Anticoagulants and acute kidney injury: clinical and pathology considerations

A comprehensive survey of warfarin-induced hepatic toxicity using histopathological, biomarker, and molecular evaluation

Warfarin finds human application as anticoagulant therapy. Warfarin usage can cause liver damage and hemorrhage. Besides functioning as anticoagulant and causing continuous bleeding of pests, the mechanism of toxicity of warfarin is unknown. In this study, Wild female and male rats were administrated orally with warfarin for 18 days at 9, 18, 27.5, and 55 mg/kg, respectively. Hepatoxicity was determined by assessing, LD50, leukocyte counts, immunochemistry, histopathology, serum proteins, Western blotting, especially of markers of liver injury, such as AST, ALT & ALP, and markers of antioxidant and oxidative stress markers. Warfarin treatment decreased Nrf2 levels while it increased caspase 3, CYP2C9, COLL1A1. It caused cellular damage and fibrosis of liver. The plasma levels of markers of liver injury, AST, ALT, ALP, bilirubin and transferrin were increased. The plasma levels of albumin, IgG and antitrypsin were decreased. Warfarin treatment decreased RBC and total lymphocyte count while increasing selectively neutrophils. Warfarin exposure caused increased oxidative stress; increased LPO and decreased GSH, SOD, CAT and NO production. Oral exposure of rats with Warfarin leads to increased oxidative stress resulting into liver damage via CYP2C9 mediated by Nrf2 depletion.

Currently Used Methods to Evaluate the Efficacy of Therapeutic Drugs and Kidney Safety

Kidney diseases with kidney failure or damage, such as chronic kidney disease (CKD) and acute kidney injury (AKI), are common clinical problems worldwide and have rapidly increased in prevalence, affecting millions of people in recent decades. A series of novel diagnostic or predictive biomarkers have been discovered over the past decade, enhancing the investigation of renal dysfunction in preclinical studies and clinical risk assessment for humans. Since multiple causes lead to renal failure, animal studies have been extensively used to identify specific disease biomarkers for understanding the potential targets and nephropathy events in therapeutic insights into disease progression. Mice are the most commonly used model to investigate the mechanism of human nephropathy, and the current alternative methods, including in vitro and in silico models, can offer quicker, cheaper, and more effective methods to avoid or reduce the unethical procedures of animal usage. This review provides modern approaches, including animal and nonanimal assays, that can be applied to study chronic nonclinical safety. These specific situations could be utilized in nonclinical or clinical drug development to provide information on kidney disease.

RecQ dysfunction contributes to social and depressive-like behavior and affects aldolase activity in mice

RecQ helicase family proteins play vital roles in maintaining genome stability, including DNA replication, recombination, and DNA repair. In human cells, there are five RecQ helicases: RECQL1, Bloom syndrome (BLM), Werner syndrome (WRN), RECQL4, and RECQL5. Dysfunction or absence of RecQ proteins is associated with genetic disorders, tumorigenesis, premature aging, and neurodegeneration. The biochemical and biological roles of RecQ helicases are rather well established, however, there is no systematic study comparing the behavioral changes among various RecQ-deficient mice including consequences of exposure to DNA damage. Here, we investigated the effects of ionizing irradiation (IR) on three RecQ-deficient mouse models (RecQ1, WRN and RecQ4). We find abnormal cognitive behavior in RecQ-deficient mice in the absence of IR. Interestingly, RecQ dysfunction impairs social ability and induces depressive-like behavior in mice after a single exposure to IR, suggesting that RecQ proteins play roles in mood and cognition behavior. Further, transcriptomic and metabolomic analyses revealed significant alterations in RecQ-deficient mice, especially after IR exposure. In particular, pathways related to neuronal and microglial functions, DNA damage repair, cell cycle, and reactive oxygen responses were downregulated in the RecQ4 and WRN mice. In addition, increased DNA damage responses were found in RecQ-deficient mice. Notably, two genes, Aldolase Fructose-Bisphosphate B (Aldob) and NADPH Oxidase 4 (Nox4), were differentially expressed in RecQ-deficient mice. Our findings suggest that RecQ dysfunction contributes to social and depressive-like behaviors in mice, and that aldolase activity may be associated with these changes, representing a potential therapeutic target.

Anticoagulant-related nephropathy induced by direct-acting oral anticoagulants: Clinical characteristics, treatments and outcomes

INTRODUCTION

There is a scarcity of data on anticoagulation-related nephropathy (ARN) caused by direct-acting oral anticoagulants (DOACs) in recent years.

