrochanteric fractures did not reduce hip flexion strength compared with the contralateral side. Displacement of the lesser trochanter in such cases can lead to fatty infiltration of the iliopsoas muscle unit. The amount of displacement of the lesser trochanter did not affect the degree of fatty infiltration.

Level of evidence

II.

     

The value of serum creatine kinase in predicting the risk of rhabdomyolysis-induced acute kidney injury: a systematic review and meta-analysis

Introduction

Identifying the potential effective factors of rhabdomyolysis-induced acute kidney injury (AKI) is of major importance for both treatment and logistic concerns. The present study aimed to evaluate the value of creatine kinase (CK) in predicting the risk of rhabdomyolysis-induced AKI through meta-analysis.

Methods

Two reviewers searched the electronic databases of Medline, EMBASE, Cochrane library, Scopus, and Google Scholar. Data regarding study design, patient characteristics, number of cases, mean and screening characteristics of CK, and final patient outcome were extracted from relevant studies. Pooled measures of standardized mean difference, OR, and diagnostic accuracy were calculated using STATA version 11.0.

Result

5997 non-redundant studies were found (143 potentially relevant). 27 articles met the inclusion criteria but 9 were excluded due to lack of data. The correlation between serum CK and AKI occurrence was stronger in traumatic cases (SMD = 1.34, 95 % CI = 1.25–1.42, I ² = 94 %; p < 0.001). This correlation was more prominent in crush-induced AKI (adjusted OR = 14.7, 95 % CI = 7.63–28.52, I ² = 0.0 %; p = 0.001). Area under the ROC curve of CK in predicting AKI occurrence was 0.75 (95 % CI = 0.71–0.79).

Conclusion

The results of this meta-analysis declared the significant role of rhabdomyolysis etiology (traumatic/non-traumatic) in predictive performance of CK. There was a significant correlation between mean CK level and risk of crush-induced AKI. The pooled OR of CK was considerable, but its screening performance characteristics were not desirable.

     

Efficacy of urinary midkine as a biomarker in patients with acute kidney injury

Background

The mortality and morbidity associated with acute kidney injury (AKI) remains high, despite advances in interventions. A multifunctional heparin-binding growth factor, midkine (MK), is involved in the pathogenesis of ischemic kidney injury. However, the clinical relevance of MK has not yet been elucidated. The present study investigated whether urinary MK can serve as a novel biomarker of AKI.

Methods

We initially compared the predictive value of MK with other urinary biomarkers, including N-acetyl-β-d-glucosaminidase (NAG), interleukin (IL)-18, and neutrophil gelatinase-associated lipocalin (NGAL), for the detection and differential diagnosis of established AKI (549 patients). Subsequently, the reliability of MK for the early detection of AKI was prospectively evaluated in 40 patients undergoing elective abdominal aortic aneurysm surgery. Urine samples were obtained at baseline, the period of aortic cross-clamping and declamping, the end of the surgery, and on post-operative day 1.

Results

The areas under the receiver operating characteristic curves for the diagnosis of AKI in various kidney diseases were 0.88, 0.70, 0.72, and 0.84 for MK, NAG, IL-18, and NGAL, respectively. When the optimal cutoff value of urinary MK was set at 11.5 pg/mL, the sensitivity and specificity were 0.87 and 0.85, respectively. In the second study, urinary MK peaked at the period of aortic declamping, about 1 h after cross-clamping in patients with AKI. Interestingly, the rise of MK in AKI patients was very precipitous compared with other biomarker candidates.

Conclusion

Urinary MK was prominent in its ability to detect AKI and may allow the start of preemptive medication.