Association of hypoalbuminemia with short-term and long-term mortality in patients undergoing continuous renal replacement therapy

Background

Hypoalbuminemia reflects several pathological conditions, including nutritional deficiencies and chronic inflammation. However, its relationship with short-term and long-term mortality in patients undergoing continuous renal replacement therapy (CRRT) remains unclear. The present study aimed to assess the effect of hypoalbuminemia on mortality in a large cohort of patients undergoing CRRT.

Methods

The study retrospectively reviewed 1,581 patients who underwent CRRT for the treatment of acute kidney injury from 2010 to 2016. The patients were categorized by tertiles of serum albumin levels at CRRT initiation. The odds ratios and hazard ratios for the risk of all-cause mortality were calculated before and after adjustment for multiple covariates.

Results

The mean albumin level was 2.7 ± 0.6 g/dL at CRRT initiation. During a median follow-up period of 14 days (maximum, 4 years), 1,040 patients (65.8%) died. The risk of overall mortality was higher in the first tertile group than in the third tertile group (hazard ratio, 1.9 [1.63-2.21]). When the mortality rate was stratified by timeframe, the risk was steadily higher in the first tertile group than in the third tertile group (odds ratios: 3.0 [2.34-3.87] for 2-week mortality, 2.7 [2.12-3.52] for 1-month mortality, 2.7 [2.08-3.53] for 6-month mortality, and 2.8 [2.11-3.62] for 1-year mortality). Additionally, the rates of intensive care unit mortality and in-hospital mortality were higher in the first tertile group than in the third tertile group.

Conclusion

The initial hypoalbuminemia was independently associated with short-term and long-term mortality in patients undergoing CRRT. Thus, the serum albumin level should be monitored during CRRT.

Expansion of Myeloid-Derived Suppressor Cells Correlates with Renal Progression in Type 2 Diabetic Nephropathy

Type 2 diabetic nephropathy (T2DN) progresses with an increasingly inflammatory milieu, wherein various immune cells are relevant. Herein, we investigated the levels of myeloid-derived suppressor cells (MDSCs) and their clinical implication in patients with T2DN. A total of 91 subjects (T2DN, n=80; healthy, n=11) were recruited and their PBMCs were used for flow cytometric analysis of polymorphonuclear (PMN-) and monocytic (M-) MDSCs, in addition to other immune cell subsets. The risk of renal progression was evaluated according to the quartiles of MDSC levels using the Cox model. The proportion of MDSCs in T2DN patients was higher than in healthy individuals (median, 6.7% vs. 2.5%). PMN-MDSCs accounted for 96% of MDSCs, and 78% of PMN-MDSCs expressed Lox-1. The expansion of PMN-MDSCs was not related to the stage of T2DN or other kidney disease parameters such as glomerular filtration rate and proteinuria. The production of ROS in PMN-MDSCs of patients was higher than in neutrophils of patients or in immune cells of healthy individuals, and this production was augmented under hyperglycemic conditions. The 4th quartile group of PMN-MDSCs had a higher risk of renal progression than the 1st quartile group, irrespective of adjusting for multiple clinical and laboratory variables. In conclusion, PMN-MDSCs are expanded in patients with T2DN, and may represent as an immunological biomarker of renal progression.

Apolipoprotein B is a risk factor for end-stage renal disease

Background

Apolipoprotein B (ApoB), a constituent of lipid particles, is known to increase the risk of cardiovascular diseases. However, the association between ApoB and end-stage renal disease (ESRD) remains to be resolved. Our objective was to determine whether the ApoB concentration has an association with the risk of ESRD.

Methods

Serum ApoB, ApoA1, conventional lipid parameters and lipid subfractions were analyzed in 9403 subjects. The hazard ratio (HR) for the risk of ESRD was calculated using tertiles of ApoB concentration.

Results

ESRD developed in 110 patients (1.2%) during 10 years of follow-up. Several lipid parameters were compared for their association with the risk of ESRD, of which ApoB was best and its relationship was also independent of other clinical parameters. Individuals in the second and third ApoB tertiles had a higher risk of ESRD than those in the first tertile, with HRs of 1.5 [95% confidence interval (CI) 0.89–2.61] and 2.6 (1.56–4.20), respectively. A high ApoB:ApoA1 ratio was associated with a higher risk of ESRD, but ApoA1 had no independent association. Even after adjusting the competing risk for all-cause death, high ApoB concentrations had an association with the risk of ESRD.

Conclusions

High ApoB concentration is associated with a higher risk of ESRD, despite adjustment for other lipid and clinical parameters. Accordingly, the monitoring of ApoB may be helpful for the prediction of ESRD.

Machine learning algorithm to predict mortality in patients undergoing continuous renal replacement therapy

Background

Previous scoring models such as the Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) scoring systems do not adequately predict mortality of patients undergoing continuous renal replacement therapy (CRRT) for severe acute kidney injury. Accordingly, the present study applies machine learning algorithms to improve prediction accuracy for this patient subset.

Methods

We randomly divided a total of 1571 adult patients who started CRRT for acute kidney injury into training (70%, n = 1094) and test (30%, n = 477) sets. The primary output consisted of the probability of mortality during admission to the intensive care unit (ICU) or hospital. We compared the area under the receiver operating characteristic curves (AUCs) of several machine learning algorithms with that of the APACHE II, SOFA, and the new abbreviated mortality scoring system for acute kidney injury with CRRT (MOSAIC model) results.

Results

For the ICU mortality, the random forest model showed the highest AUC (0.784 [0.744–0.825]), and the artificial neural network and extreme gradient boost models demonstrated the next best results (0.776 [0.735–0.818]). The AUC of the random forest model was higher than 0.611 (0.583–0.640), 0.677 (0.651–0.703), and 0.722 (0.677–0.767), as achieved by APACHE II, SOFA, and MOSAIC, respectively. The machine learning models also predicted in-hospital mortality better than APACHE II, SOFA, and MOSAIC.

Conclusion

Machine learning algorithms increase the accuracy of mortality prediction for patients undergoing CRRT for acute kidney injury compared with previous scoring models.

MEST-C pathological score and long-term outcomes of child and adult patients with Henoch-Schönlein purpura nephritis

BACKGROUND

Henoch-Schönlein purpura nephritis (HSPN), a small-vessel vasculitis, shares renal pathological features with immunoglobulin A nephropathy. Oxford classification of immunoglobulin A nephropathy pathology has been updated to the MEST-C score, but its application in HSPN remains unresolved.

METHODS

Two hundred and thirteen patients with biopsy-proven HSPN were retrieved from the Seoul National University Hospital between 2000 and 2017. Renal outcome risks (i.e., end-stage renal disease or doubling of serum creatinine) were evaluated according to MEST-C scores after stratification by age: 113 children aged < 18 years (9.2 ± 3.6 years) and 100 adults aged ≥18 years (38.6 ± 18.3 years). We pooled our data with four previous cohort studies in which MEST or MEST-C scores were described in detail.

RESULTS

Twenty-one child (19%) and 16 adult (16%) patients reached the renal outcome during the median follow-up periods of 12 years and 13 years, respectively (maximum 19 years). In children, M1 and T1/T2 scores revealed worse renal outcomes than did M0 and T0 scores, respectively, whereas the T score was the only factor related to worse outcomes in adult patients after adjusting for multiple clinical and laboratory variables. The pooled data showed that M1, S1, and T1/T2 in children and E1 and T1/T2 in adults were correlated with poorer renal outcomes than those of their counterpart scores.

CONCLUSIONS

The Oxford classification MEST-C scores can predict long-term renal outcomes in patients with HSPN.

Transplant outcomes in kidney recipients with lupus nephritis, and systematic review

Background

Despite improved survival of patients with lupus nephritis (LN), some require kidney transplantation because of progression to end-stage renal disease (ESRD). However, the transplant outcomes of these patients and other recipients have not been thoroughly compared.

Methods

In total, 1848 Korean kidney recipients who underwent transplantation from 1998 to 2017 at two tertiary referral centers were evaluated retrospectively. Among them, 28 recipients with LN, and 50 control recipients matched by age, sex, and donor type, were compared with respect to graft and patient survival. We pooled our data with 17 previous cohort studies in which the graft survival of recipients with LN was described in detail.