MATERIALS AND METHODS

We collected literatures on DOACs-induced ARN to October 1, 2022, without language restrictions for retrospective analysis.

RESULTS

Twenty events were included with a median onset time of 28 days among which fourteen were caused by dabigatran. Patients accompanied by chronic kidney disease (85 %) seemed more easily to have an ARN. Clinical symptoms associated with ARN were mostly presented as hematuria and acute decline of renal function (100 %), then abnormal coagulation function (75 %) but only one with an INR over 3. Renal biopsies were performed in 14 patients, with thirteen showing occlusive intratubular red blood cell casts and ten showing acute tubular injury of varying intensity or even tubular necrosis. Extensive changes in interstitial compartment like hemorrhage, fibrosis or inflammation were also presented in eight biopsies. IgA nephropathy as a latent or undiagnosed disease was demonstrated in eight biopsies. Treatments of ARN were mainly supportive with all patients discontinuing DOACs and 35 % initiating dialysis for acute deterioration of renal function. Steroids were used in 9 patients with a severe ARN verified by biopsy. 60 % of patients did not recover baseline renal function and some even deteriorated.

CONCLUSIONS

In conclusion, DOACs-induced ARN is a rare but serious adverse reaction. A prompt diagnosis of ARN and supportive treatments are necessary for patients receiving DOACs concurrent with an acute renal injury.

The Rise and Fall of Antithrombin Supplementation in Cardiac Surgery

Various cohort studies, both retrospective and prospective, showed that low antithrombin levels after cardiac surgery (at the arrival in the intensive care unit and during the next days) were associated with a number of adverse outcomes, including surgical reexploration and thromboembolic events, eventually leading to prolonged stay in the intensive care. Values lower than 58% to 64% of antithrombin activity were indicative of this higher morbidity with good sensitivity and specificity. The scenario generated the hypothesis that low antithrombin levels needed to be corrected by supplementation to improve postoperative outcome. However, randomized controlled studies run to test this idea failed to demonstrate any benefit of antithrombin supplementation, showing no effects on outcome, neither as preemptive preoperative strategy nor for treating postoperative low antithrombin values. In addition, randomized trials highlighted that those patients who received antithrombin experienced significantly higher incidence of acute kidney injury with a pooled odds ratio of 4.41 (95% CI, 1.90-10.23; P = .001). A strongly decreased thrombin activity after antithrombin correction may eventually affect the efficiency of the glomerular filtration and cause the deterioration of kidney function, but underlying biological mechanisms remain unclear. In conclusion, low levels of antithrombin activity after cardiac surgery should be considered as a marker of greater severity of the patient's conditions and/or of the complexity of the surgical procedure. There are no indications for antithrombin supplementation in cardiac surgery unless for correcting heparin resistance.

Acute Kidney Injury in Patients with Non-Valvular Atrial Fibrillation Treated with Rivaroxaban or Warfarin: A Population-Based Study from the United Kingdom

Purpose

To compare the risk of acute kidney injury (AKI) among users of rivaroxaban vs warfarin.

Patients and Methods

We identified two cohorts of patients with non-valvular atrial fibrillation (NVAF) who initiated rivaroxaban (15/20 mg/day, N = 6436) or warfarin (N = 7129) excluding those without estimated glomerular filtration rate values recorded in the year before oral anticoagulant (OAC) initiation and those with a history of end-stage renal disease or AKI. We used two methods to define AKI during follow-up (mean 2.5 years): coded entries (method A) and the Aberdeen AKI phenotyping algorithm (method B) using recorded renal function laboratory values during the study period to identify a sudden renal deterioration event. Cox regression was used to calculate hazard ratios (HRs) for AKI with rivaroxaban vs warfarin use, adjusted for confounders.

Results

The number of identified incident AKI cases was 249 (method A) and 723 (method B). Of the latter, 104 (14.4%) were also identified by method A. After adjusting for age, sex, baseline renal function and comorbidity, HRs (95% CIs) for AKI were 1.19 (0.92-1.54; p=0.18) using method A and 0.80 (0.68-0.93; p<0.01) using method B. Estimates stratified by baseline level of chronic kidney disease were largely consistent with the main estimates.

Conclusion

Our results support a beneficial effect of rivaroxaban over warfarin in terms of AKI occurrence in patients with NVAF. More research into how best to define AKI using primary care records would be valuable for future studies.

