Use of Warfarin in People with Low Glomerular Filtration Rate or on Dialysis

Clinical characteristics and treatment modalities in uremic and non uremic calciphylaxis - a dermatological single-center experience

Calciphylaxis (CP) is a serious, potentially life-threatening disease that presents with medial calcification of small-sized vessels and painful ischemic ulcerations. Although calciphylaxis is frequently seen in patients with end-stage kidney disease on dialysis (calcific uremic arteriolopathy, CUA), there are reported cases of nonuremic calciphylaxis (NUC), which often remain undiagnosed. We conducted a retrospective chart review at our dermatological hospital and evaluated data concerning the epidemiology, comorbidities, medication, laboratory abnormalities, and therapeutic approaches of 60 patients diagnosed with calciphylaxis between 01/2012 and 12/2022. We identified 21 patients diagnosed with NUC and 39 with kidney disease. The predilection sites of skin lesions were the lower legs in 88% (n = 53), followed by the thigh and gluteal regions in 7% (n = 4). Significant differences were identified in comorbidities, such as atrial fibrillation (p < 0.001) and hyperparathyroidism (p < 0.01) accounting for CUA patients. Medication with vitamin K antagonists (p < 0.001), phosphate binders (p < 0.001), and loop diuretics (p < 0.01) was found to be associated with the onset of calciphylaxis. Hyperphosphatemia (p < 0.001), increased parathyroid hormone (p < 0.01) and triglyceride levels (p < 0.01), hypoalbuminemia (p < 0.01) and decreased hemoglobin values (p < 0.001) in the CUA cohort were significantly different from those in the NUC group. All patients with CUA received systemic medication. In contrast, only 38% (n = 8) of patients with NUC received systemic treatment. Striking discrepancies in the treatment of both cohorts were detected. In particular, NUC remains a disease pattern that is still poorly understood and differs from CUA in several important parameters.

Oral anticoagulants, time in therapeutic range and renal function over time in real-life patients with atrial fibrillation and chronic kidney disease

Aims

To describe the use of warfarin and direct oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) and chronic kidney disease (CKD), to evaluate changes in renal function over time and predictors of rapid decline, and to describe time in therapeutic range (TTR) and predictors of poor TTR among patients on warfarin.

Methods and results

Using data from AuriculA, the Swedish oral anticoagulation registry, patients with AF on warfarin or DOAC were identified between 2013 and 2018 (N=6567). Estimated glomerular filtration rate (eGFR) was calculated and categorised into normal (≥90 mL/min/1.73 m²), mild CKD (60–89 mL/min/1.73 m²), moderate CKD (30–59 mL/min/1.73 m²), severe CKD (15–29 mL/min/1.73 m²) and end-stage CKD (<15 mL/min/1.73 m²)/dialysis. TTR was estimated using international normalised ratio (INR) measurements. Predictors of eGFR decline over time and of poor TTR were estimated using regression analysis. Between 2013 and 2018, use of DOAC increased from 9.2% to 89.3%, with a corresponding decline in warfarin. A similar trend was observed in patients with mild to moderate CKD, while DOAC over warfarin increased slower among patients with severe to end-stage CKD/dialysis. In patients treated with warfarin, the median TTR was 77.1%. Worse TTR was observed among patients with severe CKD (70.0%) and end-stage CKD/dialysis (67.5%). A gradual annual decline in eGFR was observed (−1.1 mL/min/1.73 m²), with a more rapid decline among patients with older age, female sex, diabetes mellitus and/or heart failure.

Conclusion

In patients with AF, use of DOAC has steadily increased across different CKD stages, but not in patients with severe to end-stage CKD/dialysis despite these patients having poor INR control. Patients with AF have a gradual decline in renal function, with a more rapid decline among a subgroup of patients.

