Haematuria and acute kidney injury in elderly patients admitted to hospital with supratherapeutic warfarin anticoagulation

Mortality prediction and influencing factors for intensive care unit patients with acute tubular necrosis: random survival forest and cox regression analysis

Background: Patients with acute tubular necrosis (ATN) not only have severe renal failure, but also have many comorbidities, which can be life-threatening and require timely treatment. Identifying the influencing factors of ATN and taking appropriate interventions can effectively shorten the duration of the disease to reduce mortality and improve patient prognosis. Methods: Mortality prediction models were constructed by using the random survival forest (RSF) algorithm and the Cox regression. Next, the performance of both models was assessed by the out-of-bag (OOB) error rate, the integrated brier score, the prediction error curve, and area under the curve (AUC) at 30, 60 and 90 days. Finally, the optimal prediction model was selected and the decision curve analysis and nomogram were established. Results: RSF model was constructed under the optimal combination of parameters (mtry = 10, nodesize = 88). Vasopressors, international normalized ratio (INR)_min, chloride_max, base excess_min, bicarbonate_max, anion gap_min, and metastatic solid tumor were identified as risk factors that had strong influence on mortality in ATN patients. Uni-variate and multivariate regression analyses were used to establish the Cox regression model. Nor-epinephrine, vasopressors, INR_min, severe liver disease, and metastatic solid tumor were identified as important risk factors. The discrimination and calibration ability of both predictive models were demonstrated by the OOB error rate and the integrated brier score. However, the prediction error curve of Cox regression model was consistently lower than that of RSF model, indicating that Cox regression model was more stable and reliable. Then, Cox regression model was also more accurate in predicting mortality of ATN patients based on the AUC at different time points (30, 60 and 90 days). The analysis of decision curve analysis shows that the net benefit range of Cox regression model at different time points is large, indicating that the model has good clinical effectiveness. Finally, a nomogram predicting the risk of death was created based on Cox model. Conclusion: The Cox regression model is superior to the RSF algorithm model in predicting mortality of patients with ATN. Moreover, the model has certain clinical utility, which can provide clinicians with some reference basis in the treatment of ATN and contribute to improve patient prognosis.

Acute Kidney Injury in Different Anticoagulation Strategies: A Large-Scale Pharmacoepidemiologic Study Using Real-World Data

PURPOSE

Acute kidney injury (AKI) following anticoagulant application has received growing attention as a significant emerging complication of anticoagulation. Nevertheless, there remains a lack of real-world studies to compare the incidence, clinical features, and prognosis of AKI across different anticoagulant regimens.

METHODS

Disproportionality analysis and Bayesian analysis were used to identify suspected AKI cases after different anticoagulant use within the Food and Drug Administration's Adverse Event Reporting System from January 2004 to March 2023. The time to onset, fatality, and hospitalization rates of anticoagulant-associated AKI were also investigated.

RESULTS

We identified 9313 anticoagulant-associated AKIs, which appeared to influence mostly patients over 65 years old (65.37%). Lepirudin displayed a stronger AKI association than others, based on the highest reporting odds ratio (ROR = 6.66, 95% CI = 3.97-11.18), proportional reporting ratio (PRR = 6.08, χ2 = 69.12), and empirical Bayes geometric mean (EBGM = 6.08, the lower 90% one-sided CI = 3.95). Warfarin showed the slightest association with AKI in oral anticoagulants, lower than any direct oral anticoagulants excluding apixaban. Edoxaban exhibited the highest potential renal risk among direct oral anticoagulants, with an ROR of 3.32 (95% CI = 2.95-3.72). The median time to AKI onset was 36 (IQR 7-205) days following the initiation of anticoagulation therapy, and most AKI cases occurred within the first month.

CONCLUSION

Particular attention should be directed toward monitoring renal function in individuals receiving anticoagulants, including warfarin and direct oral anticoagulants, as well as other anticoagulant agents. This diligence is particularly imperative within the first month after anticoagulant administration for individuals with a tendency for AKI.