Drug-Related Problems and Factors Involved in the Imbalance of Oral Anticoagulants in Lebanese Patients: A Cross-Sectional Study

The goal of this study was to identify drug-related problems (DRPs) and the factors involved in the imbalance of new oral anticoagulants (NOACs) and vitamin K antagonists in a Lebanese adult population with cardiovascular diseases. An imbalance in the hemostatic systems between procoagulant and anticoagulant factors in circulating blood produces either hemorrhagic or thrombotic conditions. A prospective cross-sectional study was conducted during 5 months in a teaching hospital. All patients at least 18 years of age taking oral anticoagulants were included in the study. A standardized questionnaire was used, and information was obtained from the patients’ profiles and electronic medical records. DRPs were identified and categorized according to the Pharmaceutical Care Network Europe classification system. A total of 258 patients were included. The overall prevalence of DRPs was 87.2%; the highest prevalence was observed in patients taking acenocoumarol (96.0%), in contrast to 76.7% and 59.0% in patients taking dabigatran and rivaroxaban, respectively. Drug interaction was the most frequent DRP (83.3%), followed by inappropriate monitoring (42.6%) and excessive dose (26.7%). Having renal disease, and taking proton-pump inhibitors or nonsteroidal anti-inflammatory drugs were among the factors affecting the international normalized ratio (INR) range (adjusted odds ratio [ORa] = 2.513, 95% confidence interval [CI] 1.238, 5.101; ORa = 2.487, 95% CI 1.139, 5.430 and ORa = 2.114, 95% CI 1.043, 4.286, respectively), whereas smoking and renal disease significantly affected activated partial thromboplastin time (aPTT) (ORa = 8.325, 95% CI 1.577, 43.965 and ORa = 6.922, 95% CI 1.471, 32.570, respectively). Patients taking NOACs had greater aPTT control and fewer DRPs, with a wide therapeutic index enabling administration of fixed doses.

Simultaneous subacute interstitial nephritis and anticoagulant-related nephropathy related to novel oral anticoagulants use

Introduction: Interstitial nephritis related to novel oral anticoagulants was only reported in sporadic case reports and none was accompanied by anticoagulants related nephropathy (ARN).Case Report: We presented here a case of biopsy-proven subacute interstitial nephritis (SubAIN) accompanied by ARN after oral dabigatran to alarm clinicians. This case manifested with gross hematuria, acute kidney injury, slightly prolonged thrombin time, moderate anemia, moderate proteinuria, a large quantity of intratubular hemoglobin casts confirmed by hemoglobin antibody immunohistochemical staining which presumed to occur around 1 week after dabigatran and subacute interstitial nephritis accompanied by focal proliferative glomerulonephritis. Serum creatinine level did not continue to elevate after discontinuation of the oral anticoagulant. With the subsequent supportive therapy, it decreased to some extent then reduced to normal with the help of prednisone (half of the full dose).Conclusions: When we came across a patient who manifested as hematuria or acute kidney injury with a history of anticoagulants usage, we should think of ARN and pay more attention on history collection. Secondly, subacute interstitial nephritis may coexist with ARN. Thirdly, hemoglobin immunohistochemical staining may be helpful to make it clear whether the intra-tubular protein casts came from red blood cells. In addition, for those patients who may have decreased kidney function, anticoagulants dose should be reduced to prevent the occurrence of ARN.

IgA nephropathy is the most common underlying disease in patients with anticoagulant-related nephropathy

Introduction

Anticoagulant-related nephropathy (ARN) is a relatively novel recognized entity characterized by hematuria-associated acute kidney injury (AKI) in the context of overanticoagulation. Preexisting or underlying kidney disease seems to be a predisposing factor; however, few studies have described histologic findings in patients with ARN. We aimed to evaluate underlying kidney pathology in patients on oral anticoagulation who presented an episode of AKI with hematuria in whom a kidney biopsy was performed.

Methods

Retrospective observational multicenter case study in patients treated with oral anticoagulants who developed macroscopic or intense hematuria followed by AKI. Only patients with available kidney biopsy specimens were included. Histologic findings and clinical data throughout follow-up were analyzed.

