Tenofovir use and urinary biomarkers among HIV-infected women in the Women's Interagency HIV Study (WIHS)

Is urinary β2-microglobulin a reliable marker for assessment of renal tubular dysfunction in chronic hepatitis B patients receiving tenofovir therapy?

BACKGROUND AND AIM

Urinary β2-microglobulin (β2-M) is a marker for renal tubular dysfunction. The current study aimed to assess urinary β2-M as a reliable marker for early prediction of tenofovir disoproxil fumarate (TDF)-related nephrotoxicity among hepatitis B virus (HBV) patients.

METHODS

Forty-two HBV patients who were a candidate for TDF therapy or have recently started it (for less than 6 months) were enrolled and subjected to demographic, clinical, laboratory assessment, abdominal ultrasound and transient elastography. The glomerular filtration rate (GFR) was estimated using the Cockcroft-Gault equation. Also, urinary β2-M was measured by the ELISA method within 6 months after the introduction of TDF treatment and 6 months later.

RESULTS

Mean age was 41.8 (9.55) years, 27 were males and 59.5% of patients have elevated urinary β2-M after 6 months follow-up of TDF therapy. Urinary β2-M was 0.07 ± 0.07 μg/ml at baseline and insignificantly increased up to 0.09 ± 0.08 μg/ml after 6 months follow-up. Despite the insignificant increase in serum creatinine from 0.85 ± 0.23 mg/dl at baseline to 0.9 ± 0.21 mg/dl after 6 months and the insignificant decrease in eGFR from 126.2 ± 39.72 ml/min at baseline and 117.64 ± 42.23 ml/min at 6 months follow-up. No correlation was found between the changes in urinary β2-M and the changes in other renal function indices at baseline and 6 months follow-up.

CONCLUSIONS

Short-term TDF therapy is associated with nonsignificant changes either in eGFR or urinary β2-M; these changes are not clinically relevant that indicates disease progression. Therefore, the suitability of urinary β2-M as a screening tool for tenofovir induced tubular dysfunction should be further.

Biomarker-guided management of acute kidney injury

PURPOSE OF REVIEW

The current narrative review discusses practical applications of stress and damage biomarkers for the management of acute kidney injury (AKI) based on clinical trials and real-world evaluations.

RECENT FINDINGS

In 2013 with the discovery and validation study of biomarkers for AKI (Sapphire) advancement in care was provided allowing for the early identification of patients at high risk for developing AKI. It was the combination of new biomarkers and the Kidney Disease Improving Global Outcomes (KDIGO) guidelines for managing patients with AKI that provided an opportunity to improve patient care. In 2017, the PrevAKI study implemented KDIGO guideline management in high-risk patients identified by biomarkers followed in 2018 with the BigPAK study that used a similar approach, both of which demonstrated positive outcomes in patient care. Next, real-world evaluations followed supporting biomarker guided management of AKI in clinical practice. Also, proposals for better nephrotoxin management, a major modifiable exposure to prevent AKI, were provided with the foresight in identifying high-risk patients.

SUMMARY

Stress and damage biomarker-based approaches to patient care seem to be promising for identifying patients at high risk for developing AKI and thus offers an opportunity for early management to prevent and ameliorate AKI and drug-associated AKI.

Antiretroviral Concentration in Hair as a Measure for Antiretroviral Medication Adherence: A Systematic Review of Global Literature

This review aims to validate hair antiretroviral concentration (HAC) as a measure for antiretroviral medication adherence. This review included 31 studies that analyzed a total of 11 ARV drugs in four different drug classes. The associations between HAC and non-pharmacokinetic measures were generally lower than the association between HAC and other pharmacokinetic measures: the correlation coefficients (r) ranged from - 0.20 to 0.38 for self-report or pill counts and 0.20 to 0.85 for electronic drug monitoring; HAC and other pharmacokinetic measures were positively correlated with the correlation coefficients (r) ranging from 0.20 to 0.72, 0.34 to 0.86, 0.50 to 0.85 for antiretroviral concentration in plasma, peripheral blood mononuclear cells, and dried blood spots, respectively. HAC was one of the strongest independent predictors of virologic responses. HAC of tenofovir was significantly associated with renal toxicity in large sample studies. This review suggests that HAC is a valid biomarker of antiretroviral medication adherence.