Results

During the median follow-up period of 9.5 years (maximum 21 years), graft failure (GF) occurred in 10.7% and 16.0% of LN and control recipients, respectively. No differences were found in the rates of GF and death-censored graft failure or patient survival between the two groups. The risks of acute T cell-mediated and antibody-mediated rejection were also similar between the two groups. The pooled analysis showed similar 1- and 5-year graft survival rates between LN and control recipients.

Conclusions

Kidney transplantation is an acceptable option in patients with concurrent LN and ESRD.

Glomerular hyperfiltration is associated with dementia: A nationwide population-based study

Background

Glomerular hyperfiltration may be a clinical phenotype of endothelial dysfunction. Endothelial dysfunction may cause vascular dementia through the deterioration of cerebral blood flow. We aimed to identify the risk of dementia in people with glomerular hyperfiltration.

Methods

Using the Korean National Health Information Database, we included subjects aged ≥45 years who underwent national health screening examinations between 2012 and 2015 and who had no previous history of end-stage renal disease or dementia (n = 2,244,582). The primary exposure was glomerular hyperfiltration. We divided the subjects into groups by sex and five-year age intervals and categorized each group into 8 intervals according to estimated glomerular filtration (eGFR). The subjects with an eGFR ≥95^th percentile in each group were defined as the hyperfiltration group. The outcomes were development of all types of dementia, Alzheimer's dementia and vascular dementia. Multivariable Cox proportional hazards models were used to analyze the hazard ratios (HRs) for outcomes.

Results

The Hyperfiltration group showed a higher risk for the development of all types of dementia [adjusted HR 1.09 (95% CI, 1.03–1.15)] and vascular dementia [adjusted HR 1.33 (95% CI, 1.14–1.55)] than the reference group. However, the association between hyperfiltration and Alzheimer's dementia was not statistically significant.

Conclusions

Glomerular hyperfiltration may be associated with dementia. In this respect, subjects with glomerular hyperfiltration should be monitored more closely for signs and symptoms of dementia.

Can a semi-quantitative method replace the current quantitative method for the annual screening of microalbuminuria in patients with diabetes? Diagnostic accuracy and cost-saving analysis considering the potential health burden

OBJECTIVES

Diabetes is a global epidemic, and the high cost of annually and quantitatively measuring urine albumin excretion using the turbidimetric immunoassay is challenging. We aimed to determine whether a semi-quantitative urinary albumin-creatinine ratio test could be used as a screening tool for microalbuminuria in diabetic patients.

METHODS

We assessed the diagnostic accuracy of the semi-quantitative method. The costs of false results in the semi-quantitative method were calculated based on the annual probability of disease progression analyzed through a systematic literature review and meta-analysis. The pooled long-term cost-saving effect of the semi-quantitative method compared with the quantitative test was assessed using a Markov model simulating a long-term clinical setting. Diagnostic accuracy and the cost-saving effect were also validated in an independent external cohort.

RESULTS

Compared with the quantitative test, the semi-quantitative method had sensitivities of 93.5% and 81.3% and specificities of 61.4% and 63.1% in the overall sample of diabetic patients (n = 1,881) and in diabetic patients with eGFR ≥60 ml/min/1.73 m2 and a negative dipstick test (n = 1,110), respectively. After adjusting for direct and indirect medical costs, including the risk of disease progression, which was adjusted by the meta-analyzed hazard ratio for clinical outcomes, it was determined that using the semi-quantitative method could save 439.4 USD per person for 10 years. Even after adjusting the result to the external validation cohort, 339.6 USD could be saved for one diabetic patient for 10 years.

CONCLUSIONS

The semi-quantitative method could be an appropriate screening tool for albuminuria in diabetic patients. Moreover, it can minimize the testing time and inconvenience and significantly reduce national health costs.

Cardiovascular risk of nonsteroidal anti-inflammatory drugs in dialysis patients: a nationwide population-based study

Background

Given the cardiovascular risk of nonsteroidal anti-inflammatory drugs (NSAIDs), it is essential to identify the relationship between NSAIDs and cardiovascular outcomes in dialysis patients who have elevated cardiovascular risk.

Methods

A case-crossover study was conducted to assess the association of NSAIDs with major adverse cardiac and cerebrovascular events (MACCEs) and mortality using the Korean Health Insurance dataset. The case period was defined as 1–30 days prior to the event date and the control periods were defined as 61–90 days and 91–120 days prior to the event date.

Results

There were 3433 and 8524 incident dialysis patients who experienced MACCEs and mortality, respectively, after exposure to NSAIDs within 120 days before each event. NSAIDs significantly increased the risk of MACCEs {adjusted odds ratio [aOR] 1.37 [95% confidence interval (CI) 1.26–1.50]} and mortality [aOR 1.29 (95% CI 1.22–1.36)]. Nonselective NSAIDs, but not selective cyclooxygenase-2 inhibitors, significantly increased the risk of MACCEs and mortality. However, the MACCE and mortality risk did not increase in a dose-dependent manner in the analysis according to the cumulative defined daily dosage of NSAIDs. The incidence of MACCEs in the case period tended to be more common in patients who had recent exposure to NSAIDs than in patients who did not have recent exposure to NSAIDs.

Conclusions

Clinicians should be particularly cautious when prescribing NSAIDs to dialysis patients considering the associations of NSAIDs with cardiovascular outcomes and mortality, which might occur independent of the dose and duration of exposure.

Krüppel-like factor 15 is a key suppressor of podocyte fibrosis under rotational force-driven pressure

Krüppel-like factor 15 (KLF15) is a well-known transcription factor associated with podocyte injury and fibrosis. Recently, hypertensive nephropathy was discovered to be closely related to podocyte injury and fibrosis. However, methods to stimulate hypertension in vitro are lacking. Here, we constructed an in vitro model mimicking hypertension using a rotational force device to identify the role of KLF15 in fibrosis due to mechanically induced hypertensive injury. First, we found that KLF15 expression was decreased in patients with hypertensive nephropathy. Then, an in vitro study of hypertension due to rotational force was conducted, and an increase in fibrosis markers and decrease in KLF15 levels were determined after application of 4 mmHg pressure in primary cultured human podocytes. KLF15 and tight junction protein levels increased with retinoic acid treatment. siRNA-mediated inhibition of KLF15 exacerbated pressure-induced fibrosis injury, and KLF15 expression after treatment with angiotensin II was similar to that observed after treatment with the blood pressure modeling device. Furthermore, the reduced KLF15 levels after mechanical pressure application were restored after the administration of an antihypertensive drug. KLF15 expression was also low in vivo. We confirmed the protective role of KLF15 in fibrosis using a mechanically induced in vitro model of hypertensive injury.

Altered Risk for Cardiovascular Events With Changes in the Metabolic Syndrome Status: A Nationwide Population-Based Study of Approximately 10 Million Persons

BACKGROUND

Population-scale evidence for the association between dynamic changes in metabolic syndrome (MetS) status and alterations in the risk for major adverse cardiovascular events (MACE) is lacking.

OBJECTIVE

To investigate whether recovery from or development of MetS in a population is associated with an altered risk for MACE.

DESIGN

Nationwide cohort study.

SETTING

An analysis based on the National Health Insurance Database of Korea.

PARTICIPANTS

A total of 27 161 051 persons who received national health screenings from 2009 to 2014 were screened. Those with a history of MACE were excluded. We determined the MetS status of 9 553 042 persons using the following harmonizing criteria: MetS-chronic (n = 1 486 485), MetS-developed (n = 587 088), MetS-recovery (n = 538 806), and MetS-free (n = 6 940 663).

MEASUREMENTS

The outcome was the occurrence of MACE, including acute myocardial infarction, revascularization, and acute ischemic stroke, identified from the claims database. The incidence rate ratios (IRRs) were calculated with adjustments for body mass index, comorbidity scores, previous metabolic variables, and other clinical or demographic variables.

RESULTS

At a median follow-up of 3.54 years, the MetS-recovery group (incidence rate, 4.55 per 1000 person-years) had a significantly lower MACE risk (adjusted IRR, 0.85 [95% CI, 0.83 to 0.87]) than that of the MetS-chronic group (incidence rate, 8.52 per 1000 person-years). The MetS-developed group (incidence rate, 6.05 per 1000 person-years) had a significantly higher MACE risk (adjusted IRR, 1.36 [CI, 1.33 to 1.39]) than that of the MetS-free group (incidence rate, 1.92 per 1000 person-years). Among the MetS components, change in hypertension was associated with the largest difference in MACE risk.