Results

A total of 26 patients were included with a median age of 75 years (62–80) and a follow-up period of 10.1 months. Of the patients, 80% were male, and most cases (92%) were on anticoagulation with vitamin K antagonists (VKAs). At admission, median serum creatinine (SCr) level was 4.2 mg/dl (2.8–8.2), median international normalized ratio (INR) 2.4 (1.5–3.4), and 11 patients (42%) required acute dialysis during hospitalization. Kidney biopsy results revealed that all patients except 1 had an underlying nephropathy: IgA nephropathy (IgAN) in 19, probable IgAN in 1, diabetic nephropathy in 3, nephrosclerosis in 1, and idiopathic nodular glomerulosclerosis in 1. At 12 weeks after discharge, only 6 subjects (24%) attained complete kidney recovery whereas 7 (28%) remained on chronic dialysis.

Conclusion

IgAN was the most common underlying kidney disease in our biopsy-proven series of ARN, in which a significant percentage of patients did not achieve kidney function recovery.

The impact on renal function after long-term use of anticoagulants in atrial fibrillation patients

OBJECTIVE

Long-term oral anticoagulant should be considered or recommended in patients with atrial fibrillation (AF) and CHA2DS2VASc score ≥ 1 for stroke prevention. Warfarin and different direct oral anticoagulants (DOACs) are metabolized differently by the kidney. The impact on renal function after long-term use of anticoagulants in the patients with AF remains unclear. This study aimed to compare DOACs and warfarin's impact on the decline in renal function from a large cohort with AF.

METHODS

This study included patients with nonvalvular AF from 2000 to 2018, mainly through the medical history (ICD code) of the Chang Gung Research Database. Baseline estimated glomerular filtration rate (eGFR), follow-up eGFR and the change in eGFR between 2-year eGFR and baseline eGFR were compared between different DOACs and warfarin after propensity score matching. The primary study endpoint was acute kidney injury (AKI).

RESULTS

3657 patients were enrolled in this study and the mean observation time was 3.3 ± 0.9 years. During the observation period, there was a significantly higher incidence of AKI during follow-up in the warfarin group than in the different DOAC groups before and after propensity score matching (before: warfarin vs. DOAC: 9.2% vs. 5.2%, p <  0.001; after: warfarin vs. DOAC: 8.9% vs. 4.4%, p <  0.001). There was no difference in the incidence of AKI between dabigatran group and anti-factor Xa inhibitor group after propensity score matching. The incidence of AKI was similar among rivaroxaban, apixaban and edoxaban groups after propensity score matching. The change in eGFR between 2-year eGFR and baseline eGFR did not differ between the warfarin and DOAC groups after propensity score matching (warfarin vs. DOAC: - 1.27 ± 20.32 vs. -1.94 ± 17.24 mL/min/1.73 m2, p = 0.461).

CONCLUSIONS

During the mean observation time of 3.3 ± 0.9 years, warfarin was associated with a higher incidence of AKI compared with DOACs. The decline in renal function did not differ among warfarin and different DOAC groups.

Dabigatran-Induced Nephropathy and Gastrointestinal Bleeding and Its Successful Treatment with Idarucizumab: A Case Report

Recently, the atrial fibrillation treatment guidelines have been updated to now recommend Non-vitamin K antagonist oral anticoagulants (NOACs) as the preferred alternative to warfarin for systemic embolism and stroke prevention in patients with non-valvular atrial fibrillation. NOACs have major pharmacologic advantages over warfarin, although the most common complications are gastrointestinal bleeding and NOAC-induced nephropathy within 6 weeks after starting therapy, as several recent case-reports stated. We are reporting for the first time a chronic delayed adverse reaction (regularly reported to Authorities) observed in an 82-year-old woman 27 months after starting dabigatran (110 mg twice a day), characterized by concomitant gastrointestinal bleeding and nephropathy. Idarucizumab administration immediately improved both bleeding and renal parameters. Moreover, we are going to highlight the importance of the compliance, the adherence to the therapeutic plan and the supervision of the Hospital Pharmacy on drug prescriptions. In fact in our case, dabigatran was firstly prescribed by the neurologist and delivered by the hospital pharmacy, but the patient continued the treatment for 27 months, prescribed by general practitioner without any laboratory control. This lack of supervision certainly contributed to the onset of the adverse reaction reported.

Management of Anticoagulant-Related Nephropathy: A Single Center Experience

BACKGROUND

Anticoagulant-related nephropathy (ARN) is a form of acute kidney injury that mainly occurs in patients with previously unrecognized glomerular disease in addition to excessive anticoagulation. Since a renal biopsy is not performed in most cases, the diagnosis is often presumptive.

