Use of urine biomarker-derived clusters to predict the risk of chronic kidney disease and all-cause mortality in HIV-infected women

Urinary biomarkers in kidney disease

BACKGROUND

Chronic kidney disease (CKD) affects many people worldwide and early diagnosis is essential for successful treatment and improved outcome. Unfortunately, current methods are insufficient especially for early disease detection. However, advances in the analytical methods for urinary biomarkers may provide a unique opportunity for diagnosis and management of CKD. This review explores evolving technology and highlights the importance of early marker detection in these patients.

APPROACH

A search strategy was set up using the terms CKD, biomarkers, and urine. The search included 53 studies comprising 37 biomarkers. The value of these biomarkers for CKD are based on their ability to diagnose CKD, monitor progression, assess mortality and nephrotoxicity.

RESULTS

KIM-1 was the best marker for diagnosis as it increased with the development of incident CKD. DKK3 increased in patients with declining eGFR, whereas UMOD decreased in those with declining kidney function. Unfortunately, none fulfilled all criteria to adequately assess mortality and nephrotoxicity.

CONCLUSION

New developments in the field of urinalysis using smart toilets may open several possibilities for urinary biomarkers. This review explored which biomarkers could be used for CKD disease detection and management.

Ambulatory urine biomarkers associations with acute kidney injury and hospitalization in people with HIV

BACKGROUND

People with HIV (PWH) generally have worse ambulatory levels of kidney injury biomarkers and excess risk of acute kidney injury (AKI) compared to persons without HIV. We evaluated whether ambulatory measures of subclinical kidney injury among PWH are associated with subsequent AKI.

METHODS

In the Predictors of Acute Renal Injury Study (PARIS), which enrolled 468 PWH from April 2016 to August 2019, we measured 10 urine biomarkers of kidney health (albumin, a1m, b2M, NGAL, IL18, KIM-1, EGF, UMOD, MCP-1, YKL40) at baseline and annually during follow-up. Using multivariable Cox regression models, we evaluated baseline and time-updated biomarker associations with the primary outcome of AKI (≥0.3 mg/dl or ≥1.5-times increase in serum creatinine from baseline) and secondary outcome of all-cause hospitalization.

RESULTS

At baseline, the mean age was 53 years old, and 45% self-identified as female. In time-updated models adjusting for sociodemographic factors, comorbidities, albuminuria, estimated glomerular filtration rate, and HIV-associated factors, higher KIM-1 [hazard ratio (HR) = 1.30 per twofold higher; 95% confidence interval (CI) 1.03-1.63] and NGAL concentrations (HR = 1.24, 95% CI 1.06-1.44) were associated with higher risk of hospitalized AKI. Additionally, in multivariable, time-updated models, higher levels of KIM-1 (HR = 1.19, 95% CI 1.00, 1.41), NGAL (HR = 1.13, 95% CI 1.01-1.26), and MCP-1 (HR = 1.20, 95% CI 1.00, 1.45) were associated with higher risk of hospitalization.

CONCLUSIONS

Urine biomarkers of kidney tubular injury, such as KIM-1 and NGAL, are strongly associated with AKI among PWH, and may hold potential for risk stratification of future AKI.

Tubular Secretory Solute Clearance and HIV Infection

BACKGROUND

Tubular secretion is an important kidney function responsible for the clearance of numerous medications, including antibiotics and antivirals. It is unknown whether persons living with HIV have lower secretion compared with HIV-uninfected persons, which might predispose them to the risk of progressive kidney disease or adverse drug events.

SETTING AND METHODS

We evaluated a panel of 6 endogenous secretory solutes in 199 women living with HIV (WLWH) and 100 women without HIV enrolled in the Women's Interagency HIV Study. Secretory clearance was estimated as the urine-to-plasma ratio of each solute, with adjustment for urine tonicity. Using multivariable linear regression analysis, we compared differences in levels of secretory solute clearance between women with and without HIV and evaluated characteristics associated with secretion.