Influence of Renal Impairment and Genetic Subtypes on Warfarin Control in Japanese Patients

The genotypes of vitamin K epoxide reductase complex 1 (VKORC1) and cytochrome P450 2C9 (CYP2C9) can influence therapeutic warfarin doses. Conversely, nongenetic factors, especially renal function, are associated with warfarin maintenance doses; however, the optimal algorithm for considering genes and renal dysfunction has not been established. This single-center prospective cohort study aimed to evaluate the factors affecting warfarin maintenance doses and develop pharmacogenetics-guided algorithms, including the factors of renal impairment and others. To commence, 176 outpatients who were prescribed warfarin for thromboembolic stroke prophylaxis in the stroke center, were enrolled. Patient characteristics, blood test results, dietary vitamin K intake, and CYP2C9 and VKORC1 (-1639G>A) genotypes were recorded. CYP2C9 and VKORC1 (-1639G>A) genotyping revealed that 80% of the patients had CYP2C9 *1/*1 and VKORC1 mutant AA genotypes. Multiple linear regression analysis demonstrated that the optimal pharmacogenetics-based model comprised age, body surface area, estimated glomerular filtration rate (eGFR), genotypes, vitamin K intake, aspartate aminotransferase levels, and alcohol intake. eGFR exercised a significant impact on the maintenance doses, as an increase in eGFR of 10 mL/min/1.73 m² escalated the warfarin maintenance dose by 0.6 mg. Reduced eGFR was related to lower warfarin maintenance doses, independent of VKORC1 and CYP2C9 genotypes in Japanese patients.

Effects of warfarin on biological processes other than haemostasis: A review

Warfarin is the world's most widely used anticoagulant drug. Its anticoagulant activity is based on the inhibition of the vitamin K-dependent (VKD) step in the complete synthesis of a number of blood coagulation factors that are required for normal blood coagulation. Warfarin also affects synthesis of VKD proteins not related to haemostasis including those involved in bone growth and vascular calcification. Antithrombotic activity of warfarin is considered responsible for some aspects of its anti-tumour activity of warfarin. Some aspects of activities against tumours seem not to be related to haemostasis and included effects of warfarin on non-haemostatic VKD proteins as well as those not related to VKD proteins. Inflammatory/immunomodulatory effects of warfarin indicate much broader potential of action of this drug both in physiological and pathological processes. This review provides an overview of the published data dealing with the effects of warfarin on biological processes other than haemostasis.

Warfarin Use in Hemodialysis Patients With Atrial Fibrillation: A Systematic Review of Stroke and Bleeding Outcomes

Background:

Given the lack of clear indications for the use of warfarin in the treatment of atrial fibrillation (AF) in patients on hemodialysis and the potential risks that accompany warfarin use in these patients, we systematically reviewed stroke and bleeding outcomes in hemodialysis patients treated with warfarin for AF.

Objective:

To systematically review the stroke and bleeding outcomes associated with warfarin use in the hemodialysis population to treat AF.

Design:

Systematic review.

Setting:

All adult hemodialysis patients.

Patients:

Patients on hemodialysis receiving warfarin for the management of AF.

Measurements:

Any type of stroke and/or bleeding outcomes.

Methods:

MEDLINE(R) In-Process & Other Non-Indexed Citations and MEDLINE(R) via OVID (1946 to January 11, 2017), and EMBASE via OVID (1974 to January 11, 2017) were searched for relevant literature. Inclusion criteria were randomized controlled trials, observational studies, and case series in English that examined stroke and bleeding outcomes in adult population of patients (over 18 years old) who are on hemodialysis and taking warfarin for AF. Studies with less than 10 subjects, case reports, review articles, and editorials were excluded. Quality of selected articles was assessed using Newcastle-Ottawa Scale (NOS).

Results:

Of the 2340 titles and abstracts screened, 7 met the inclusion criteria. Two studies showed an association between warfarin use and an increased risk of stroke (Hazard Ratio: 1.93-3.36) but no association with an increased risk of bleed (HR: 0.85-1.04), while 4 studies showed no association between warfarin and stroke outcomes (HR: 0.12-1.17) but identified an association between warfarin and increased bleeding outcome (HR: 1.41-3.96). And 1 study reported neither beneficial nor harmful effects associated with warfarin use.

Limitations:

The major limitation to this review is that the 7 included studies were observational cohort studies, and thus the outcome measures were not specified and predetermined in a research protocol.