Utility of urinary liver-type fatty acid-binding protein as a predictor of renal dysfunction in Japanese patients with HIV receiving tenofovir disoproxil fumarate with low urinary β2 microglobulin levels: a retrospective observational study

Background

Tenofovir disoproxil fumarate (TDF) is known to reduce estimated glomerular filtration rate (eGFR). It is clinically important to identify patients at high risk for renal dysfunction as early as possible. Among the tubular markers, urinary β2 microglobulin (Uβ2MG) is a well-known biomarker of TDF-related tubulopathy. However, renal dysfunction has often been occurred in patients receiving TDF with low Uβ2MG levels. Recently, urinary liver-type fatty acid–binding protein (UL-FABP) was suggested to be predictor of the progression of renal dysfunction. Thus, we focused on UL-FABP in patients receiving TDF with low Uβ2MG levels.

Methods

A retrospective, observational, single-center study, between January 2013 and December 2016, was conducted. Two renal end points (> 25% decrement in eGFR and > 20 mL/min/1.73 m² decrement relative to the baseline) were assessed. To estimate the effect of UL-FABP on time to the first event, log-rank test was performed.

Results

A total of 24 Japanese outpatients with human immunodeficiency virus receiving TDF were enrolled. The outcome each occurred in two patients during the follow-up period. UL-FABP levels ≥4.0 μg/g creatinine was significantly associated with > 25% decrement and > 20 mL/min/1.73 m² decrement (p = 0.006 and 0.001, respectively).

Conclusion

Based on our preliminary analysis, UL-FABP levels ≥4.0 μg/g creatinine predict renal dysfunction in patients receiving TDF with low Uβ2MG levels.

Tenofovir disoproxil fumarate initiation and changes in urinary biomarker concentrations among HIV-infected men and women

OBJECTIVES

Urinary biomarkers of kidney injury may have potential to identify subclinical injury attributable to tenofovir disoproxil fumarate (TDF) toxicity.

DESIGN

This observational study included 198 HIV-infected participants from the Multicenter AIDS Cohort Study and the Women's Interagency HIV Study, who initiated TDF between 2009 and 2015 and had urine samples collected at baseline before and after TDF initiation.

METHODS

We used linear mixed-effects models controlling for urine creatinine and time on TDF to evaluate the effects of TDF initiation on changes in 14 urinary biomarkers.

RESULTS

Within 1 year after TDF initiation, concentrations of trefoil factor 3 [+78%; 95% confidence interval (CI) +38%, +129%), alpha-1 microglobulin (α1m) (+32%; 95% CI +13%, +55%), clusterin (+21%; 95% CI +6%, +38%), uromodulin (+19%; 95% CI +4%, +36%), and kidney injury molecule-1 (KIM-1) (+13%; 95% CI +1%, +26%) significantly increased, whereas interleukin-18 (IL-18) significantly decreased (-13%, 95% CI -7%, -25%). Subsequent to the first year of TDF use, biomarker concentrations stabilized, and these changes were not statistically significant. When stratifying by baseline viremia (HIV-1 RNA < vs. ≥80 copies/ml), concentration changes for most biomarkers during the first year of TDF use were greater among aviremic vs. viremic participants, with significant differences in α1m (+80 vs. +22%), KIM-1 (+43 vs. +10%), beta-2 microglobulin (+83 vs. -10%), YKL-40 (+33 vs. -5%), and IL-18 (+20 vs. -27%).

CONCLUSIONS

TDF initiation was associated with substantial changes in urinary biomarkers of kidney injury within the first year of use, particularly among aviremic participants. A urinary biomarker panel may be a clinically useful tool to detect and monitor the heterogeneous effects of TDF on the kidney.