LIMITATION

Limited assessment of mortality and short follow-up.

CONCLUSION

Recovery from MetS was significantly associated with decreased risk for MACE, whereas development of MetS was associated with increased risk.

PRIMARY FUNDING SOURCE

Korea Healthcare Technology R&D Project, Ministry of Health and Welfare, Republic of Korea.

Kidney residency of VISTA-positive macrophages accelerates repair from ischemic injury

Tissue-resident macrophages have unique tissue-specific functions in maintaining homeostasis and resolving inflammation. However, the repair role and relevant molecules of kidney-resident macrophages after ischemic injury remain unresolved. To this end, mice without kidney-resident R1 macrophages but containing infiltrating monocyte-derived R2 macrophages were generated using differential cellular kinetics following clodronate liposome treatment. When ischemia-reperfusion injury was induced in these mice, late phase repair was reduced. Transcriptomic and flow cytometric analyses identified that V-domain Ig suppressor of T cell activation (VISTA), an inhibitory immune checkpoint molecule, was constitutively expressed in kidney-resident R1 macrophages, but not in other tissue-resident macrophages. Here, VISTA functioned as a scavenger of apoptotic cells and served as a checkpoint to control kidney-infiltrating T cells upon T cell receptor-mediated stimulation. Together these functions improved the repair process after ischemia-reperfusion injury. CD14⁺ CD33⁺ mononuclear phagocytes of human kidney also expressed VISTA, which has similar functions to the mouse counterpart. Thus, VISTA is upregulated in kidney macrophages in a tissue-dependent manner and plays a repair role during ischemic injury.

Effect of Liver Cirrhosis on the Outcomes of Peritoneal Dialysis

Background:Peritoneal dialysis (PD) has become an increasingly important treatment modality for end-stage renal disease. However, application of PD in patients with liver cirrhosis (LC) and subsequent outcomes have not been thoroughly evaluated.Methods:A total of 1,366 patients (≥ 18 years old) who started PD at 4 tertiary referral centers between January 2000 and December 2015 were initially reviewed. Among them, 45 patients with LC were finally analyzed (LC-PD). Using the multivariate Cox hazard ratio (HR) model, outcomes such as technique failure, infection, and mortality in patients with LC-PD were compared with those in non-LC-PD patients (non-LC-PD) or patients with LC who received hemodialysis (LC-HD). All of the patients were selected by 1:1 matching of age, sex, catheter insertion date, and diabetes mellitus.Results:During the mean follow-up duration of 43 ± 35.8 months, 12 patients with LC-PD experienced technique failure, and this rate was similar to that of non-LC-PD patients. In evaluating infection episodes, the most common causes for peritonitis and exit-site infection were Escherichia coli (5.8%) and Staphylococcus aureus (19.3%), respectively; these event rates of LC-PD did not differ from those of non-LC-PD. The all-cause mortality rate of the LC-PD group was not different from that of the non-LC-PD and LC-HD groups.Conclusion:Dialysis outcomes such as technique failure, infection, and mortality are not affected by the presence of LC. Accordingly, PD therapy is a good option in patients with LC.

Development of a new mortality scoring system for acute kidney injury with continuous renal replacement therapy

AIM

On the basis of the worst outcomes of patients undergoing continuous renal replacement therapy (CRRT) in intensive care unit, previously developed mortality prediction model, Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) needs to be modified.

METHODS

A total of 828 patients who underwent CRRT were recruited. Mortality prediction model was developed for the prediction of death within 7 days after starting the CRRT. Based on regression analysis, modified scores were assigned to each variable which were originally used in the APACHE II and SOFA scoring models. Additionally, a new abbreviated Mortality Scoring system for AKI with CRRT (MOSAIC) was developed after stepwise selection analysis.

RESULTS

We used all the variables included in the APACHE II and SOFA scoring models. The prediction powers indicated by C-statistics were 0.686 and 0.683 for 7-day mortality by the APACHE II and SOFA systems, respectively. After modification of these models, the prediction powers increased up to 0.752 for the APACHE II and 0.724 for the SOFA systems. Using multivariate analysis, seven significant variables were selected in the MOSAIC model wherein its C-statistic value was 0.772. These models also showed good performance with 0.720, 0.734 and 0.773 of C-statistics in the modified APACHE II, modified SOFA and MOSAIC scoring models in the external validation cohort (n = 497).

CONCLUSION

The modified APACHE II/SOFA and newly developed MOSAIC models could be more useful tool for predicting mortality for patients receiving CRRT.

Hyperphosphatemia and risks of acute kidney injury, end-stage renal disease, and mortality in hospitalized patients

BACKGROUND

Hyperphosphatemia is associated with vascular calcification and bone mineral disorders and is a major concern among patients with chronic kidney disease (CKD). However, the relationship between hyperphosphatemia and renal outcome in non-CKD patients has not been studied. Furthermore, the clinical implications of hyperphosphatemia in relation to the risks of acute kidney injury (AKI), end-stage renal disease (ESRD), and mortality after hospitalization remain unresolved.

METHODS

A total of 20,686 patients (aged ≥18 years) admitted to Seoul National University Bundang Hospital from January 2013 to December 2013 were retrospectively reviewed. Patients were divided into quartiles according to serum phosphorus level at the time of admission. The odds ratios (ORs) for AKI and hazard ratios (HRs) for ESRD and all-cause mortality were calculated after adjustment of multiple covariates.

RESULTS

AKI developed in 2319 patients (11.2%), with higher ORs for patients in the third and fourth quartiles (1.4 [1.24-1.68] and 2.8 [2.44-3.22], respectively) compared with the first quartile group. During a median follow-up period of 4.0 years, 183 patients (0.88%) developed ESRD and 3675 patients (17.8%) died. Patients in the fourth quartile had higher risks of ESRD and mortality than patients in the first quartile (HRs, 2.3 [1.46-3.75] and 1.4 [1.22-1.49], respectively). These trends remained consistent in patients with an estimated glomerular filtration rate > 60 ml/min/1.73 m².

CONCLUSIONS

Hyperphosphatemia is related to the risks of AKI, ESRD, and mortality, and it may therefore be necessary to monitor serum phosphorus level in hospitalized patients, irrespective of kidney function.

Impacts of GFP-FoxP3+ regulatory T cells on lupus hallmarks differ by genetic background and type of GFP knock-in

FoxP3 reporter mice expressing green fluorescence protein (GFP) have been used as a very convenient tool to investigate the impact of regulatory T (Treg) cells on pathogenesis in autoimmune diseases. Here, we found that GFP-FoxP3⁺ knock-in (KI) mice showed alterations in the production of anti-nuclear autoantibodies (ANAs) and nephritis with different extent, depending on the presence or absence of lupus susceptibility gene locus 1 (Sle1) and KI method: contrasting with B6.Sle1.fGFP-FoxP3 mice, expressing GFP via N-terminal insertion, B6.Sle1.iGFP-FoxP3, expressing GFP via bicistronic internal ribosome entry site-driven promotion, exhibited significantly lower penetrance of serum ANA, comparing to control B6.Sle1 mice. Moreover, B6.Sle1.GFP-FoxP3⁺ mice reduced the Sle1-induced splenomegaly and B-cell expansion independently of the KI method employed, mainly by reducing the numbers of transitional 1 (T1) B cells and CD21^-CD23^- B cells, including plasmablasts and plasma cells. The absolute numbers of both splenic CD4⁺ T cells and Treg cells from B6.Sle1.GFP-FoxP3 KI mice were significantly reduced but their proportion was not changed, compared to B6.Sle1 mice. Although the glomerular basement membranes were thickened in both B6.Sle1 and B6.Sle1.iGFP-FoxP3 mice, they were thinner in B6.Sle1.fGFP-FoxP3 mice. The latter mice expressed more nephrophilic autoantibodies and deposited more complement component 3 in glomeruli compared to B6.iGFP-FoxP3 mice. FoxP3⁺ Treg cells may modulate B-cell tolerance in lupus-prone B6.Sle1 mice, presumably by modulating pathogenic, nephrophilic autoantibody production and nephritis.