Conclusion:

Our systematic review demonstrated that for patients with AF who are on hemodialysis, warfarin was not associated with reduced outcomes of stroke but was rather associated with increased bleeding events.

Warfarin utilisation and anticoagulation control in patients with atrial fibrillation and chronic kidney disease

OBJECTIVE

To evaluate warfarin prescription, quality of international normalised ratio (INR) monitoring and of INR control in patients with atrial fibrillation (AF) and chronic kidney disease (CKD).

METHODS

We performed a retrospective cohort study of patients with newly diagnosed AF in the Veterans Administration (VA) healthcare system. We evaluated anticoagulation prescription, INR monitoring intensity and time in and outside INR therapeutic range (TTR) stratified by CKD.

RESULTS

Of 123 188 patients with newly diagnosed AF, use of warfarin decreased with increasing severity of CKD (57.2%-46.4%), although it was higher among patients on dialysis (62.3%). Although INR monitoring intensity was similar across CKD strata, the proportion with TTR≥60% decreased with CKD severity, with only 21% of patients on dialysis achieving TTR≥60%. After multivariate adjustment, the magnitude of TTR reduction increased with CKD severity. Patients on dialysis had the highest time markedly out of range with INR <1.5 or >3.5 (30%); 12% of INR time was >3.5, and low TTR persisted for up to 3 years.

CONCLUSIONS

There is a wide variation in anticoagulation prescription based on CKD severity. Patients with moderate-to-severe CKD, including dialysis, have substantially reduced TTR, despite comparable INR monitoring intensity. These findings have implications for more intensive warfarin management strategies in CKD or alternative therapies such as direct oral anticoagulants.

Use of Oral Anticoagulation in the Management of Atrial Fibrillation in Patients with ESRD: Con

Among patients with atrial fibrillation, prophylaxis for stroke prevention with the use of anticoagulation is well established in the general population. A number of randomized controlled trials and evidence-based risk prediction tools clearly delineate the benefit and risks of therapy. Despite the high incidence of atrial fibrillation in the late stage CKD and ESRD populations, little high quality evidence exists in these populations. Is it appropriate then to extrapolate findings from the general population to those with CKD/ESRD? In our view, too much uncertainty exists regarding proof of efficacy with clear signals of harm. Routine anticoagulation for stroke prevention in atrial fibrillation is not recommended for the majority of CKD and ESRD patients.

Use of direct oral anticoagulants in patients with nonvalvular atrial fibrillation according to clinical profile

The majority of patients with atrial fibrillation should receive oral anticoagulation to reduce the risk of stroke. The limitations of vitamin K antagonists have led to an underuse of anticoagulants in clinical practice which has been associated with a higher risk of stroke, hospitalizations and healthcare costs. Direct oral anticoagulants (DOACs) overcome some of the limitations of vitamin K antagonists and may therefore increase the use of oral anticoagulants in clinical practice. Since no head-to-head trials have been performed, only indirect comparisons can be made among them. In this review, the results of the Phase III randomized controlled trials with DOACs were analyzed, trying to determine whether one or more DOACs could be especially recommended according to different clinical conditions.

Atrial fibrillation and chronic kidney disease: focus on rivaroxaban

Renal insufficiency increases the risk of stroke and bleeding in atrial fibrillation patients. Although vitamin K antagonists reduce the risk of stroke in patients with moderate renal dysfunction, this observation is less clear in patients with renal impairment. Moreover, the risk of bleeding with vitamin K antagonists increases as renal function worsens. Maintaining international normalized ratio values within therapeutic targets is more difficult in patients with renal dysfunction, and those agents may cause warfarin-related nephropathy and vascular calcification. Rivaroxaban is the only nonvitamin K oral anticoagulant with a dose specifically tested in patients with moderate renal insufficiency. Rivaroxaban is effective for the prevention of stroke in atrial fibrillation patients with moderate renal dysfunction, with a lower risk of intracranial and fatal bleeding.