Correlation Between Tenofovir Drug Levels and the Renal Biomarkers RBP-4 and ß2M in the ION-4 Study Cohort

Background

Concomitant dosing of ledipasvir (LDV) and tenofovir disoproxil fumarate (TDF) results in an increased tenofovir (TFV) area under the curve (AUC). The aim of this study was to examine whether there was a correlation between the renal biomarkers retinol binding protein–4 (RBP-4) and β2 microglobulin (β2M) and tenofovir AUC.

Methods

The ION-4 trial enrolled HIV/hepatitis C virus–coinfected patients on nonpharmacologically boosted antiretroviral regimens with TDF-containing backbones. We assessed for a correlation between tenofovir AUC and urinary biomarkers and also for changes in serologic biomarkers with respect to clinically relevant changes in renal function (creatinine clearance decrease >25%, change in creatinine >0.2 mg/dL, change in proteinuria from negative/trace to ≥1+).

Results

Three hundred thirty-five patients were enrolled in the ION-4 study; their demographic characteristics have been previously described. Both RBP-4 and β2M exhibited positive correlations with tenofovir AUC. Baseline and study levels of RBP-4 and β2M were higher for patients with increases in urine proteinuria and an absolute creatinine increase.

Conclusions

TFV exposure is associated with increased proximal tubule urine biomarkers in participants on ledipasvir/sofosbuvir and nonpharmacologically boosted TDF-based antiretroviral regimens. Baseline proximal tubule biomarkers may predict nephrotoxicity risk if events are prevalent. Further studies assessing the predictive role of these urine biomarkers may help guide medical decision-making and risk/benefit assessments in patients with risk factors for renal dysfunction.

Clinical Relevance and Predictive Value of Damage Biomarkers of Drug-Induced Kidney Injury

Nephrotoxin exposure accounts for up to one-fourth of acute kidney injury episodes in hospitalized patients, and the associated consequences are as severe as acute kidney injury due to other etiologies. As the use of nephrotoxic agents represents one of the few modifiable risk factors for acute kidney injury, clinicians must be able to identify patients at high risk for drug-induced kidney injury rapidly. Recently, significant advancements have been made in the field of biomarker utilization for the prediction and detection of acute kidney injury. Such biomarkers may have a role both for detection of drug-induced kidney disease and implementation of preventative and therapeutic strategies designed to mitigate injury. In this article, basic principles of renal biomarker use in practice are summarized, and the existing evidence for six markers specifically used to detect drug-induced kidney injury are outlined, including liver-type fatty acid binding protein, neutrophil gelatinase-associated lipocalin, tissue inhibitor of metalloproteinase-2 times insulin-like growth factor-binding protein 7 ([TIMP-2]·[IGFBP7]), kidney injury molecule-1 and N-acetyl-β-D-glucosaminidase. The results of the literature search for these six kidney damage biomarkers identified 29 unique articles with none detected for liver-type fatty acid binding protein and [TIMP-2]·[IGFBP7]. For three biomarkers, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin and N-acetyl-β-D-glucosaminidase, the majority of the studies suggest utility in clinical practice. While many questions need to be answered to clearly articulate the use of biomarkers to predict drug-induced kidney disease, current data are promising.

Differences in acute kidney injury ascertainment for clinical and preclinical studies

Background

Acute kidney injury (AKI) is a common clinical condition directly associated with adverse outcomes. Several AKI biomarkers have been discovered, but their use in clinical and preclinical studies has not been well examined. This study aims to investigate the differences between clinical and preclinical studies on AKI biomarkers.

Methods

We performed a systematic review of clinical and preclinical interventional studies that considered AKI biomarkers in enrollment criteria and/or outcome assessment and described the main differences according to their setting, the inclusion of biomarkers in the definition of AKI and the use of biomarkers as primary or secondary end points.

Results

In the 151 included studies (76 clinical, 75 preclinical), clinical studies have prevalently focused on cardiac surgery (38.1%) and contrast-associated AKI (17.1%), while the majority of preclinical studies have focused on ether ischemia-reperfusion injury or drug-induced AKI (42.6% each). A total of 57.8% of clinical studies defined AKI using the standard criteria and only 19.7% of these studies used AKI biomarkers in the definition of renal injury. Conversely, the majority of preclinical studies defined AKI according to the increase in serum creatinine and blood urea nitrogen, and 32% included biomarkers in that definition. The percentage of both clinical and preclinical studies with biomarkers as a primary end point has not significantly increased in the last 10 years; however, preclinical studies are more likely to use AKI biomarkers as a primary end point compared with clinical studies [odds ratio 2.31 (95% confidence interval 1.17-4.59); P  =  0.016].