The association between warfarin usage and international normalized ratio increase: systematic analysis of FDA Adverse Event Reporting System (FAERS)

Introduction

Elevated international normalized ratio (INR) has been commonly reported as an adverse drug event (ADE) for patients taking warfarin for anticoagulant therapy.

Aim

The purpose of this study was to determine the association between increased INR and the usage of warfarin by using the pharmacovigilance data from the FDA Adverse Event Reporting System (FAERS).

Methods

The ADEs in patients who took warfarin (N = 77,010) were analyzed using FAERS data. Association rule mining was applied to identify warfarin-related ADEs that were most associated with elevated INR (n = 15,091) as well as possible drug-drug interactions (DDIs) associated with increased INR. Lift values were used to identify ADEs that were most commonly reported alongside elevated INR based on the correlation between both item sets. In addition, this study sought to determine if the increased INR risk was influenced by sex, age, temporal distribution, and geographic distribution and were reported as reporting odds ratios (RORs).

Results

The top 5 ADEs most associated with increased INR in patients taking warfarin were decreased hemoglobin (lift = 2.31), drug interactions (lift = 1.88), hematuria (lift = 1.58), asthenia (lift = 1.44), and fall (lift = 1.32). INR risk increased as age increased, with individuals older than 80 having a 63% greater likelihood of elevated INR compared to those younger than 50. Males were 9% more likely to report increased INR as an ADE compared to females. Individuals taking warfarin concomitantly with at least one other drug were 43% more likely to report increased INR. The top 5 most frequently identified DDIs in patients taking warfarin and presenting with elevated INR were acetaminophen (lift = 1.81), ramipril (lift = 1.71), furosemide (lift = 1.64), bisoprolol (lift = 1.58), and simvastatin (lift = 1.58).

Conclusion

The risk of elevated INR increased as patient age increased, particularly among those older than 80. Elevated INR frequently co-presented with decreased hemoglobin, drug interactions, hematuria, asthenia, and fall in patients taking warfarin. This effect may be less pronounced in women due to the procoagulatory effects of estrogen signaling. Multiple possible DDIs were identified, including acetaminophen, ramipril, and furosemide.

An Inconspicuous Offender: Apixaban-Induced Anticoagulant-Related Nephropathy

Direct oral anticoagulants (DOACs) have shifted the landscape of anticoagulation over the past decade, becoming a frequently used pharmaceutical agent. The increased use of DOACs for long-term anticoagulation has led to a rise in reported anticoagulant-related adverse reactions, such as anticoagulant-related nephropathy (ARN). The occurrence of ARN is well reported with warfarin; however, there are few cases of ARN reported with DOAC use. We report the case of an elderly man with coronary artery disease and hypertension who was initiated on apixaban for atrial fibrillation three years prior to presentation but developed rapid renal decline over the six months prior to presentation. The estimated glomerular filtration rate (eGFR) had decreased precipitously from 48 mL/min/1.73 m2 to 19 mL/min/1.73 m2 with a concurrent drop in hemoglobin in the setting of persistent microscopic hematuria. A renal biopsy showed red blood cell casts consistent with glomerular hematuria, despite no crescents or signs of other forms of glomerulonephritis. The patient's renal function ceased to deteriorate and had a 35% recovery (serum creatinine 2.6 mg/dL, eGFR 25 mL/min/1.73 m2) after the discontinuation of apixaban and conversion to rivaroxaban without the use of corticosteroids. The patient reported at follow-up that he discontinued rivaroxaban four days after initiation on his own accord due to extrarenal bleeding. Our case highlights the importance of prompt recognition and treatment of the underreported but potentially significant incidence of ARN with apixaban in a patient with an otherwise unexplained kidney injury.