METHODS

Here, we present the characteristics of a national Slovenian patient cohort with histologically verified ARN, from the first case in 2014 to December 2020, and a review of the current literature (Pubmed database).

RESULTS

In Slovenia, ARN has been detected in 13 patients, seven of whom were treated with coumarins, and others with direct oral anticoagulants. In seven patients, ARN appeared after excessive anticoagulation. As many as 11 patients had underlying IgA nephropathy. Similar to the global data presented here, the pathohistological impairment associated with pre-existing glomerulopathy was mild and disproportionate to the degree of functional renal impairment. The majority of our patients with ARN experienced severe deterioration of renal function associated with histological signs of accompanying acute tubular injury, interstitial edema, and occlusive red blood cell casts. These patients were treated with corticosteroids, which (in addition to supportive treatment and discontinuation of the anticoagulant drug) led to a further improvement in renal function.

CONCLUSIONS

Anticoagulant therapy combined with a pre-existing glomerular injury may lead to ARN. In addition to discontinuation of the anticoagulant and supportive care, corticosteroids, which are currently listed in only a few cases in the world literature, may have a positive influence on the course of treatment. However, the benefits of steroid treatment must be weighed against the risk of complications, especially life-threatening infections.

Acute Renal Failure in a Patient with Rivaroxaban-Induced Hypersensitivity Syndrome: A Case Report with a Review of the Literature and of Pharmacovigilance Registries

Direct oral anticoagulants (DOACs) are among the most commonly prescribed medications, and DOAC-associated kidney dysfunction may be a problem that is underrecognized by clinicians. We report on the case of an 82-year-old patient who, two weeks after the prescription of rivaroxaban for atrial fibrillation, was hospitalized for a drug-induced hypersensitivity syndrome whose main clinical manifestations were low-grade fever with a petechial rash in the legs and acute renal failure (ARF). Within one week after rivaroxaban withdrawal, the patient's clinical condition improved and the renal function normalized. In a review of the literature, we only found five case reports of rivaroxaban-related ARF: two patients had tubulo-interstitial nephritis (TIN), two had anticoagulant-related nephropathy (ARN), and the last one had IgA nephropathy. As some recent publications suggest that kidney injury due to anticoagulation drugs may be largely underdiagnosed, we also analyzed the data from the VigiAccess database, the World Health Organization pharmacovigilance program that collects drug-related adverse events from 134 national registries worldwide. Among all the rivaroxaban-associated adverse events reported in VigiAccess since 2006, 4,323 (3.5%) were renal side effects, of which 2,351 (54.3%) were due to unspecified ARF, 363 (8.4%) were due to renal hemorrhage (characteristically associated with ARN), and 24 (0.6%) were due to TIN. We also compared these results with those reported in VigiAccess for other DOACs and vitamin K antagonists. This analysis suggests that the frequency of renal adverse events associated with rivaroxaban and other DOACs may be appreciably higher than what one might currently consider based only on the small number of fully published cases.

Drug-induced tubulointerstitial nephritis: hypersensitivity and necroinflammatory pathways

More than 250 drugs carry a small but important dose-independent risk of initiating a delayed-type hypersensitivity reaction that leads to acute tubulointerstitial nephritis (TIN). Clinical manifestations are often non-specific, making epidemiological studies challenging. In severe cases, if cessation of the offending drug is not followed by a prompt improvement in renal function, corticosteroid therapy appears to enhance renal recovery rates. Other drugs, classified as potential nephrotoxins, may induce dose-dependent acute tubular necrosis. Studies over the past decade have identified a unique form of tubular cell death called "necroptosis" that is accompanied by a specific and significant interstitial inflammatory response to certain insults, including some nephrotoxins. Insights into the molecular basis of this necroinflammatory pathway have emerged. There is still a paucity of pediatric data on these two distinct types of drug-induced TIN. Early recognition is essential to minimize the risk of chronic kidney damage.