Impact of Pneumocystis jirovecii pneumonia on kidney transplant outcome

Backgrounds

Pneumocystis jirovecii pneumonia (PCP) remains an important cause of morbidity and mortality in kidney transplant recipients. While the acute phase toxicity in patients with PCP is well-characterized, there is a lack of data on the effects of PCP on long-term graft outcome.

Method

This retrospective observational study analyzed 1502 adult patients who underwent kidney transplantation at Seoul National University Hospital between 2000 and 2017. After a propensity score matching was performed, the graft and survival outcomes were compared between PCP-negative and PCP-positive groups.

Results

A total of 68 patients (4.5%) developed PCP after transplantation. The multivariable Cox analysis showed that positivity for cytomegalovirus and lack of initial oral antibiotic prophylaxis were risk factors of post-transplant PCP. The PCP-positive group had higher hazard ratios of graft failure [adjusted hazard ratio (HR), 3.1 (1.14–8.26); P = 0.027] and mortality [adjusted HR, 11.0 (3.68–32.80); P < 0.001] than the PCP-negative group. However, the PCP event was not related with subsequent development of de novo donor-specific antibodies or pathologic findings, such as T-cell or antibody mediated rejection and interstitial fibrosis and tubular atrophy.

Conclusions

PCP is a risk factor of long-term graft failure and mortality, irrespective of rejection. Accordingly, appropriate prophylaxis and treatment is needed to avoid adverse transplant outcomes of PCP.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1407-x) contains supplementary material, which is available to authorized users.

Hyperuricemia is associated with acute kidney injury and all-cause mortality in hospitalized patients

AIM

Hyperuricemia is a risk factor for high morbidity and mortality in several diseases. However, the relationship between uric acid (UA) and the risk of acute kidney injury (AKI) and mortality remain unresolved in hospitalized patients.

METHODS

Data from 18 444 hospitalized patients were retrospectively reviewed. The odds ratio (OR) for AKI and the hazard ratio (HR) for all-cause mortality were calculated based on the UA quartiles after adjustment for multiple variables. All analyses were performed after stratification by sex.

RESULTS

The fourth quartile group (male, UA > 6.7 mg/dL; female, UA > 5.4 mg/dL) showed a higher risk of AKI compared with the first quartile group (male, UA < 4.5 mg/dL; female, UA < 3.6 mg/dL), with the following OR: 3.2 (2.55-4.10) in males (P < 0.001); and 3.1 (2.40-4.19) in females (P < 0.001). There were more patients who did not recover from AKI in the fourth quartile compared with the first quartile, with the following OR: 2.0 (1.32-3.04) in males (P = 0.001) and 2.4 (1.43-3.96) in females (P = 0.001). The fourth quartile group had a higher risk of all-cause mortality compared with the first quartile group, with the following HR: 1.4 (1.20-1.58) in males (P < 0.001) and 1.2 (1.03-1.46) in females (P = 0.019). The in-hospital mortality risk was also higher in the fourth quartile compared with the first quartile, which was significant only in males (OR, 2.1 (1.33-3.31) (P = 0.002)).

CONCLUSION

Hyperuricemia increases the risks of AKI and all-cause mortality in hospitalized patients.

Development of model to predict end-stage renal disease after coronary artery bypass grafting: The ACHE score

Because end-stage renal disease (ESRD) increases the risks of morbidity and mortality, early detection and prevention of ESRD is a critical issue in clinical practice. However, no ESRD-prediction models have been developed or validated in patients undergoing coronary artery bypass grafting (CABG).This is a retrospective multicenter cohort study, recruited between January 2004 and December 2015. A cohort of 3089 patients undergoing CABG in two tertiary referral centers was analyzed to derive a risk-prediction model. The model was developed using Cox proportional hazard analyses, and its performance was assessed using C-statistics. The model was externally validated in an independent cohort of 279 patients.During the median follow-up of 6 years (maximum 13 years), ESRD occurred in 60 patients (2.0%). Through stepwise selection multivariate analyses, the following three variables were finally included in the ESRD-prediction model: postoperative Acute kidney injury, underlying Chronic kidney disease, and the number of antiHypertensive drugs (ACHE score). This model showed good performance in predicting ESRD with the following C-statistics: 0.89 (95% confidence interval [CI] 0.84-0.94) in the development cohort and 0.82 (95% CI 0.60-1.00) in the external validation cohort.The present ESRD-prediction model may be applicable to patients undergoing CABG, with the advantage of simplicity and preciseness.

The association of tumor necrosis factor superfamily 13 with recurrence of immunoglobulin A nephropathy in living related kidney transplantation

Background

An increasing amount of evidence has demonstrated an association between an increase in the level of tumor necrosis factor superfamily 13 (TNFSF13) and immunoglobulin A nephropathy (IgAN) progression. We aimed to evaluate if the level of pre-transplant serum TNFSF13 is predictive of IgAN recurrence after kidney transplantation.

Methods

This analysis was based on the clinical and laboratory data of 69 patients with IgAN who underwent first kidney transplantation with no evidence of mesangial IgA deposits in zero-time transplantation biopsy. We measured pre-transplant serum TNFSF13, total IgA, and galactose-deficient IgA1 levels.

Results

The recurrence rate of IgAN over a median follow-up duration of 5.1 years was 15.9% (11/69 patients), with a mean time to the first recurrence of 1.7 years. The high pre-transplant TNFSF13 level was associated with IgAN recurrence after kidney transplantation among patients who received a graft from a living related donor.

Conclusions

This study highlights association of TNFSF13 levels in recurrent IgAN patients who undergo living related donor transplantation. Further research is needed to clarify mechanisms by which TNFSF13 affects the recurrence of IgA nephropathy.

The level of intracellular tacrolimus in T cell is affected by CD44+ABCB1+activities triggered by inflammation

Rejection is an important issue in kidney transplant. Although with adequate trough level of tacrolimus, acute rejection occurs, and we are focused on these cases. We hypothesized that the lower concentration of tacrolimus in the peripheral blood mononuclear cell would be a cause of rejection; in this regard, we describe ABCB1, which regulates intracellular concentration of tacrolimus. The effect of inflammation on the intracellular concentration of tacrolimus was evaluated, as was the association between that concentration and ABCB1 and CD44 activities. Seven kidney recipients experiencing acute rejection were prospectively enrolled. Both the whole blood concentration of tacrolimus and intracellular concentration of tacrolimus were measured at the time of enrollment and after stabilization. A human T lymphoblastoid cell line (Jurkat T cell) was treated with various concentrations of tacrolimus for 21 h and then stimulated for 3 h. The levels of mRNA interleukin-2, interleukin-8, and interferon-γ decreased dose dependently by tacrolimus. Furthermore, a fluorescence-activated cell sorter was used to count cells expressing CD44 and ABCB1; changes in intracellular concentration of tacrolimus were explored after tacrolimus treatment and stimulation. Also, B6 splenocytes were tested in the same manner as previous Jurkat T cell experiments. The tacrolimus ratio of three patients was lower at the time of acute rejection than when patients were stabilized. In vitro, the intracellular concentration of tacrolimus decreased after stimulation. Under the same conditions, CD44+ABCB1+cells increased in proportion on tacrolimus treatment and stimulation. This work supports the hypothesis that inflammation reduces the intracellular tacrolimus level, possibly via drug efflux mediated by CD44+ABCB1+and inflammation could lead to acute rejection.

Three-year income trends in Korean adults commencing haemodialysis: A prospective cohort

AIM

This study aimed to explore the trends in individual income and to estimate the change in average monthly income for patients undergoing haemodialysis therapy.

METHODS

The main data source was the Clinical Research Center (CRC) for End-Stage Renal Disease in Korea. In addition to the cohort data, a survey was conducted to capture personal income for 3 years. To estimate the change in monthly income over time using repeated measures, a random coefficient model using penalized quasi-likelihood methods based on restricted or residual maximum likelihood estimation was used.

RESULTS

During the 3-year study period, 138 subjects aged 20 and over who answered the question about pre-dialysis income were traced and analyzed. The median value of monthly income was $US564.4 in the 1^st year, $470.4 in the 2^nd year, and $733.8 in the 3^rd year, representing a 70%, 75%, and 61% decrease compared to pre-dialysis income ($1881.5), respectively. By using mixed analysis, we found that monthly income change was $1283 (95% CI, -1621.5, -945.1), $1182 USD (95% CI, -1540.8, -823.1), and $1041 (95% CI, -1457.6, -623.6) in the 1^st , 2^nd , and 3^rd year, respectively, compared to pre-dialysis income after controlling for other covariates. Women and less educated patients had a relatively higher reduction of income, despite the low starting point.