RESULTS

WLWH were older (median 40 vs. 38 years) but had similar estimated glomerular filtration rate (eGFR, 96 vs. 100 mL/minute/1.73 m 2 ) compared with those without HIV. African American and Latino race, diabetes, diastolic blood pressure, smoking, hepatitis C, peak HIV viral load, and current and nadir CD4 count were associated with differences in clearance of at least 1 marker after multivariable adjustment. The secretory clearance of 3 solutes (cinnamoylglycine, kynurenic acid, and pyridoxic acid) were on average 10%-15% lower among WLWH compared with those without HIV independent of eGFR, albuminuria and chronic kidney disease risk factors, including HCV, and injection drug use.

CONCLUSIONS

HIV is associated with reduced secretion among women with preserved eGFR. The implications of these findings for drug dosing and adverse events need to be evaluated.

The use of plasma biomarker-derived clusters for clinicopathologic phenotyping: results from the Boston Kidney Biopsy Cohort

Background

Protein biomarkers may provide insight into kidney disease pathology but their use for the identification of phenotypically distinct kidney diseases has not been evaluated.

Methods

We used unsupervised hierarchical clustering on 225 plasma biomarkers in 541 individuals enrolled into the Boston Kidney Biopsy Cohort, a prospective cohort study of individuals undergoing kidney biopsy with adjudicated histopathology. Using principal component analysis, we studied biomarker levels by cluster and examined differences in clinicopathologic diagnoses and histopathologic lesions across clusters. Cox proportional hazards models tested associations of clusters with kidney failure and death.

Results

We identified three biomarker-derived clusters. The mean estimated glomerular filtration rate was 72.9 ± 28.7, 72.9 ± 33.4 and 39.9 ± 30.4 mL/min/1.73 m2 in Clusters 1, 2 and 3, respectively. The top-contributing biomarker in Cluster 1 was AXIN, a negative regulator of the Wnt signaling pathway. The top-contributing biomarker in Clusters 2 and 3 was Placental Growth Factor, a member of the vascular endothelial growth factor family. Compared with Cluster 1, individuals in Cluster 3 were more likely to have tubulointerstitial disease (P < .001) and diabetic kidney disease (P < .001) and had more severe mesangial expansion [odds ratio (OR) 2.44, 95% confidence interval (CI) 1.29, 4.64] and inflammation in the fibrosed interstitium (OR 2.49 95% CI 1.02, 6.10). After multivariable adjustment, Cluster 3 was associated with higher risks of kidney failure (hazard ratio 3.29, 95% CI 1.37, 7.90) compared with Cluster 1.

Conclusion

Plasma biomarkers may identify clusters of individuals with kidney disease that associate with different clinicopathologic diagnoses, histopathologic lesions and adverse outcomes, and may uncover biomarker candidates and relevant pathways for further study.

Cystatin C and Urine Albumin to Creatinine Ratio Predict 5-Year Mortality and Cardiovascular Events in People Living With HIV

BACKGROUND

Identifying people with HIV (PWH) at risk for chronic kidney disease, cardiovascular events, and death is crucial. We evaluated biomarkers to predict all-cause mortality and cardiovascular events, and measured glomerular filtration rate (mGFR) slope.

METHODS

Biomarkers were measured at enrollment. Baseline and 5-year mGFR were measured by plasma iohexol clearance. Outcomes were a composite criterion of all-cause mortality and/or cardiovascular events, and mGFR slope.

RESULTS

Of 168 subjects, 146 (87.4%) had undetectable HIV load. Median follow-up was 59.1 months (interquartile range, 56.2-62.1). At baseline, mean age was 49.5 years (± 9.8) and mean mGFR 98.9 mL/min/1.73m2 (± 20.6). Seventeen deaths and 10 cardiovascular events occurred during 5-year follow-up. Baseline mGFR was not associated with mortality/cardiovascular events. In multivariable analysis, cystatin C (hazard ratio [HR], 5.978; 95% confidence interval [CI], 2.774-12.88; P < .0001) and urine albumin to creatinine ratio (uACR) at inclusion (HR, 1.002; 95% CI, 1.001-1.004; P < .001) were associated with mortality/cardiovascular events. Area under receiver operating curve of cystatin C was 0.67 (95% CI, .55-.79) for mortality/cardiovascular event prediction. Biomarkers were not associated with GFR slope.