The impact of anticoagulation therapy on kidney function in patients with atrial fibrillation and chronic kidney disease

INTRODUCTION

Atrial fibrillation (AF) and chronic kidney disease (CKD) are closely related. These diseases share common risk factors and are associated with increased risk of thromboembolic events. Choosing the appropriate oral anticoagulant therapy (OAC) in patients with AF and CKD is challenging. Deterioration of renal function is common in patients with AF treated with OACs, although not all OACs affect the kidneys equally.

AREAS COVERED

In this review, we aim to summarize the current knowledge of the prevention of thromboembolic events in patients with AF and CKD, focusing on the impact of specific OAC agents on renal function.

EXPERT OPINION

Consideration of OAC use is mandatory in patients with AF and CKD who are at increased risk of stroke or systemic embolism. Available evidence suggests that the use of non-vitamin K antagonist oral anticoagulants (NOACs) is associated with slower deterioration of renal function in comparison to Vitamin K antagonists (VKAs). Hence, a NOAC should be used in preference to VKAs in all NOAC-eligible patients with AF and CKD. Regarding patients with end-stage renal dysfunction and those on dialysis or renal replacement therapy, the use of NOAC should be considered in line with locally relevant formal recommendations.

Nephrotoxins and acute kidney injury - The consensus of the Taiwan acute kidney injury Task Force

The Taiwan Acute Kidney Injury (AKI) Task Force conducted a review of data and developed a consensus regarding nephrotoxins and AKI. This consensus covers: (1) contrast-associated AKI; (2) drug-induced nephrotoxicity; (3) prevention of drug-associated AKI; (4) follow up after AKI; (5) re-initiation of medication after AKI. Strategies for the avoidance of contrast media related AKI, including peri-procedural hydration, sodium bicarbonate solutions, oral N-acetylcysteine, and iso-osmolar/low-osmolar non-ionic iodinated contrast media have been recommended, given the respective evidence levels. Regarding anticoagulants, both warfarin and new oral anticoagulants have potential nephrotoxicity, and dosage should be reduced if renal pathology exam proves renal injury. Recommended strategies to prevent drug related AKI have included assessment of 5R/(6R) reactions - risk, recognition, response, renal support, rehabilitation and (research), use of AKI alert system and computerized decision support. In terms of antibiotics-associated AKI, avoiding concomitant administration of vancomycin and piperacillin-tazobactam, monitoring vancomycin trough level, switching from vancomycin to teicoplanin in high-risk patients, and replacing conventional amphotericin B with lipid-based amphotericin B have been shown to reduce drug related AKI. With respect to non-steroidal anti-inflammatory drug associated AKI, it is recommended to use these drugs cautiously in the elderly and in patients receiving renin-angiotensin-aldosterone system inhibitors/diuretics triple combinations.

Investigation on Dabigatran Etexilate and Worsening of Renal Function in Patients with Atrial fibrillation: The IDEA Study

BACKGROUND AND OBJECTIVES

Warfarin-related nephropathy is an unexplained acute kidney injury, and may occur in patients with supratherapeutic INR, in the absence of overt bleeding. Similar findings have been observed in rats treated with dabigatran etexilate. We conducted a prospective study in dabigatran etexilate-treated patients to assess the incidence of dabigatran-related nephropathy and to investigate the possible correlation between dabigatran plasma concentration (DPC) and worsening renal function.

METHOD

One hundred and seven patients treated long term with dabigatran etexilate for non-valvular atrial fibrillation (NVAF) were followed up for 90 days. DPC, serum creatinine (SCr) and serum cystatin C were prospectively measured. Ninety five patients had complete follow-up data and were evaluable for primary endpoint.

RESULTS

Eleven patients had supratherapeutic DPC, defined as DPC higher than 200 ng/ml at study enrolment, but at the end of follow-up no patient showed a persistent increase in SCr. No patients experienced acute kidney injury.

CONCLUSIONS

Our study shows that no persistent renal detrimental effect is associated with dabigatran treatment. An increase in SCr during dabigatran treatment is reversible and it seems to be unrelated to dabigatran itself.

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.