CONCLUSIONS

The monthly income of dialysis patients reduced substantially over the study period, especially at the time of the first survey. Considering the social security system, haemodialysis patients face significant personal financial burdens due to their ESRD unrelated to the direct costs of dialysis treatment.

Differential Signature of Obesity in the Relationship with Acute Kidney Injury and Mortality after Coronary Artery Bypass Grafting

BACKGROUND

Obesity is related to several comorbidities and mortality, but its relationship with acute kidney injury (AKI) and long-term mortality remain undetermined in patients undergoing coronary artery bypass grafting.

METHODS

Data from 3,018 patients (age ≥ 18 years) who underwent coronary artery bypass graft surgery from two tertiary referral centers were retrospectively reviewed between 2004 and 2015. Obesity was defined using the body mass index, according to the World Health Organization's recommendation. The odds and hazard ratios in post-surgical, AKI, and all-cause mortality were calculated after adjustment for multiple covariates. Patients were followed for 90 ± 40.9 months (maximum: 13 years).

RESULTS

Among the cohort, 37.4%, 2.4%, 21.1%, 35.1%, and 4.0% of patients were classified as normal weight, underweight, overweight-at-risk, obese I, and obese II, respectively. Post-surgical AKI developed in 799 patients (26.5%). Patients in the obese groups (overweight-at-risk to obese II) had a higher risk of AKI than did those in the normal-weight group. During the follow-up period, 787 patients (26.1%) died. Underweight patients had a higher risk of mortality than did normal-weight patients, whereas overweight-at-risk, obese I, and obese II patients showed better survival rates.

CONCLUSION

After coronary artery bypass graft surgery, obese patients encountered a high risk of AKI, and underweight patients exhibited a low chance of survival. Awareness of both obese and underweight statuses should be raised in these patients.

Systolic and diastolic dysfunction affects kidney outcomes in hospitalized patients

Backgrounds

Knowledge on cross-talk between the heart and kidney has been established by basic and clinical research. Nevertheless, the effects of systolic and diastolic heart dysfunctions on the development of acute kidney injury (AKI) and end-stage renal disease (ESRD) remain unresolved in hospitalized patients.

Methods

A total of 1327 hospitalized patients who had baseline transthoracic echocardiography performed were retrospectively analyzed. Patients were categorized by the quartiles of ejection fraction (EF) and the ratio of the early transmitral blood flow velocity to early diastolic velocity of the mitral annulus (E/e’). The odds ratios (ORs) for AKI and the hazard ratios (HRs) for ESRD were calculated after adjustment of multiple covariates.

Results

During hospital admission, AKI occurred in 210 (15.8%) patients. The lowest quartile of EF was associated with a risk of AKI (OR, 1.60 [1.07–2.41]) and the highest quartile of E/e’ was associated with a risk of AKI (OR, 1.90 [1.26–2.41]). When two echocardiographic parameters were combined, patients with a low EF (first to second quartiles) and high E/e’ (fourth quartile) showed the highest OR for AKI (OR, 2.27 [1.49–3.45]) compared with the counterpart patients. When the risk of ESRD was evaluated, E/e’, but not EF, was a significant parameter of high risk (fourth vs. first quartiles: HR, 4.13 [1.17–14.64]).

Conclusions

Baseline systolic and diastolic dysfunction is related to subsequent risks of AKI and ESRD in hospitalized patients. Monitoring of these parameters may be a useful strategy to predict the risk of these adverse events in the kidney.

Loss of KLF15 accelerates chronic podocyte injury

Krüppel‑like factor 15 (KLF15), also known as kidney‑enriched transcription factor, is known to participate in podocyte differentiation. However, the role of KLF15 in chronic podocyte injury remains incompletely understood, particularly in proteinuric disease models. In the present study, the 5/6 nephrectomy mouse model was used to induce chronic podocyte injury. Human primary podocytes were isolated by flow cytometry and cultured to emulate the injury process in an in vitro system. Biopsied kidney tissue samples were obtained from patients with primary membranous nephropathy or diabetic nephropathy in order to analyze the relationship between glomerular KLF15 expression and subsequent outcomes. When 5/6 nephrectomy was predisposed to progressive kidney damage, fibrosis markers increased, while podocyte KLF15 expression decreased. In addition, increased fibrosis marker expression in human primary podocytes following treatment with transforming growth factor‑β was aggravated by the knockdown of KLF15. These trends were reversed after cultured podocytes were treated with cyclosporine. When patients were grouped according to KLF15 expression levels in kidney tissue, the low expression groups were demonstrated to have worse renal outcomes, such as non‑remission of disease and end‑stage renal disease. In conclusion, the present findings revealed that low expression of KLF15 was associated with chronic podocyte injury.

Weight loss has an additive effect on the proteinuria reduction of angiotensin II receptor blockers in hypertensive patients with chronic kidney disease

Background

Weight reduction is a lifestyle intervention that has been introduced for prevention and management of chronic kidney disease (CKD). We investigate the additive anti-proteinuric effect of weight reduction on the usage of angiotensin II receptor blockers (ARBs) and its potential mechanisms in hypertensive CKD patients.

Methods

This study is a subanalysis of data from an open-label, randomized, controlled clinical trial. Among the 235 participants, 227 were assigned to subgroups according to changes in body weight.

Results

Fifty-eight participants (25.6%) were assigned to group 1 (≥1.5% decrease in body weight after 16 weeks), 32 participants (14.1%) were assigned to group 2 (1.5–0.1% decrease in body weight), and 136 participants (59.9%) were assigned to group 3 (≥ 0.0% increase in body weight). Characteristics at enrollment were not different among the three groups, but mean differences in weight and percent changes in urinary sodium excretion over the period were statistically different (P < 0.001 and P = 0.017). Over the study period, unintentional weight loss independently increased the probability of reduced albuminuria (group 1, relative risk 6.234, 95% confidence interval 1.913–20.315, P = 0.002). Among urinary cytokines, only podocalyxin level decreased significantly in participants who lost weight (P = 0.013).

Conclusion

We observed that weight loss had an additive effect on the anti-proteinuric effects of ARBs in nondiabetic hypertensive CKD patients, although it was minimal. An additive effect was shown in both obese and non-obese participants, and its possible mechanism is related to reduction of podocyte damage.

BAFF and APRIL expression as an autoimmune signature of membranous nephropathy

Background

Based on the fact that B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) have a regulatory role in B cell biology, excessive levels of these cytokines can promote autoimmune pathogenesis. However, the expression and implication remain unresolved in cases of membranous nephropathy (MN).

Results

The plasma BAFF levels of the primary MN patients were higher than those of healthy controls but lower than those of secondary MN patients, whereas the APRIL levels were similar between the MN patients and healthy controls. The BAFF levels were higher in relapse cases, whereas the APRIL levels were higher in the patients who did not experience remission compared with the counterpart patients. The ectopic expression of BAFF and APRIL was observed in the glomeruli or circulating B cells of MN patients, and this high expression trend was similar to that of lupus patients.

Conclusions

Expression profile of BAFF and APRIL in MN is similar to that of other autoimmune disease, which affects the kidney outcomes.

Methods

Plasma BAFF and APRIL levels were measured upon kidney biopsy in patients with primary (n = 89) and secondary MN (n = 13), and the results were compared with the levels in healthy controls (n = 111). The kidney outcomes (e.g., remission and relapse) were traced for the median of 3 years. Aberrant expression of the cytokines was evaluated in the kidney and circulating B cells using immunohistochemistry and flow cytometry analyses, respectively.

Streamlined Liner of the Pharynx Airway: Randomised Comparison of Size Selection Strategies with Regard to Patient Height versus Thyroid Cartilage Width

Introduction

Streamlined Liner of the Pharynx Airway (SLIPA) is a disposable supraglottic airway. There are two strategies to select the size of SLIPA: by height and width of thyroid cartilage. This study compared the utility of the two strategies in selecting the optimal size.