CONCLUSIONS

uACR and cystatin C predict all-cause mortality and/or cardiovascular events in PWH independently of mGFR.

Urine Markers of Kidney Tubule Cell Injury and Kidney Function Decline in SPRINT Trial Participants with CKD

BACKGROUND AND OBJECTIVES

eGFR and albuminuria primarily reflect glomerular function and injury, whereas tubule cell atrophy and interstitial fibrosis on kidney biopsy are important risk markers for CKD progression. Kidney tubule injury markers have primarily been studied in hospitalized AKI. Here, we examined the association between urinary kidney tubule injury markers at baseline with subsequent loss of kidney function in persons with nondiabetic CKD who participated in the Systolic Blood Pressure Intervention Trial (SPRINT).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Among 2428 SPRINT participants with CKD (eGFR<60 ml/min per 1.73 m²) at baseline, we measured urine markers of tubule injury (IL-18, kidney injury molecule-1 [KIM-1], neutrophil gelatinase-associated lipocalin [NGAL]), inflammation (monocyte chemoattractant protein-1 [MCP-1]), and repair (human cartilage glycoprotein-40 [YKL-40]). Cox proportional hazards models evaluated associations of these markers with the kidney composite outcome of 50% eGFR decline or ESKD requiring dialysis or kidney transplantation, and linear mixed models evaluated annualized change in eGFR.

RESULTS

Mean participant age was 73±9 (SD) years, 60% were men, 66% were white, and mean baseline eGFR was 46±11 ml/min per 1.73 m². There were 87 kidney composite outcome events during a median follow-up of 3.8 years. Relative to the respective lowest quartiles, the highest quartiles of urinary KIM-1 (hazard ratio, 2.84; 95% confidence interval [95% CI], 1.31 to 6.17), MCP-1 (hazard ratio, 2.43; 95% CI, 1.13 to 5.23), and YKL-40 (hazard ratio, 1.95; 95% CI, 1.08 to 3.51) were associated with higher risk of the kidney composite outcome in fully adjusted models including baseline eGFR and urine albumin. In linear analysis, urinary IL-18 was the only marker associated with eGFR decline (-0.91 ml/min per 1.73 m² per year for highest versus lowest quartile; 95% CI, -1.44 to -0.38), a finding that was stronger in the standard arm of SPRINT.

CONCLUSIONS

Urine markers of tubule cell injury provide information about risk of subsequent loss of kidney function, beyond the eGFR and urine albumin.

Management of Presumed Acute Kidney Injury during Hypertensive Therapy: Stay Calm and Carry on?

BACKGROUND

Recent studies have demonstrated that intensive blood pressure control is associated with improved cardiovascular outcomes. Acute kidney injury (AKI), however, was more common in the intensive treatment group prompting concern in the nephrology community.

SUMMARY

Clinical trials on hypertension control have traditionally defined AKI by changes in serum creatinine. However, serum creatinine has several inherent limitations as a marker of kidney injury, with various factors influencing its production, secretion, and elimination. Urinary biomarkers of kidney injury and repair have the potential to provide insight on the presence and phenotype of kidney injury. In both the Systolic Blood Pressure Intervention Trial and the Action to Control Cardiovascular Risk in Diabetes study, urinary biomarkers have suggested that the increased risk of AKI associated with intensive treatment was due to hemodynamic changes rather than structural kidney injury. As such, clinicians who encounter rises in serum creatinine during intensification of hypertension therapy should "stay calm and carry on." Alternative explanations for serum creatinine elevation should be considered and addressed if appropriate. When the rise in serum creatinine is limited, particularly if albuminuria is stable or improving, intensive blood pressure control should be continued for its potential long-term benefits. Key Messages: Increases in serum creatinine during intensification of blood pressure control may not necessarily reflect kidney injury. Clinicians should evaluate for other contributing factors before stopping therapy. Urinary biomarkers may address limitations of serum creatinine as a marker of kidney injury.

Development and validation of a prognostic nomogram for HIV/AIDS patients who underwent antiretroviral therapy: Data from a China population-based cohort

BACKGROUND

Accurate forecast of the death risk is crucial to the administration of people living with HIV/AIDS (PLHIV). We aimed to establish and validate an effective prognosis nomogram in PLHIV receiving antiretroviral therapy (ART).