Anticoagulant-Related Nephropathy

Anticoagulant-related nephropathy (ARN) is a newly recognized form of AKI in which overanticoagulation causes profuse glomerular hemorrhage, which manifests on renal biopsy as numerous renal tubules filled with red cells and red cell casts. The glomeruli show changes, but they are not sufficient to account for the glomerular hemorrhage. We were the first to study ARN, and since then, our work has been confirmed by numerous other investigators. Oral anticoagulants have been in widespread use since the 1950s; today, >2 million patients with atrial fibrillation take an oral anticoagulant. Despite this history of widespread and prolonged exposure to oral anticoagulants, ARN was discovered only recently, suggesting that the condition may be a rare occurrence. This review chronicles the discovery of ARN, its confirmation by others, and our animal model of ARN. We also provide new data on analysis of "renal events" described in the post hoc analyses of three pivotal anticoagulation trials and three retrospective analyses of large clinical databases. Taken together, these analyses suggest that ARN is not a rare occurrence in the anticoagulated patient with atrial fibrillation. However, much work needs to be done to understand the condition, particularly prospective studies, to avoid the biases inherent in post hoc and retrospective analyses. Finally, we provide recommendations regarding the diagnosis and management of ARN on the basis of the best information available.

Incidence of Visible Hematuria Among Antithrombotic Agents: A Systematic Review of Over 175,000 Patients

OBJECTIVE

To determine the probability of visible hematuria with antithrombotic agents and to evaluate association of urologic etiology in antithrombotic-related hematuria.

METHODS

Preferred Reporting Items in Systematic Reviews and Meta-Analyses guidelines were followed to conduct a systematic review using search engines PUBMED and SCOPUS with the terms "(hematuria) OR (haematuria) OR urinary bleeding)) AND ((anticoagulants) OR anticoagulation) OR noac) OR novel anticoagulants) OR antiplatelet) OR dabigatran) OR rivaroxaban) OR apixaban) OR warfarin) OR aspirin) OR heparin) OR dipyridamole)." Raw data were used to perform a pooled analysis. Chi-square and logistic regression analysis were used for statistical analyses.

RESULTS

Twenty-two studies describing 175,114 patients met inclusion criteria. Odds ratio of hematuria with warfarin to rivoraxaban was 33 and warfarin to dabigatran was 16. The odds ratio of hematuria for oral anticoagulant (26.7%) to prophylactic parenteral anticoagulant (1.1%) agents was 9.6. Antiplatelet agents are 76 times less likely to cause hematuria compared to anticoagulants. Odds of hematuria with aspirin were 6.7 times the odds with clopidogrel and 3.5 times the odds with ticagrelor. Dabigatran was 198 times more likely to cause major hematuria compared to warfarin, whereas clopidogrel is 1.2 times more likely to cause major hematuria compared to aspirin. Urologic pathology was identified in 44% (234/532) of cases, malignancy in 24%.

CONCLUSION

Warfarin use poses the greatest risk for hematuria but is unlikely to cause major hematuria, whereas novel antithrombotic agents are more commonly associated with major hematuria. This review further characterizes the risk profile of antithrombotic agents and associated hematuria to equip clinicians with knowledge to choose an appropriate antithrombotic agent in patients with high-risk hematuria.

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.

Acute kidney injury due to glomerular haematuria and obstructive erythrocyte casts associated with thrombocytopaenia and thin basement membrane disease: a case report

Background

Acute kidney injury due to glomerular bleeding has been described with IgA nephropathy and supratherapeutic warfarin anticoagulation. There is usually demonstrable tubular obstruction by erythrocyte casts associated with acute tubular injury. Although severe thrombocytopaenia increases the risk of bleeding, most cases of haematuria have been ascribed to non-glomerular or urological bleeding without a direct link to acute kidney injury. We describe a patient with acute kidney injury due to glomerular bleeding and tubular injury related to severe thrombocytopaenia, who was subsequently found to have thin basement membrane disease.