Conclusion

Differences between clinical and preclinical studies are evident and may affect the translation of preclinical findings in the clinical setting.

Tenofovir disoproxil fumarate co-administered with lopinavir/ritonavir is strongly associated with tubular damage and chronic kidney disease

BACKGROUD

With expanding antiretroviral therapy (ART) in a resource-limited setting, the use of second line ART with ritonavir boosted lopinavir (LPV/r) is increasing. However, little is known regarding the renal safety of tenofovir (TDF) co-administered with LPV/r.

METHODS

In total 1382 HIV-infected patients were enrolled and data were recorded twice (October 2014 and 2015) in Vietnam. Tubular dysfunction (TD) was defined as urinary beta 2 microglobulin (β2MG) > 1000 μg/L at both timepoints or increase in β2MG by > 2000 μg/L. Chronic kidney disease (CKD) was defined as creatinine clearance ≤60 ml/min or urinary protein/creatinine ratio ≥ 0.15 g/gCre at both timepoints.

RESULTS

The patients'mean weight and age were 55.9 kg and 38.4 years, respectively, and 41.5% were female. Additionally, 98.2% were on ART, 76.3% were on TDF (mean exposure duration was 35.4 months), and 22.4% had never TDF exposure. TD and CKD were diagnosed in 13% and 8.3% of all patients, respectively. In multivariate analyses, age (OR = 1.057; 95%CI, 1.034-1.081), being female (OR = 0.377; 95%CI, 0.221-0.645), HBsAg positive (OR = 1.812; 95%CI, 1.134-2.894), HCVAb positive (OR = 1.703; 95%CI, 1.100-2.635), TDF exposure (OR = 9.226; 95%CI, 2.847-29.901) and LPV/r exposure (OR = 5.548; 95%CI, 3.313-9.293) were significantly associated with TD. Moreover, age (OR = 1.093; 95%CI, 1.068-1.119), being female (OR = 0.510; 95%CI, 0.295-0.880), weight (OR = 0.909; 95%CI, 0.879-0.939), hypertension (OR = 3.027; 95%CI, 1.714-5.347), TDF exposure (OR = 1.963; 95%CI, 1.027-3.7 53) and LPV/r exposure (OR = 3.122; 95%CI, 1.710-5.699) were significantly associated with CKD.

CONCLUSIONS

TDF and LPV/r exposure were strongly associated with TD and CKD, in addition to their known risks. Therefore, attention to renal safety for patients on second line ART is necessary.

Reversal of Proximal Renal Tubular Dysfunction after Nucleotide Analogue Withdrawal in Chronic Hepatitis B

Aims

Proximal renal tubular dysfunction (PRTD) is an infrequent complication after nucleotide analogue therapy. We evaluated the outcomes of PRTD and nephrotoxicity after nucleotide analogue withdrawal in chronic hepatitis B (CHB).

Methods

A longitudinal follow-up study was performed in patients with PRTD after nucleotide analogue discontinuation. Serum and urine were collected at baseline and every 3 months for one year. The fractional excretion of phosphate (PO₄), uric acid (UA), and potassium and tubular maximal reabsorption rate of PO₄ to glomerular filtration rate (TmPO₄/GFR) were calculated. Renal losses were defined based on the criteria of substance losses. Subclinical PRTD and overt PRTD were diagnosed when 2 and ≥3 criteria were identified.

Results

Eight subclinical and eight overt PRTD patients were enrolled. After nucleotide analogue withdrawal, there were overall improvements in GFR, serum PO₄, and UA. Renal loss of PO₄, UA, protein, and β2-microglobulin reduced over time. At one year, complete reversal of PRTD was seen in 13 patients (81.2%). Improvements in PRTD were seen in all but one patient.