Methods

One hundred forty-two patients were randomly divided into two groups with size selection by height (H) and the maximal width of the thyroid cartilage (T). The SLIPA size was selected by height in group H, and by the width of thyroid cartilage in group T. After inserting SLIPA, the investigator made note of the oropharyngeal leakage pressure (OLP) and the degree of insertion difficulty. We set the OLP as a primary outcome. In cases of an OLP <15 cmH2O, the investigator manipulated the apparatus to try to reposition it. If air still leaked, another attempt was made using a SLIPA one size larger until an OLP >15 cmH2O was achieved in up to three attempts. After insertion, the investigator measured the inspiratory and expiratory tidal volume. Post-operatively, the presence of blood or regurgitated fluid on the device was evaluated.

Results

OLP for group T was higher than that of group H (p=0.009). The need for manipulation and the leak fraction was higher in group H than in group T (p=0.008 and 0.034, respectively). The degree of insertion difficulty, number of trials and incidence of blood and regurgitated fluid on the device were similar between the two groups.

Conclusions

Both the width and height of thyroid cartilage can be used for selecting the optimal SLIPA size. (Hong Kong j.emerg.med. 2015;22:303-311)

Heart rate is associated with mortality in patients undergoing continuous renal replacement therapy

BACKGROUND

Heart rate (HR) is an essential vital sign based on the finding that HR beyond its normal range is associated with several conditions or diseases, including high mortality in several clinical settings. Nevertheless, the clinical implications of HR remain unresolved in patients undergoing continuous renal replacement therapy (CRRT).

METHODS

This retrospective cohort study included 828 patients who underwent CRRT due to acute kidney injury between 2010 and 2014. HR and other baseline parameters at the time of CRRT initiation were retrieved. The odds ratio (OR) of 30-day mortality was calculated using a multivariate logistic model.

RESULTS

CRRT significantly lowered the HR of patients such that the pre- and post-CRRT HRs (average 6 hours) were 107 beats/min and 103 beats/min, respectively (P < 0.001). When we explored the relationship with 30-day mortality, only HR at the time of CRRT initiation, but not pre- or post-CRRT HR, had a significant relationship with mortality outcome. Based on this result, we divided patients into quartiles of HR at the time of CRRT initiation. Mortality OR in the 4th quartile HR group was 2.6 (1.78-3.92) compared with the 1st quartile HR group. This relationship remained consistent despite adjusting for 28 baseline covariates: OR, 1.7 (1.09-2.76); P = 0.020. However, HR was not associated with the weaning rate from CRRT.

CONCLUSION

High HR at the time of CRRT initiation is subsequently related with high mortality. These results can be a basis for a future predictive model of CRRT-related mortality.

Risk of Stroke in Elderly Dialysis Patients

Despite the current knowledge about the risk of stroke and its related factors in general population, this issue in elderly patients receiving dialysis remains unresolved. Firstly, to compare the risk of stroke between hemodialysis (HD) and peritoneal dialysis (PD), data on 13,065 incident dialysis patients (aged ≥ 65 years; 10,675 in HD and 2,390 in PD) were retrieved from the Korean Health Insurance dataset. Secondly, to identify the risk factors of stroke amongst various clinical and laboratory parameters in HD, 980 elderly patients were retrospectively analyzed using an independent prospective cohort from 31 dialysis centers. For a mean duration of 1.8 years (maximum of 5 years), the risk of all cardiovascular diseases (ischemic heart disease and stroke) did not differ between HD and PD. However, when analyses were conducted separately by subtype, the risk of stroke, not ischemic heart disease, was significantly higher in HD patients than in PD patients. When the risk factors of stroke were probed after HD for a mean duration of 2.6 years (maximum of 7 years), the absolute dependence on social support, a previous history of cardiovascular disease, high levels of low-density lipoprotein cholesterol, and the use of a high number of anti-hypertensive drugs were identified as being significant. Based on the discrepancy of stroke risk between modalities and the HD-tailored risk factors of stroke, the monitoring and management of these factors may be a key strategy to reduce the risk of stroke in elderly patients receiving dialysis.

IgH isotype-specific B cell receptor dosage regulates B cell fate

Immunoglobulin heavy chain (IgH) isotypes (e.g. IgM, IgG and IgE) are generated as secreted/soluble antibodies (sIg) or as membrane-bound (mIg) B cell receptors (BCR) through alternative RNA splicing. IgH isotype dictates soluble antibody function, but how mIg isotype influences B cell behavior is unclear. We examined IgH isotype-specific BCR function by engineering polyclonal Ighγ1/γ1 and Ighɛ/ɛ mice, which initially produce IgG1 or IgE from their respective native genomic configurations. Transcripts producing IgM, IgG1, and IgE are produced in an alternative splice form bias hierarchy, where mIgμ&gt;mIgγ1&gt;mIgɛ—influencing respective BCR densities and fitness for populating the periphery—a pattern replicated in activated and memory B cells from wild-type mice. Restrained B cell development from Ighγ1/γ1 and Ighɛ/ɛ mice was proportional to sIg/mIg ratios, and was rescued by enforced expression of the respective mIgs. In addition, enhanced BCR signaling by way of PTEN deletion in IgE B cells generated functional IgE memory responses from IgE memory B cells themselves, which are normally absent under normal conditions, indicating that weak signal strength normally restrains IgE responses. Thus, IgH isotype-specific mIg dosage regulates B cell fate by influencing quantitative baseline BCR signal strength.

Usefulness of Preoperative Echocardiography to Predict Acute Kidney Injury and Long-Term Mortality After Coronary Artery Bypass Grafting

Acute kidney injury (AKI) is a common complication in patients undergoing coronary artery bypass grafting (CABG), which is associated with significant morbidity and mortality. This study identified echocardiographic predictors of AKI and determined whether these predictors were related to long-term mortality in CABG. This retrospective cohort study included 1,300 patients who underwent echocardiography before CABG at 2 tertiary referral centers from 2004 to 2010. The best echocardiographic predictor of AKI was determined using multivariate and stepwise selection methods. Patients were followed for 72 ± 28.8 months (maximum 11 years) for all-cause mortality. We measured the adjusted odds ratio and hazard ratio for AKI and all-cause mortality, respectively, according to the chosen parameter. E/e' was the best predictor of AKI among echocardiographic parameters. The high E/e' group (>15) exhibited a greater odds ratio for AKI (2.2 [1.51 to 3.27]) than the low E/e' group (<8). The high E/e' group required a longer hospital stay (16 days [12 to 23 days]) than the low E/e' group (14 days [11 to 17 days]). There were 272 deaths (21%) during follow-up. The high E/e' group exhibited a greater hazard ratio for long-term mortality (1.9 [1.34 to 2.76]) than the low E/e' group, and this difference remained statistically significant regardless of the occurrence of AKI and the size of the ejection fraction volume. E/e' in preoperative echocardiography is the best predictor of AKI and long-term mortality in patients undergoing CABG.

Metabolic Acidosis and Long-Term Clinical Outcomes in Kidney Transplant Recipients

Metabolic acidosis (MA), indicated by low serum total CO₂ (TCO₂) concentration, is a risk factor for mortality and progressive renal dysfunction in CKD. However, the long-term effects of MA on kidney transplant recipients (KTRs) are unclear. We conducted a multicenter retrospective cohort study of 2318 adult KTRs, from January 1, 1997 to March 31, 2015, to evaluate the prevalence of MA and the relationships between TCO₂ concentration and clinical outcomes. The prevalence of low TCO₂ concentration (<22 mmol/L) began to increase in KTRs with eGFR<60 ml/min per 1.73 m² and ranged from approximately 30% to 70% in KTRs with eGFR<30 ml/min per 1.73 m² Multivariable Cox proportional hazards models revealed that low TCO₂ concentration 3 months after transplant associated with increased risk of graft loss (hazard ratio [HR], 1.74%; 95% confidence interval [95% CI], 1.26 to 2.42) and death-censored graft failure (DCGF) (HR, 1.66; 95% CI, 1.14 to 2.42). Cox regression models using time-varying TCO₂ concentration additionally demonstrated significant associations between low TCO₂ concentration and graft loss (HR, 3.48; 95% CI, 2.47 to 4.90), mortality (HR, 3.16; 95% CI, 1.77 to 5.62), and DCGF (HR, 3.17; 95% CI, 2.12 to 4.73). Marginal structural Cox models adjusted for time-varying eGFR further verified significant hazards of low TCO₂ concentration for graft loss, mortality, and DCGF. In conclusion, MA was frequent in KTRs despite relatively preserved renal function and may be a significant risk factor for graft failure and patient mortality, even after adjusting for eGFR.