Case presentation

A 56 year old man presented with macroscopic haematuria, acute kidney injury and a platelet count of 35 × 10⁹/L, in the absence of anticoagulation. Urinalysis demonstrated an active urinary sediment. His kidney biopsy demonstrated extensive intraluminal erythrocyte casts associated with acute tubular injury, along with haemosiderin deposition suggestive of recurrent glomerular bleeding. There was no histological evidence of glomerular pathology but electron microscopy analysis demonstrated thin basement membrane disease and effacement of podocyte foot processes. During long term follow-up, thrombocytopaenia and intermittent haematuria persisted. At 9 months, the patient progressed to Stage 5 chronic kidney disease with the development of gross renal atrophy.

Conclusion

Recurrent macroscopic haematuria may be a risk factor for progressive renal injury in patients with thin basement membrane. The mechanism may be due to recurrent acute kidney injury from glomerular bleeding leading to repeated tubular damage. In the absence of anticoagulation, severe thrombocytopaenia may be a risk factor for heavy glomerular bleeding and acute kidney injury in these patients.

Macroscopic hematuria in patients on anticoagulation therapy

INTRODUCTION

Visible hematuria is not rare in patients on anticoagulant therapy. There is no consensus regarding the diagnostic approach for them; some authors suggest restricted volume of diagnostic procedures because of the low number of urological etiology found. Some antibiotics have been reported to potentiate the effect of oral anticoagulants.

MATERIAL AND METHODS

The study addresses the need for urological assessment of patients on anticoagulation therapy and the possible role of some drugs administrated simultaneously with an oral anticoagulant, for the onset of macroscopic hematuria. Patients hospitalized with hematuria, both with or without anticoagulation therapy, were investigated and followed up.

RESULTS

The onset of hematuria depends on the monitoring of oral anticoagulation. INR (International Normalized Ratio) value corresponds with the probability of non-urological etiology, where INR>4 carries relatively low risk for urological and malignant etiology. Some antibiotics may influence the anticoagulation effect, so INR value may be elevated and hematuria may occur.

CONCLUSIONS

Anticoagulation therapy should be administrated carefully and individually. The risk of urological etiology of hematuria is lower in patients on oral anticoagulants (especially when INR >4), however, it is not zero.

Anticoagulants and acute kidney injury: clinical and pathology considerations

We have recently identified a new clinical syndrome in patients receiving warfarin for anticoagulation therapy. This syndrome has been named warfarin-related nephropathy (WRN), and patients with chronic kidney disease (CKD) appear to be particularly susceptible. WRN is defined as an acute increase in international normalized ratio (INR) to >3.0, followed by evidence of acute kidney injury (AKI) within 1 week of the INR increase. AKI was defined as a sustained increase in serum creatinine of greater than or equal to 0.3 mg/dL. The AKI cannot be explained by any other factors, and the kidney biopsy demonstrates extensive glomerular hemorrhage with tubular obstruction by red blood cells (RBCs). Beyond AKI, WRN is a significant risk factor for mortality within the first 2 months of diagnosis and it accelerates the progression of CKD. We demonstrated that 5/6 nephrectomy in rats is a suitable experimental model to study WRN. Animals treated with warfarin showed an increase in serum creatinine and morphologic findings in the kidney similar to those in humans with WRN. Our recent evidence suggests that novel oral anticoagulants may induce AKI. Diagnosis of WRN may be challenging for a renal pathologist. A few cases with suspected WRN and pathologic considerations are described.

[Warfarin-related nephropathy: a case report]

INTRODUCTION

Warfarin-related nephropathy (WRN) is a newly recognized entity, which is characterized by the occlusion of renal tubules by red blood cells following glomerular hemorrhage in a patient overexposed to warfarin (international normalized ratio>3).

CASE REPORT

We report a 70-year-old man with no previous renal condition who developed WRN when his INR was>12. He did not fully recover his previous renal function.

CONCLUSION

The diagnosis of WRN should be considered whenever INR exceeds 3 in patients exposed to warfarin, particularly in the presence of hematuria. Vitamin K is the only therapeutic option.