Conclusion

One year after nucleotide analogue withdrawal, PRTD was resolved in most patients. Changes in TmPO₄/GFR, urinary protein, and β2-microglobulin indicate that urinary biomarkers may represent an early sign of PRTD recovery.

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.

Rediscovering Beta-2 Microglobulin As a Biomarker across the Spectrum of Kidney Diseases

There is currently an unmet need for better biomarkers across the spectrum of renal diseases. In this paper, we revisit the role of beta-2 microglobulin (β₂M) as a biomarker in patients with chronic kidney disease and end-stage renal disease. Prior to reviewing the numerous clinical studies in the area, we describe the basic biology of β₂M, focusing in particular on its role in maintaining the serum albumin levels and reclaiming the albumin in tubular fluid through the actions of the neonatal Fc receptor. Disorders of abnormal β₂M function arise as a result of altered binding of β₂M to its protein cofactors and the clinical manifestations are exemplified by rare human genetic conditions and mice knockouts. We highlight the utility of β₂M as a predictor of renal function and clinical outcomes in recent large database studies against predictions made by recently developed whole body population kinetic models. Furthermore, we discuss recent animal data suggesting that contrary to textbook dogma urinary β₂M may be a marker for glomerular rather than tubular pathology. We review the existing literature about β₂M as a biomarker in patients receiving renal replacement therapy, with particular emphasis on large outcome trials. We note emerging proteomic data suggesting that β₂M is a promising marker of chronic allograft nephropathy. Finally, we present data about the role of β₂M as a biomarker in a number of non-renal diseases. The goal of this comprehensive review is to direct attention to the multifaceted role of β₂M as a biomarker, and its exciting biology in order to propose the next steps required to bring this recently rediscovered biomarker into the twenty-first century.

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.

COHORT PROFILE: The Complications of Long-Term Antiretroviral Therapy study in Uganda (CoLTART), a prospective clinical cohort

BACKGROUND

Antiretroviral therapy (ART) improves the survival and quality of life of HIV-positive individuals, but the effects of long-term ART use do eventually manifest. The Complications of Long-Term Antiretroviral Therapy cohort study in Uganda (CoLTART) was established to investigate the metabolic and renal complications of long-term ART use among Ugandan adults. We describe the CoLTART study set-up, aims, objectives, study methods, and also report some preliminary cross-sectional study enrolment metabolic and renal complications data analysis results.

METHODS

HIV-positive ART naïve and experienced adults (18 years and above) in Uganda were enrolled. Data on demographic, dietary, medical, social economic and behaviour was obtained; and biophysical measurements and a clinical examination were undertaken. We measured: fasting glucose and lipid profiles, renal and liver function tests, full blood counts, immunology, virology and HIV drug resistance testing. Plasma samples were stored for future studies.

RESULTS

Between July 2013 and October 2014, we enrolled 1095 individuals, of whom 964 (88.0%) were ART experienced (6 months or more), with a median of 9.4 years (IQR 7.0-9.9) on ART. Overall, 968 (88.4%) were aged 35 years and above, 711 (64.9%) were females, 608 (59.6%) were or had ever been on a Tenofovir ART regimen and 236 (23.1%) on a Protease Inhibitor (PI) regimen. There were no differences in renal dysfunction between patients on Tenofovir and Non-Tenofovir containing ART regimens. Patients on PI regimens had higher total cholesterol, lower high density lipoprotein, higher low density lipoprotein, higher triglycerides, and a high atherogenic index for plasma than the non-PI regimen, p = 0.001 or < 0.001. Patients on Non-PI regimens had higher mean diastolic hypertension than patients on PI regimens, p < 0.001.

CONCLUSIONS

Our finding of no differences in renal dysfunction between patients on Tenofovir and those on Non-Tenofovir containing ART regimens means that Tenofovir based first line ART can safely be initiated even in settings without routine renal function monitoring. However, integration of cardiovascular risk assessment, preventive and curative measures against cardiovascular disease are required. The CoLTART cohort is a good platform to investigate the complications of long-term ART use in Uganda.