METHODS

All the data were obtained from 2006 to 2018 in the Wenzhou area from China AIDS prevention and control information system. Factors included in the nomogram were determined by univariate and multiple Cox proportional hazard analysis based on the training set. The receiver operating characteristic (ROC) and calibration curves were used to assess its predictive accuracy and discriminative ability. Its clinical utility was also evaluated using decision curve analysis (DCA), X-tile analysis and Kaplan-Meier curve, respectively in an independent validation set.

FINDINGS

Independent prognostic factors including haemoglobin, viral load and CD4+ T-cell count were determined and contained in the nomogram. Good agreement between the prediction by nomogram and actual observation could be detected in the calibration curve for mortality, especially in the first year. In the training cohort, AUC (95% CI) and C-index (95% CI) were 0.93 (0.90, 0.96) and 0.90 (0.85, 0.96), respectively. In the validation set, the nomogram still revealed excellent discriminations [AUC (95% CI): 0.95 (0.91, 1.00)] and good calibration [C-index (95% CI): 0.92 (0.82-1.00)]. Moreover, DCA also demonstrated that the nomogram was clinical beneficial. Additionally, participants could be classified into three distinct (low, middle and high) risk groups by the nomogram.

INTERPRETATION

The nomogram presents accurate and favourable prognostic prediction for PLHIV who underwent ART.

FUNDING

This work was supported by Zhejiang Basic Public Welfare Research Project (LGF19H260011), Wenzhou Basic Public Welfare Research Project (Y20180201), the Initial Scientific Research Fund (KYQD170301), the Major Project of the Eye Hospital Wenzhou the Major Project of the Eye Hospital Wenzhou Medical University (YNZD201602). Part of this work was also funded by National Natural Science Foundation of China (81670777) and Science and Technology Innovation Activity Plan and New Talents Plan for College Students in Zhejiang Province (2019R413073). The funders had no roles in study design, data collection, data analysis, interpretation and writing of the report.

Kidney disease risk factors associate with urine biomarkers concentrations in HIV-positive persons; a cross-sectional study

Background

HIV-positive persons bear an excess burden of chronic kidney disease (CKD); however, conventional methods to assess kidney health are insensitive and non-specific for detecting early kidney injury. Urinary biomarkers can detect early kidney injury, and may help mitigate the risk of overt CKD.

Methods

Cross-sectional study of HIV-positive persons in the Multicenter AIDS Cohort Study and the Women’s Interagency HIV Study. We measured levels of 14 biomarkers, capturing multiple dimensions of kidney injury. We then evaluated associations of known CKD risk factors with urine biomarkers using separate multivariable adjusted models for each biomarker.

Results

Of the 198 participants, one third were on HAART and virally suppressed. The vast majority (95%) had preserved kidney function as assessed by serum creatinine, with a median eGFR of 103 ml/min/1.73 m² (interquartile range (IQR): 88, 116). In our multivariable analyses, the associations of each CKD risk factor with urinary biomarker levels varied in magnitude. For example, HIV viral load was predominantly associated with elevations in interleukin(IL)-18, and albuminuria, while higher CD4 levels were associated with lower monocyte chemoattractant protein-1 (MCP-1) and β2-microglobulin. In contrast, older age was significantly associated with elevations in α1-microglobulin, kidney injury marker-1, clusterin, MCP-1, and chitinase-3-like protein-1 levels, as well as lower epidermal growth factor, and uromodulin levels.

Conclusions

Among HIV-positive persons, CKD risk factors are associated with unique and heterogeneous patterns of changes in urine biomarkers levels. Additional work is needed to develop parsimonious algorithms that integrate multiple biomarkers and clinical data to discern the risk of overt CKD and its progression.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1192-y) contains supplementary material, which is available to authorized users.

Effects of Intensive Blood Pressure Lowering on Kidney Tubule Injury in CKD: A Longitudinal Subgroup Analysis in SPRINT

BACKGROUND

Random assignment to the intensive systolic blood pressure (SBP) arm (<120mmHg) in the Systolic Blood Pressure Intervention Trial (SPRINT) resulted in more rapid declines in estimated glomerular filtration rates (eGFRs) than in the standard arm (SBP<140mmHg). Whether this change reflects hemodynamic effects or accelerated intrinsic kidney damage is unknown.