Calcitriol Ameliorates Kidney Injury Through Reducing Podocytopathy, Tubular Injury, Inflammation and Fibrosis in 5/6 Subtotal Nephrectomy Model in Rats

Chronic kidney diseases (CKDs) lead to end-stage renal diseases (ESRD) which are characterized by glomerulosclerosis, tubular injury, anemia, inflammation, and interstitial fibrosis. Vitamin D is known to have renal protective effects. However, its effects relate to low and high doses of Vitamin D in CKD model is still unknown. CKD was performed using 5/6 subtotal nephrectomy procedure in male Sprague Dawley rats (3 months old, 200-300 grams, SN group; n=6), then rats were sacrificed on day 14 after operation. Sham operation was used for control (SO group; n=6). Calcitriol was administered in two doses : 0.01 µg/mL/100 gramsBW/day (SND1 group; n=6) and 0.05 µg/mL/100 gramsBW/day (SND2 group; n=6) intraperitoneally for 14 days. Glomerulosclerosis and tubular injury score were examined using PAS staining, meanwhile, interstitial fibrosis area fraction was assessed with Sirius Red staining. RT-PCR was performed for assessing nephrin, podocin, IL-6, CD68, Collagen-1, and TGF-β1 mRNA expressions. Immunostaining (IHC) was carried out to observe macrophage (CD68) and myofibroblast (α-SMA). SN demonstrated CKD condition with higher tubular injury, glomerulosclerosis, interstitial fibrosis, and inflammation compared to SO. Calcitriol-treated group (especially SND2) demonstrated significant lower tubular injury, glomerulosclerosis, and interstitial fibrosis compared to SN. SND2 group showed not only significantly lower CD68, IL-6, Collagen-1, and TGF-β1 mRNA expressions, but also higher mRNA expressions of nephrin and podocin. SND2 group also demonstrated reduction of macrophages infiltration and myofibroblasts expansion based on its histopathological appearance. Vitamin D may have a renoprotective effect on 5/6 subtotal nephrectomy model by attenuating podocytopathy, tubular injury, inflammation and interstitial fibrosis.

Kidney-based in vitro models for drug-induced toxicity testing

The kidney is frequently involved in adverse effects caused by exposure to foreign compounds, including drugs. An early prediction of those effects is crucial for allowing novel, safe drugs entering the market. Yet, in current pharmacotherapy, drug-induced nephrotoxicity accounts for up to 25% of the reported serious adverse effects, of which one-third is attributed to antimicrobials use. Adverse drug effects can be due to direct toxicity, for instance as a result of kidney-specific determinants, or indirectly by, e.g., vascular effects or crystals deposition. Currently used in vitro assays do not adequately predict in vivo observed effects, predominantly due to an inadequate preservation of the organs' microenvironment in the models applied. The kidney is highly complex, composed of a filter unit and a tubular segment, together containing over 20 different cell types. The tubular epithelium is highly polarized, and the maintenance of this polarity is critical for optimal functioning and response to environmental signals. Cell polarity is dependent on communication between cells, which includes paracrine and autocrine signals, as well as biomechanic and chemotactic processes. These processes all influence kidney cell proliferation, migration, and differentiation. For drug disposition studies, this microenvironment is essential for prediction of toxic responses. This review provides an overview of drug-induced injuries to the kidney, details on relevant and translational biomarkers, and advances in 3D cultures of human renal cells, including organoids and kidney-on-a-chip platforms.

Deconstructing the Pharmacovigilance Hype Cycle

Data science is making increasing contributions to pharmacovigilance. Although the technical innovation of these works are indisputable, efficient progress in real-world pharmacovigilance signal detection may be hampered by corresponding technology life cycle effects, with a resulting tendency to conclude that, with large enough datasets and intricate algorithms, "the numbers speak for themselves," discounting the importance of clinical and scientific judgment. A practical consequence is overzealous declarations regarding the safety or lack of safety of drugs. We describe these concerns through a critical discussion of key results and conclusions from case studies selected to illustrate these points.

Direct oral anticoagulant and AKI: apixaban-induced acute interstitial nephritis

Direct oral anticoagulants (DOACs)-dabigatran, rivaroxaban, apixaban and edoxaban-are changing the landscape of clinical practice for patients requiring short and long-term anticoagulation. We report a patient with no history of kidney disease developing acute interstitial nephritis (AIN) after starting a DOAC, apixaban. To date, this is the first biopsy proven case of apixaban-induced AIN.

Oral Anticoagulation in Patients With End-Stage Kidney Disease on Dialysis and Atrial Fibrillation

Patients with end-stage kidney disease (ESKD) have an elevated incidence of atrial fibrillation (AF) and are at increased risk for thromboembolic events. However, these patients are also at increased risk for bleeding and it is unclear whether they benefit from an oral anticoagulant. Point prevalent on July 1, 2015, only ~28% of dialysis patients with AF were on oral anticoagulation. Warfarin was the most commonly used oral anticoagulant, followed by apixaban, while dabigatran and rivaroxaban were rarely used. This article reviews the current evidence regarding each oral anticoagulant especially as they relate to patients with ESKD.