Posttransplant Hyponatremia Predicts Graft Failure and Mortality in Kidney Transplantation Recipients: A Multicenter Cohort Study in Korea

Although hyponatremia is related to poorer outcomes in several clinical settings, its significance remains unresolved in kidney transplantation. Data on 1,786 patients who received kidney transplantations between January 2000 and December 2011 were analyzed. The patients were divided into two groups according to the corrected sodium values for serum glucose 3 months after their transplantations (<135 mmol/L vs. ≥135 mmol/L). Subsequently, the hazard ratios (HRs) for biopsy-proven acute rejection, graft failure, and all-cause mortality were calculated after adjustments for several immunological and non-immunological covariates. 4.0% of patients had hyponatremia. Patients with hyponatremia had higher risks for graft failure and all-cause mortality than did the counterpart normonatremia group; the adjusted HRs for graft failure and mortality were 3.21 (1.47-6.99) and 3.03 (1.21-7.54), respectively. These relationships remained consistent irrespective of heart function. However, hyponatremia was not associated with the risk of acute rejection. The present study addressed the association between hyponatremia and graft and patient outcomes in kidney transplant recipients. Based on the study results, our recommendation is to monitor serum sodium levels after kidney transplantations.

Monitoring the Intracellular Tacrolimus Concentration in Kidney Transplant Recipients with Stable Graft Function

Although monitoring the intracellular concentration of immunosuppressive agents may be a promising approach to individualizing the therapy after organ transplantation, additional studies on this issue are needed prior to its clinical approval. We investigated the relationship between intracellular and whole blood concentrations of tacrolimus (IC-TAC and WB-TAC, respectively), the factors affecting this relationship, and the risk of rejection based upon IC-TAC in stable kidney recipients. Both IC-TAC and WB-TAC were measured simultaneously in 213 kidney recipients with stable graft function using LC-MS/MS. The tacrolimus ratio was defined as IC-TAC per WB-TAC. The genetic polymorphism of ABCB1 gene and flow cytometric analyses were conducted to probe the correlation between tacrolimus concentrations and the immunoreactivity status as a potential risk of rejection, respectively. The correlation between IC-TAC and WB-TAC was relatively linear (r = 0.67; P<0.001). The factors affecting the tacrolimus ratio were sex, hematocrit, and the transplant duration, as follows: a high tacrolimus ratio was noted in female patients, patients with a low hematocrit, and patients with a short transplant period. However, the tacrolimus ratio did not reflect the prior clinical outcomes (e.g., rejection) or the genetic polymorphism of ABCB1. After stimulation with phorbol-12-myristate 13-acetate and ionomycin, the proportion of T cells producing interferon-gamma or interleukin-2 was higher in the low-IC-TAC group than in the high-IC-TAC group. Further studies are required to evaluate the value of the intracellular tacrolimus concentrations in several clinical settings, such as rejection, infection, and drug toxicity.

The Role of TNF Superfamily Member 13 in the Progression of IgA Nephropathy

TNF superfamily member 13 (TNFSF13) has been identified as a susceptibility gene for IgA nephropathy in recent genetic studies. However, the role of TNFSF13 in the progression of IgA nephropathy remains unresolved. We evaluated two genetic polymorphisms (rs11552708 and rs3803800) and plasma levels of TNFSF13 in 637 patients with IgA nephropathy, and determined the risk of ESRD according to theses variable. Neither of the examined genetic polymorphisms associated with a clinical outcome of IgA nephropathy. However, high plasma levels of TNFSF13 increased the risk of ESRD. To explore the causal relationship and underlying mechanism, we treated B cells from patients (n=21) with or without recombinant human TNFSF13 (rhTNFSF13) and measured the expression of IgA and galactose-deficient IgA (GdIgA) using ELISA and flow cytometry. Treatment with rhTNFSF13 significantly increased the total IgA level among B cells, and TNFSF13 receptor blockade abrogated this increase. Furthermore, the absolute levels of GdIgA increased with rhTNFSF13 treatment, but the total IgA-normalized levels did not change. Both RNA sequencing and quantitative PCR results showed that rhTNFSF13 did not alter the expression of glycosyltransferase enzymes. These results suggest that high plasma TNFSF13 levels associate with a worse prognosis of IgA nephropathy through the relative increase in GdIgA levels.

Dysnatremia, its correction, and mortality in patients undergoing continuous renal replacement therapy: a prospective observational study

Background

Although dysnatremia has been reported to be correlated with mortality risk, this issue remains unresolved in patients undergoing continuous renal replacement therapy (CRRT). Furthermore, it has not been determined whether change in or correction of sodium is related to mortality risk in this subset.

Methods

A total of 569 patients were prospectively enrolled at the start of CRRT between May 2010 and September 2013. The patients were divided into 5 groups: normonatremia (135–145 mmol/L), mild hyponatremia (131.1–134.9 mmol/L), moderate to severe hyponatremia (115.4–131.0 mmol/L), mild hypernatremia (145.1–148.4 mmol/L), and moderate to severe hypernatremia (148.5–166.0 mmol/L). The non-linear relationship between sodium and mortality was initially explored. Subsequently, the odds ratios (ORs) for 30-day mortality were calculated after adjustment of multiple covariates.

Results

The relationship between baseline sodium and mortality was U-shaped. The mild hyponatremia, moderate to severe hyponatremia, and moderate to severe hypernatremia groups had greater ORs for mortality (1.65, 1.91, and 2.32, respectively) than the normonatremia group (all P values < 0.05). However, later sodium levels (24 and 72 h after CRRT) did not predict 30-day mortality. Furthermore, the changes in sodium over 24 or 72 h, including the appropriate correction of dysnatremia, did not show any relationships with mortality, irrespective of baseline sodium level.

Conclusions

Sodium level at the start of CRRT was a strong predictor of mortality. However, changes in sodium level and the degree of sodium correction were not associated with the mortality risk in the patients with CRRT.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0215-1) contains supplementary material, which is available to authorized users.

Urinary adiponectin and albuminuria in non-diabetic hypertensive patients: an analysis of the ESPECIAL trial

Background

Although adiponectin levels have been reported to be correlated with albuminuria, this issue remains unresolved in non-diabetic hypertensive subjects, particularly when urinary adiponectin is considered.

Methods

Urinary adiponectin levels were examined using an enzyme-linked immunosorbent assay in 229 participants. who used olmesartan as a hypertensive agent. Their albuminuria levels were measured for 16 weeks after randomization and initiation of conventional or intensive diet education. Linear or logistic regression models were applied, as appropriate, to explore the relationship with albuminuria itself or its response after the intervention.

Results

Urinary adiponectin levels were positively related to baseline albuminuria level (r = 0.529). After adjusting for several covariates, the adiponectin level was associated with the albuminuria level (β = 0.446). Among the 159 subjects with baseline macroalbuminuria, the risk of consistent macroalbuminuria (> 300 mg/day) at 16 weeks was higher in the 3^rd tertile of adiponectin than in the 1^st tertile (odds ratio = 6.9), despite diet education. In contrast, among all subjects, the frequency of the normoalbuminuria achievement (< 30 mg/day) at 16 weeks was higher in the 1^st tertile than in the 3^rd tertile (odds ratio = 13.0).

Conclusions

Urinary adiponectin may be a useful biomarker for albuminuria or its response after treatment in non-diabetic hypertensive patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0124-3) contains supplementary material, which is available to authorized users.

Dialysis Modality and Mortality in the Elderly: A Meta-Analysis

BACKGROUND AND OBJECTIVES

Identifying the appropriate choice between hemodialysis (HD) and peritoneal dialysis (PD) is an unresolved issue in elderly patients with ESRD, who are at high risk for death but have a low chance of receiving kidney transplantation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data on 13,065 incident dialysis Korean patients (age≥65 years) receiving HD (n=10,675) or PD (n=2390) were obtained from the Korean Health Insurance dataset. Multiple statistical approaches, including the multivariate Cox model, were used to compare mortality between Korean patients receiving PD and those receiving HD. Subsequently, meta-analysis of previous comparison studies (published since the year 2000; population-based studies) and the Korean dataset was performed.