STUDY DESIGN

Longitudinal subgroup analysis of clinical trial participants.

SETTINGS & PARTICIPANTS

Random sample of SPRINT participants with prevalent chronic kidney disease (CKD) defined as eGFR<60mL/min/1.73m² by the CKD-EPI (CKD Epidemiology Collaboration) creatinine-cystatin C equation at baseline.

OUTCOMES & MEASUREMENTS

Urine biomarkers of tubule function (β₂-microglobulin [B2M], α₁-microglobulin [A1M]), and uromodulin), injury (interleukin 18, kidney injury molecule 1, and neutrophil gelatinase-associated lipocalin), inflammation (monocyte chemoattractant protein 1), and repair (human cartilage glycoprotein 40) at baseline, year 1, and year 4. Biomarkers were indexed to urine creatinine concentration and changes between arms were evaluated using mixed-effects linear models and an intention-to-treat approach.

RESULTS

978 SPRINT participants (519 in the intensive and 459 in the standard arm) with prevalent CKD were included. Mean age was 72±9 years and eGFR was 46.1±9.4mL/min/1.73m² at baseline. Clinical characteristics, eGFR, urinary albumin-creatinine ratio, and all 8 biomarker values were similar across arms at baseline. Compared to the standard arm, eGFR was lower by 2.9 and 3.3mL/min/1.73m² in the intensive arm at year 1 and year 4. None of the 8 tubule marker levels was higher in the intensive arm compared to the standard arm at year 1 or year 4. Two tubule function markers (B2M and A1M) were 29% (95% CI, 10%-43%) and 24% (95% CI, 10%-36%) lower at year 1 in the intensive versus standard arm, respectively.

LIMITATIONS

Exclusion of persons with diabetes, and few participants had advanced CKD.

CONCLUSIONS

Among participants with CKD in SPRINT, random assignment to the intensive SBP arm did not increase any levels of 8 urine biomarkers of tubule cell damage despite loss of eGFR. These findings support the hypothesis that eGFR declines in the intensive arm of SPRINT predominantly reflect hemodynamic changes rather than intrinsic damage to kidney tubule cells.

Chronic Kidney Disease and Antiretroviral Therapy in HIV-Positive Individuals: Recent Developments

Chronic kidney disease (CKD) has emerged as an important health concern in HIV-positive individuals. Preventing long-term kidney toxicity from an antiretroviral therapy is therefore critical. Selected antiretroviral agents, especially tenofovir disoproxil fumarate (TDF) and some ritonavir-boosted protease inhibitors (PI/rs), have been associated with increased risk of CKD. However, the CKD risk attributable to these agents is overall small, especially in those with low baseline risk of CKD and normal renal function. CKD risk in HIV-positive individuals can be further minimized by timely identification of those with worsening renal function and discontinuation of potentially nephrotoxic agents. Clinicians can use several monitoring tools, including the D:A:D risk score and routine measurements of estimated glomerular filtration (eGFR) and proteinuria, to identify high-risk individuals who may require an intervention. Tenofovir alafenamide (TAF), a TDF alternative, promises to be safer in terms of TDF-associated kidney and bone toxicity. While the short-term data on TAF does indicate lower eGFR decline and lower risk of proteinuria (vs. TDF), long-term data on renal safety of TAF are still awaited. Promising results have also emerged from recent trials on alternative dual-therapy antiretroviral regimens which exclude the nucleoside(tide) reverse transcriptase class as well as possibly the PI/rs, thereby reducing the drug burden, and possibly the toxicity. However, long-term safety or benefits of these dual-therapy regimens are still unclear and will need to be studied in future prospective studies. Finally, addressing risk factors such as hypertension and diabetes will continue to be important in this population.

Group analysis identifies differentially elevated biomarkers with distinct outcomes for advanced acute kidney injury in cardiac surgery

AIM

To investigate early postoperative biomarkers for risk discrimination of advanced acute kidney injury (AKI).