Longitudinal Assessment of Proximal Tubular Dysfunction in HIV Seropositive and Seronegative Persons: Correlates and Implications

BACKGROUND

Proximal tubular dysfunction (PTD) is common in HIV-positive persons and has been associated with tenofovir disoproxil fumarate (TDF). However, few studies have assessed the natural history PTD in HIV-positive and -negative individuals, or the association of PTD with the subsequent trajectory of directly measured glomerular filtration rate (mGFR).

METHODS

We followed 192 HIV-positive and 100 HIV-negative, nondiabetic participants for 3 years. We measured 3 PTD markers (normoglycemic glycosuria, fractional excretion of phosphorus, and tubular proteinuria) and mGFR (by iohexol disappearance from serum) annually. We used univariate and multivariate generalized estimating equation logistic regression to identify factors associated with PTD across all visits and linear mixed effects models to assess the association between baseline PTD and mGFR slope.

RESULTS

Compared with HIV-negative participants, HIV-positive persons that were not taking antiretroviral therapy were at increased risk of PTD (adjusted odds ratio 3.33; 95% confidence interval: 1.65 to 6.71), whereas those taking a TDF-based or a TDF-sparing regimen were not at significantly increased risk of PTD. Among HIV-positive participants, uncontrolled viremia was a strong correlate of PTD. Forty-nine of 55 (89%) participants with PTD at baseline had at least 1 subsequent visit without PTD. There was no association between baseline PTD and rate of decline in mGFR over time.

CONCLUSIONS

Poorly controlled HIV may be a stronger risk factor for PTD than TDF use. The individual-level variability of the PTD markers over time was high, potentially limiting their usefulness for routine screening in unselected patients. Baseline PTD was not associated with subsequent mGFR slope.

The effect of Tenofovir on renal function among Ugandan adults on long-term antiretroviral therapy: a cross-sectional enrolment analysis

Background

WHO recommends using Tenofovir containing first line antiretroviral therapy (ART), however, Tenofovir has been reported to be associated with renal impairment and dysfunction. We compared renal function among individuals on Tenofovir and those on non-Tenofovir containing ART.

Methods

In a cross-sectional study of HIV-Positive adults on ART, at enrolment into a prospective cohort to study the long-term complications of ART in Uganda, information on biophysical measurements, medical history, clinical examination and renal function tests (RFTs) was collected. Fractional Tubular phosphate reabsorption and estimated glomerular filtration rate (eGFR) were calculated. Mean values of RFTs and proportions with abnormal RFTs were compared between non-Tenofovir containing (Non-TDF) and Tenofovir containing (TDF-ART) ART regimen groups using a general linear regression model. Durations of TDF exposure were also compared.

Results

Between July 2013 and October 2014, we enrolled 953 individuals on ART for 6 or more months, median duration on ART was 9.3 years, 385 (40.4 %) were on non-TDF and 568 (59.6 %) on TDF-ART regimens. The proportion of participants with Proteinuria (>30 mg/dl) was higher among the TDF-ART group than the non-TDF ART group. However, in multivariable analysis, there were no significant differences in the adjusted mean differences of eGFR, serum urea, serum creatinine, fractional tubular reabsorption of phosphate and serum phosphates when patients on TDF-ART were compared with those on non-TDF containing ART. There were no differences in renal function even when different durations on Tenofovir were compared.

Conclusions

We found no differences in renal function among patients on Tenofovir and non-Tenofovir containing ART for almost a decade. Tenofovir based first line ART can therefore safely be initiated even in settings without routine renal function monitoring.

Urinary Markers of Tubular Injury in HIV-Infected Patients

Renal disease is a common complication of HIV-infected patients, associated with increased risk of cardiovascular events, progression to AIDS, AIDS-defining illness, and mortality. Early and accurate identification of renal disease is therefore crucial to improve patient outcomes. The use of serum creatinine, along with proteinuria, to detect renal involvement is essentially to screen for markers of glomerular disease and may not be effective in detecting earlier stages of renal injury. Therefore, more sensitive and specific markers are needed in order to early identify HIV-infected patients at risk of renal disease. This review article summarizes some new and important urinary markers of tubular injury in HIV-infected patients and their clinical usefulness in the renal safety follow-up of TDF-treated patients.