RESULTS

During a mean duration of 1.8±1.3 years (maximum of 5 years), the Korean PD group had a higher mortality rate than the Korean HD group (hazard ratio [HR], 1.20 [95% confidence interval (95% CI), 1.13 to 1.28]; P<0.001 by multivariate Cox model). The discrepancy between the two modalities was greater in the presence of certain conditions, such as diabetes mellitus or longer dialysis duration. In the meta-analysis, 15 studies involving >631,421 elderly patients were reviewed. Compared with HD, the pooled HR with PD was 1.10 (95% CI, 1.01 to 1.20). When the meta-analysis was stratified by confounding factors, the survival benefit from HD was particularly strong in subgroups that had diabetes mellitus, had long dialysis duration (>1 year), or contained cohorts starting dialysis in the 1990s.

CONCLUSIONS

A meta-analysis that included results in Korean patients suggests a higher risk for death in elderly patients receiving PD than in those receiving HD.

Effects of acute kidney injury and chronic kidney disease on long-term mortality after coronary artery bypass grafting

BACKGROUND

Both acute kidney injury (AKI) and chronic kidney disease (CKD) are important issues in patients undergoing coronary artery bypass grafting (CABG), particularly with regard to mortality. However, their synergistic or discrete effects on long-term mortality remain unresolved.

METHODS

A total of 1,899 patients undergoing CABG were retrospectively analyzed. The adjusted hazard ratios for all-cause mortality were calculated after stratifying the timeframes. To evaluate the synergistic effects between AKI and CKD, the relative excess risk due to interaction was applied.

RESULTS

The presence of AKI, CKD, or both increased the hazard ratios for mortality, compared with the absence of both: AKI alone, 1.84 (1.464-2.319); CKD alone, 2.46 (1.735-3.478); and AKI and CKD together, 3.21 (2.301-4.488). However, the relationships with mortality were different between AKI and CKD, according to the timeframes: AKI primarily affected early mortality, particularly within 3 years, whereas CKD had a relatively constant effect on both the early and late periods. When the parameters from the relative excess risk due to interaction were obtained, there was a synergistic additive effect on early mortality between AKI and CKD.

CONCLUSIONS

The relationships with mortality after CABG were different between AKI and CKD. However, their effects were not exclusive but synergistic.

Predictive value of echocardiographic parameters for clinical events in patients starting hemodialysis

Echocardiographic parameters can predict cardiovascular events in several clinical settings. However, which echocardiographic parameter is most predictive of each cardiovascular or non-cardiovascular event in patients starting hemodialysis remains unresolved. Echocardiography was used in 189 patients at the time of starting hemodialysis. We established primary outcomes as follows: cardiovascular events (ischemic heart disease, cerebrovascular disease, peripheral artery disease, and acute heart failure), fatal non-cardiovascular events, all-cause mortality, and all combined events. The most predictable echocardiographic parameter was determined in the Cox hazard ratio model with a backward selection after the adjustment of multiple covariates. Among several echocardiographic parameters, the E/e' ratio and the left ventricular end-diastolic volume (LVEDV) were the strongest predictors of cardiovascular and non-cardiovascular events, respectively. After the adjustment of clinical and biochemical covariates, the predictability of E/e' remained consistent, but LVEDV did not. When clinical events were further analyzed, the significant echocardiographic parameters were as follows: s' for ischemic heart disease and peripheral artery disease, LVEDV and E/e' for acute heart failure, and E/e' for all-cause mortality and all combined events. However, no echocardiographic parameter independently predicted cerebrovascular disease or non-cardiovascular events. In conclusion, E/e', s', and LVEDV have independent predictive values for several cardiovascular and mortality events.

U-shape relationship of white blood cells with acute kidney injury and mortality in critically ill patients

Low or high counts of white blood cells (WBCs) and WBC subtypes can be a predictor of morbidity and mortality in several clinical settings. However, the correlations of WBC and its subtypes with acute kidney injury (AKI) and mortality remain unresolved in critically ill patients. The counts of WBC and subtypes, such as neutrophil, lymphocyte, monocyte, and eosinophil, were measured in 2,079 patients admitted to the intensive care unit (ICU) from June 2004 through June 2010. The non-linear relationship between WBC counts and AKI risk was initially explored by a restricted cubic spline analysis. The odds ratios (ORs) for AKI and 1-year mortality were calculated after adjustment for multiple covariates. The relationship between WBC counts and AKI risk was U-shaped. Accordingly, we divided patients into quintiles according to the counts of WBC or subtypes. The 1(st) and 5(th) quintiles of WBC counts had greater ORs for AKI (1.42 and 2.05, respectively) and mortality (1.40 and 1.36, respectively) compared with the 3(rd) quintile. After stratification by WBC subtype, the 5(th) quintile of neutrophil counts and the 1(st) quintiles of lymphocyte and monocyte counts tended to have higher ORs for AKI (1.69, 1.40, and 1.77, respectively). For mortality, the 1(st) quintiles of neutrophil, lymphocyte, and eosinophil counts were associated with higher mortality compared with the 3(rd) quintile (the ORs were 1.48, 1.57, and 1.42, respectively). Both leukopenia and leukocytosis are associated with AKI and mortality risk in critically ill patients. This result may be attributable to the change in the subtype counts.

Pulmonary tuberculosis among patients hospitalised with community-acquired pneumonia in a tuberculosis-prevalent area

SETTING

A suburban teaching hospital in a tuberculosis (TB) prevalent area.

OBJECTIVES

To evaluate the proportion of pulmonary TB among patients hospitalised with suspected community-acquired pneumonia (CAP), and to develop a diagnostic index for identifying TB among these patients.

DESIGN

TB cases confirmed using 1) sputum culture, or 2) both sputum acid-fast bacilli smear and polymerase chain reaction for Mycobacterium tuberculosis, were compared with non-tuberculous CAP by demographic, clinical, laboratory and radiographic information. Using multiple logistic regression analysis, risk factors for TB were identified. A diagnostic index was developed by summing up their simplified regression coefficients. Its performance was checked using c-statistic.

RESULTS

TB was the second leading cause of CAP (37/528, 7.0%). Risk factors were initial symptoms >7 days, serum albumin <3.5 g/dl, cavitary/nodular infiltrates and upper lobe involvement (1 point for each). The c-statistic of the index was 0.856 (95%CI 0.789-0.923), and for bootstrapping samples of 1000 repetitions it was 0.856 (95%CI 0.791-0.921). For scores ≥2, sensitivity and specificity were respectively 81.1% and 75.8%.

CONCLUSION

TB is one of the leading causes of CAP in TB-prevalent areas. Our diagnostic index may help clinicians identify TB immediately from CAP and initiate appropriate isolation and optimal treatment.

Proteinuria and hematuria are associated with acute kidney injury and mortality in critically ill patients: a retrospective observational study

BACKGROUND

Proteinuria and hematuria are both important health issues; however, the nature of the association between these findings and acute kidney injury (AKI) or mortality remains unresolved in critically ill patients.

METHODS

Proteinuria and hematuria were measured by a dipstick test and scored using a scale ranging from a negative result to 3+ in 1883 patients admitted to the intensive care unit. AKI was defined according to the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. The odds ratios (ORs) for AKI and 3-year mortality were calculated after adjustment for multiple covariates according to the degree of proteinuria or hematuria. For evaluating the synergistic effect on mortality among proteinuria, hematuria, and AKI, the relative excess risk due to interaction (RERI) was used.

RESULTS

Proteinuria and hematuria increased the ORs for AKI: the ORs of proteinuria were 1.66 (+/-), 1.86 (1+), 2.18 (2+), and 4.74 (3+) compared with non-proteinuria; the ORs of hematuria were 1.31 (+/-), 1.58 (1+), 2.63 (2+), and 2.52 (3+) compared with non-hematuria. The correlations between the mortality risk and proteinuria or hematuria were all significant and graded (Ptrend<0.001). There was a relative excess risk of mortality when both AKI and proteinuria or hematuria were considered together: the synergy indexes were 1.30 and 1.23 for proteinuria and hematuria, respectively.

CONCLUSIONS

Proteinuria and hematuria are associated with the risks of AKI and mortality in critically ill patients. Additionally, these findings had a synergistic effect with AKI on mortality.