Anticoagulant-related nephropathy: systematic review and meta-analysis

Background

The aim of this study was to report the prevalence and mortality associated with anticoagulant-related nephropathy (ARN) through a systematic review of the literature.

Methods

Electronic searches were conducted in the Medline and EMBASE databases, and manual searches were performed in the reference lists of the identified studies. The studies were selected by two independent researchers, first by evaluating the titles and abstracts and then by reading the complete texts of the identified studies. Case series, cross-sectional studies, cohort studies and case–control studies reporting the prevalence and factors associated with ARN were selected. The methodological quality was assessed using the Newcastle–Ottawa scale. Meta-analyses of the prevalence of ARN and 5-year mortality using the random effects model were performed when possible. Heterogeneity was assessed using the I² statistic.

Results

Five studies were included. Prevalence of ARN ranged from 19% to 63% among the four included cohort studies. Meta-analysis of these resulted in high heterogeneity [I² 96%, summary effect 31%; 95% confidence interval (CI) 22–42%]. Subgroup meta-analysis yielded an ARN prevalence of 20% among studies that included patients with fewer comorbidities (I² 12%; 95% CI 19–22%). In a direct comparison, meta-analysis of the 5-year mortality rate between anticoagulated patients who had experienced ARN and anticoagulated patients without ARN, patients with ARN were 91% more likely to die (risk ratio = 1.91; 95% CI 1.22–3; I² 87%). Risk factors for ARN that were reported in the literature included initial excessive anticoagulation, chronic kidney disease, age, diabetes, hypertension, cardiovascular disease and heart failure.

Conclusions

ARN studies are scarce and heterogeneous, and present significant methodological limitations. The high prevalence of ARN reported herein suggests that this entity is underdiagnosed in clinical practice. Mortality in patients with ARN seems to be high compared with patients without this condition in observational studies.

Defining Minimum Necessary Anticoagulation-Related Communication at Discharge: Consensus of the Care Transitions Task Force of the New York State Anticoagulation Coalition

BACKGROUND

Anticoagulated patients are particularly vulnerable to ADEs when they experience changes in medical acuity, pharmacotherapy, or care setting, and resources guiding care transitions are lacking. The New York State Anticoagulation Coalition convened a task force to develop a consensus list of requisite data elements (RDEs) that should accompany all anticoagulated patients undergoing care transitions.

METHODS

A multidisciplinary panel of 15 anticoagulation experts voluntarily completed an iterative Delphi process. Resources were disseminated and deliberated via remote technology, with consensus achieved via blinded electronic polling.

RESULTS

The panel reached consensus on a list of 15 RDEs for anticoagulation communication at discharge (the ACDC List). Consensus was rapidly achieved by the full panel on 13 elements, while 3 (2 of which were combined into 1 element) required multiple iterations and achieved consensus with votes from 8 available panelists. The elements encompassed a range of factors, including drug use and indications, previous exposure and duration of therapy, recent drug exposure and laboratory results and expectations for subsequent administration, therapy goals, patient education and comprehension, and expectations for clinical management. Twelve of the elements are applicable to any anticoagulant, and 3 are specific to warfarin.

CONCLUSION

The ACDC List identifies specific pieces of clinical information that a panel of anticoagulant experts agree should be communicated to downstream providers for all anticoagulated patients undergoing care transitions. Additional study is needed to objectively evaluate the ability of existing care systems to communicate the elements and to assess possible relationships between communication of the elements and clinical outcomes.

Kidney disease models: tools to identify mechanisms and potential therapeutic targets

Acute kidney injury (AKI) and chronic kidney disease (CKD) are worldwide public health problems affecting millions of people and have rapidly increased in prevalence in recent years. Due to the multiple causes of renal failure, many animal models have been developed to advance our understanding of human nephropathy. Among these experimental models, rodents have been extensively used to enable mechanistic understanding of kidney disease induction and progression, as well as to identify potential targets for therapy. In this review, we discuss AKI models induced by surgical operation and drugs or toxins, as well as a variety of CKD models (mainly genetically modified mouse models). Results from recent and ongoing clinical trials and conceptual advances derived from animal models are also explored.