Urinary β2 microglobulin can predict tenofovir disoproxil fumarate-related renal dysfunction in HIV-1-infected patients who initiate tenofovir disoproxil fumarate-containing antiretroviral therapy

OBJECTIVE

In nephrotoxicity induced by tenofovir disoproxil fumarate (TDF), tubular dysfunction precedes the decline in GFR, suggesting that tubular markers are more sensitive than estimated glomerular filtration rate (eGFR). The hypothesis that urinary β2 microglobulin (β2 M), a tubular function marker, can predict TDF-renal dysfunction in HIV-1-infected patients was tested.

DESIGN

A single-center observational study.

METHODS

The inclusion criteria were: HIV-1-infected patients who started TDF-containing antiretroviral therapy from 2004 to 2013, urinary β2 M after and closest to the day of TDF initiation within 180 days (termed 'β2 M after TDF') was measured. The associations between 'β2 M after TDF' and four renal end points (>10 ml/min per 1.73 m decrement in eGFR relative to baseline, >20 decrement, >25% decrement, and eGFR < 60) were estimated with logistic regression model. The association between 'β2 M after TDF' and longitudinal changes in eGFR after initiation of TDF was estimated with a mixed-model.

RESULTS

A total 655 study patients were analyzed (96% men, median age 38, median CD4 238 cells/μl, 63% treatment naïve). The median baseline eGFR was 117 ml/min per 1.73 m (IQR 110-125), and the median duration of TDF use was 3.32 years (IQR 2.02-5.31). 'β2 M after TDF' was significantly associated with more than 20 decrement in eGFR (P = 0.024) and more than 25% decrement (P = 0.014), and was marginally associated with eGFR less than 60 (P = 0.076). It was also significantly associated with the longitudinal eGFR after initiation of TDF (P < 0.0001). 'β2 M after TDF' of 1700 μg/l was identified as the optimal cutoff value for the prediction of longitudinal eGFR.

CONCLUSIONS

Urinary β2 M measured within 180 days after initiation of TDF predicts renal dysfunction related to long-term TDF use.

Tenofovir monotherapy for hepatitis B after 1 year does not produce renal dysfunction, but is associated with hyperparathyroidism not related to vitamin D

INTRODUCTION

Viral hepatitis B (VHB) represents a major public health problem. Studies from HIV multidrug patients have associated the use of tenofovir disoproxil fumarate (TDF) with renal dysfunction and phosphate wasting.

OBJECTIVE

The aim of this study was to examine the effect of year-long TDF monotherapy on renal function in VHB patients.

PATIENTS AND METHODS

We evaluated adult patients diagnosed with VHB before treatment initiation (T0), and after 3 and 12 months (T3 and T12) of TDF initiation. Estimated glomerular filtration rate (eGFR) was estimated by serum cystatin C and creatinine. In addition, urinary electrolytes and tubular biomarkers (cystatin C, β2-microglobulin and neutrophil gelatinase-associated lipocalin) were analyzed, as well as parathyroid hormone (PTH) and 25(OH)vitamin D levels.

RESULTS

After 1 year, 32 patients completed the study, 22 (68.7%) men and 12 (37.5%) Whites, mean age 44.1±12.0 years. We found that serum electrolytes were similar at baseline and 3 or 12 months after initiation of TDF monotherapy. In addition, urinary fractional excretions of electrolytes as well as proteinuria, albuminuria, urinary β2-microglobulin, and urinary cystatin C showed no significant differences across the treatment timeline. There were also no statistical differences in the eGFR. There was a statistically significant increase in the PTH (Friedman's test, P=0.012), but the 25(OH)vitamin D levels were in the normal range in the beginning and did not change at the follow-up. Moreover, there was no correlation between the initial levels of vitamin D and the corresponding increases in the PTH values.