MATERIALS & METHODS

Postoperative plasma biomarkers including NGAL, h-FABP, CK-MB, hsTNT, NT-proBNP, IL-6, IL-10 and VEGF were analyzed using group-based method among 426 patients with AKI after cardiac surgery.

RESULTS

Six patient groups with distinct biomarker patterns were identified. Individual biomarker displayed significant difference across the groups. The groups showed better discrimination for advanced AKI than any single biomarker either with or without adjusting for clinical variables. Average concentration of a single biomarker within each group, mortality and risk of a secondary outcome all demonstrated an approximately U-shaped relationship with proportion of advanced AKI within each group.

CONCLUSION

The group-based analysis revealed that the order of the patient groups with an increasing likelihood of advanced AKI had a nonlinear relationship with average concentration of an individual biomarker, mortality and risk of other outcomes.

Diagnostic challenges of kidney diseases in HIV-infected patients

INTRODUCTION

Chronic kidney disease (CKD) is a prevalent comorbidity in persons living with HIV infection (PLWH) associated with an increase in cardiovascular morbidity and all-cause mortality. Furthermore, early diagnosis of CKD is difficult in PLWH. Areas covered: We reviewed the main diagnostic tools for CKD in PLWH, and discussed their strengths and limits. We performed a literature search on PubMed to identify reviews and clinical trials dealing with attractive kidney biomarkers of CKD in PLWH, with the following key words: 'HIV AND kidney', 'HIV AND Kidney biomarkers', 'CKD AND Kidney biomarkers'. Expert commentary: Currently, CKD diagnosis is based on the estimation of Glomerular Filtration Rate (GFR), and measurement of proteinuria by urine protein/creatinine ratio (uPCR). These parameters are independent and complementary predictors of outcomes. GFR estimates are lacking in accuracy in PLWH. The best GFR estimate is CKD-EPI study equation. Moreover, low-grade proteinuria is associated with an increased risk of kidney disease progression in PLWH, and guidelines derived from the general population may lack sensitivity. Different biomarkers of kidney diseases like N-acetyl beta glucosaminidase (NAG), Kidney Injury Molecule-1 (KIM-1), and Alpha-1-microglobulin may predict kidney disease progression and mortality in PLWH. Others may help clinicians detect antiretroviral-induced tubulopathy, or predict cardiovascular events. More studies are needed to validate the routine use of these types of biomarkers.

Changes in Urinary Biomarkers Over 10 Years Is Associated With Viral Suppression in a Prospective Cohort of Women Living With HIV

BACKGROUND

Urine biomarkers have helped identify persons at risk for progressing to kidney disease in the setting of HIV infection. We explored factors associated with changes in 3 urine biomarkers over 10 years among women living with HIV.

METHODS

Prospective cohort of 294 HIV-infected women from the multicenter Women's Interagency HIV Study. Predictors included HIV viral and immunological parameters, comorbid conditions, and health-related behaviors. Outcomes were patterns of changes of urine interleukin-18 (IL-18), albumin-to-creatinine ratio (ACR), and alpha-1-microglobulin (α1m) over 10 years. We used quantile regression to examine patterns of change in each urine biomarker during follow-up and multivariable analysis of variance regression to identify predictors of biomarker changes.

RESULTS

Over 10 years, the median concentrations of IL-18 declined from 120 to 64 pg/mL, α1m rose from 0.7 to 1.5 ng/mL, and ACR remained stable (9-8 mg/g). In multivariate analyses, the strongest predictors of increases in IL-18 were higher baseline body mass index, increase in waist circumference, higher follow-up HIV viral load, lower follow-up CD4 cell count, hepatitis C virus (HCV) coinfection, and higher follow-up high density lipoprotein cholesterol. Predictors of increasing concentration of α1m were lower CD4 cell counts, higher diastolic blood pressure, HCV coinfection, and smoking. Finally, determinants of ACR increases during follow-up were higher follow-up diastolic blood pressure, HCV coinfection, higher follow-up HIV viral load, and triglyceride concentration.

CONCLUSIONS

Over 10 years, HIV disease status had different associations with each urine biomarker under study. Overall, the associations with changes in each biomarker support research into their use for longitudinal monitoring of kidney health.