Warfarin-related nephropathy with acute kidney injury in a patient with immunoglobulin A nephropathy

A 55-year-old man with Marfan syndrome taking warfarin for anticoagulant therapy after aortic valve replacement developed acute kidney injury (serum creatinine level of 9.01 mg/dL) and gross macrohematuria. Renal biopsy showed red cell casts in the renal tubules, glomerular crescent formation in the glomeruli with immunoglobulin A deposition, and global sclerosis. Based on these findings, the patient was diagnosed with warfarin-related nephropathy with acute kidney injury characterized by immunoglobulin A nephropathy with crescents. The warfarin was withdrawn, and his hematuria and renal function improved without immunosuppressive agents.

Acenocoumarol as an alternative anticoagulant in a patient with warfarin-related nephropathy

ADVERSE EVENT

Warfarin-related nephropathy.

DRUG IMPLICATED

Warfarin.

THE PATIENT

A 31-year-old female, managed with warfarin for rheumatic heart disease with atrial fibrillation.

EVIDENCE THAT LINKS THE DRUG TO THE EVENT

There were no alternative causes of nephropathy that could have caused the adverse event in this patient.

MANAGEMENT

Shifting the drug from warfarin to acenocoumarol.

MECHANISM

Difference in renal elimination between warfarin and acenocoumarol.

IMPLICATION FOR THERAPY

Clinicians should be aware of this rare adverse effect of warfarin, and acenocoumarol can be considered as an alternative therapy for this condition.

HYPOTHESES TO BE TESTED

Further prospectively designed studies are needed to consider acenocoumarol as an alternative therapy in warfarin-related nephropathy.

Warfarin-related nephropathy in a patient with renal pelvic cancer

An 83-year-old Japanese man had a history of chronic heart failure due to bradycardia-tachycardia syndrome. He was admitted to our hospital because of macrohematuria and acute kidney injury (AKI), which were detected by an urologist at an outpatient visit. He had a history of recurrent macrohematuria and transurethral resection of bladder tumors twice in the preceding 2 years. He had been on warfarin for 12 years, with a stable international normalized ratio (INR) that was usually less than 2.1. Urinalysis revealed numerous red blood cells (RBCs) and mild proteinuria without RBC casts. His serum creatinine level was elevated to 2.41 mg/dL from 0.96 mg/dL at 3 weeks before admission. INR was 1.44. Hydronephrosis was not observed. Ureteroscopy detected invasive urothelial carcinoma of the renal pelvis, and right laparoscopic nephroureterectomy was performed at 41 days after diagnosis of AKI. The background renal parenchyma displayed tubular obstruction by red blood cell casts and acute tubular injury, which were changes compatible with warfarin-related nephropathy (WRN). Warfarin was discontinued, and the serum creatinine level recovered to 1.66 mg/dL after 3 months. In the present patient with nephrosclerosis, WRN occurred at a therapeutic INR level after 12 years of uneventful warfarin therapy, and the coexisting urothelial malignancy was a unique feature.

Novel oral anticoagulant and kidney injury: apixaban-related acute interstitial nephritis

Non-vitamin K oral anticoagulants (NOACs) are being increasingly prescribed. These drugs act rapidly, have predictable dose-related anticoagulation effect and require no routine laboratory monitoring, making them attractive for both patients and healthcare providers. All NOACs are at least partially excreted thought the kidneys. Renal injury related to NOAC use is being increasingly reported. NOAC-related acute interstitial nephritis (AIN) has only been reported once and that was in context of dabigatran use. We describe the first case of apixaban-related AIN. This case adds an important differential diagnoses that should be considered for any patient presenting with renal injury while being treated with NOACs.

Oral anticoagulants and risk of nephropathy

Anticoagulant-related nephropathy, a recently recognized entity, manifests as unexplained acute kidney injury in the setting of excessive anticoagulation with oral agents. Histologic findings in warfarin-related nephropathy include glomerular hemorrhage and renal tubular obstruction by red blood cells. Affected patients are at increased risk of mortality as well as irreversible kidney injury. Patients with chronic kidney disease are particularly vulnerable to this complication. Similar case reports of anticoagulant-related nephropathy have been linked to the more novel oral anticoagulant, dabigatran. Anticoagulant-related nephropathy has been successfully reproduced in rat models. These animal models shed light on the pathogenesis of the disease including the potential role of direct thrombin and protease-activated receptor-1 inhibition. Warfarin and dabigatran also cause an increase in systolic blood pressure in rats, a risk factor for developing nephropathy. This article reviews the current evidence for anticoagulant-related nephropathy and provides data for the suggested possible mechanisms underlying this adverse effect.