CONCLUSION

If used as monotherapy in hepatitis B patients for a 12-month period, TDF is not associated with changes in either eGFR or a panel of urinary biomarkers. Serum and urinary electrolytes also remained unchanged. Of note, a significant increase in the PTH was found, although not related to the 25(OH)vitamin D initial status.

Effects of renal tubular dysfunction on bone in tenofovir-exposed HIV-positive patients

OBJECTIVES

Tenofovir disoproxil fumarate (TDF) may cause renal tubular dysfunction (RTD) and reduce bone mineral density (BMD). We examined the relationship between RTD and BMD in TDF-exposed HIV-positive men.

DESIGN AND METHODS

We analysed urinary retinol-binding protein/creatinine ratio (RBPCR) and fractional excretion of phosphate (FEPO4) to quantify RTD in a cross-sectional sample of randomly selected HIV-positive men at a single tertiary outpatient clinic. BMD at the lumbar spine and hip was measured by dual-energy X-ray absorptiometry. Multivariate logistic regression was used to analyse factors associated with RTD, and linear regression to examine the relationship between RTD and BMD.

RESULTS

Of 293 men (mean age 48 years, 94% White ethnicity, median TDF exposure 2.1 years), 22.5% had RBPCR-defined RTD and 12.3% had FEPO4-defined RTD. We observed a negative correlation between RBPCR and BMD at the spine (β -0.2, P = 0.002) and hip (total: β -0.1, P = 0.02; femoral neck: β -0.1, P = 0.02), but not between FePO4 and BMD. In multivariable analyses, RTD defined by more than five-fold elevations in RBPCR was associated with significantly lower BMD of the spine.

CONCLUSION

In HIV-positive patients receiving TDF-containing antiretroviral therapy, RTD was associated with lower BMD of the spine in HIV-positive men. RBPCR quantification may identify patients at increased risk of TDF-associated BMD loss.

Urine alpha1-microglobulin is a better marker for early tubular dysfunction than beta2-microglobulin among tenofovir-exposed human immunodeficiency virus-infected men who have sex with men

OBJECTIVES

Men who have sex with men are at risk of tenofovir nephrotoxicity due to its wide use in both treatment and prophylaxis for human immunodeficiency virus infection, but little is known about the urinary biomarkers of early renal dysfunction in this population. This study aims to identify useful biomarkers of early renal dysfunction among human immunodeficiency virus-infected men who have sex with men exposed to tenofovir.

METHODS

In a cross-sectional study urinary alpha1-microglobulin, beta2-microglobulin, N-acetyl-β-d-glucosaminidase and albumin were measured and expressed as the ratio-to-creatinine in 239 human immunodeficiency virus-infected men who have sex with men who were treatment naïve or receiving antiretroviral therapy with tenofovir-containing or non-tenofovir-containing regimens. Additionally, 56 patients in the non-antiretroviral therapy group started a tenofovir-containing regimen and were assessed after 3 and 6 months on antiretroviral therapy.

RESULTS

Both the frequency of alpha1-microglobulin proteinuria (alpha1-microglobulin-creatinine ratio >25.8mg/g) and the median urinary alpha1-microglobulin-creatinine ratio were higher in the tenofovir disoproxil fumarate group than the other two groups (all p<0.05). A higher frequency of beta2-microglobulin proteinuria (beta2-microglobulin-creatinine ratio >0.68mg/g) was also observed in the tenofovir group (28.9%) compared to the non-tenofovir group (13.6%, p=0.024). There were no significant differences between groups for N-acetyl-β-d-glucosaminidase and albumin. In the longitudinal study, the median urinary alpha1-microglobulin-creatinine ratio after 3 and 6 months on tenofovir-containing therapy (16.8 and 17.3mg/g) was higher than baseline (12.3mg/g, p=0.023 and 0.011, respectively), while no statistically important changes were observed in urinary beta2-microglobulin-creatinine ratio or in the other biomarkers after 3 and 6 months on antiretroviral therapy (all p>0.05).

CONCLUSION

Urinary alpha1-microglobulin seems to be a more sensitive and stable indicator of tubular dysfunction than urinary beta2-microglobulin for assessing tenofovir-related nephrotoxicity and can be significantly altered after tenofovir exposure.