Anticoagulant and antiplatelet therapy in patients with chronic kidney disease: risks versus benefits review

PURPOSE OF REVIEW

Atrial fibrillation and cardiovascular death are increased in end-stage renal disease (ESRD) patients compared to the general population. The effect of anticoagulant and antiplatelet medications for these indications in ESRD is unclear. However, both classes of medications have been used for the preservation of vascular access. This review explores the risks and benefits of anticoagulant and antiplatelet medications in ESRD.

RECENT FINDINGS

ESRD patients with atrial fibrillation have a two and three-fold greater risk of death and stroke, respectively, than ESRD patients without atrial fibrillation. Warfarin does not appear to decrease this risk, and increases the risk of bleeding and vascular calcification. Warfarin also does not appear to be effective for vascular access preservation. In a few large observational studies, antiplatelet agents did not decrease the risk of cardiovascular death, but confounding by indication is likely. Antiplatelet agents do appear to prolong unassisted arteriovenous graft patency, but the effect is modest.

SUMMARY

The role of anticoagulant and antiplatelet agents for atrial fibrillation and cardiovascular disease in ESRD remains unclear. Well designed randomized controlled trials to determine the role of anticoagulation in ESRD patients with atrial fibrillation, and anticoagulant and antiplatelet medications in the preservation of central venous catheter function are required.

[Thrice-weekly warfarin administration: results in 12 hemodialysis patients]

We report our experience of thrice-weekly warfarin administration, at the end of the dialysis session, in 12 patients (average age: 79 ± 5 years). In 10 cases, indication for anticoagulation therapy was atrial fibrillation, in one case a mechanical heart valve, in another case axillo femoral bypass. The International Normalized Ratio (INR) therapeutic goal was between 2 and 3, except for the patient with a mechanical aortic heart valve, whose goal was between 2.5 and 3.5. The INR was determined during the first dialysis session of the week. The thrice-weekly warfarin dose was based on this result. INR stability was assessed for each patient over an uninterrupted period of treatment of at least 6 months. The average duration of warfarin treatment was 20 ± 5 months. One in two patients had hypertensive nephropathy. The average Charlson co-morbidity score was 9 ± 1. Four patients were also taking aspirin or clopidogrel. The 10 patients with atrial fibrillation had an average CHA(2)DS(2)-VASc score of 4.4 ± 0.8. The average haemorrage risk HAS-BLED score was 3.3 ± 0.6. The average weekly warfarin dose was 23 ± 5 mg. No thrombotic events were observed. The side effects of warfarin were minor in most cases: (1) INR more than 6 in two cases without associated bleeding; (2) minor bleeding (nose, bladder) in three cases. One case of skin necrosis was observed. No cases of major bleeding (requiring blood transfusion) were observed. Only one patient was admitted into hospital as a result of warfarin treatment (the case of skin necrosis). Five hundred and forty-seven INR results were analyzed: 65% of these results were within the therapeutic goal, only 3% were either beneath 1.5 or over 4. To conclude, warfarin administration at the end of the dialysis session is efficient and associated with remarkable INR stability in the goal. It enables precise dose adaptation and optimum therapeutic observance, which in turn reduces the risk of bleeding.

Statin use and calcific uremic arteriolopathy: a matched case-control study

BACKGROUND

Calcific uremic arteriolopathy (CUA), also known as calciphylaxis, is characterized by vascular calcification, thrombosis and intense inflammation. Prior research has shown that statins have anticalcification, antithrombotic and antiinflammatory properties; however, the association between statin use and CUA has not been investigated.

METHODS

This matched case-control study included 62 adult maintenance hemodialysis (HD) patients with biopsy-confirmed CUA diagnosed between the years 2002 and 2011 (cases). All cases were hospitalized at the time of diagnosis. Controls (n = 124) were hospitalized maintenance HD patients without CUA (matched to cases by gender and timing of hospitalization). Univariate and multivariable logistic regression models were applied to compute odds ratio (OR) and 95% confidence intervals (CI) for CUA in statin users, and also to examine previously described associations.

RESULTS

The mean age of cases was 58 years. Most were females (68%), and of white race (64%). Statin use was more common in controls than in cases (39 vs. 19%, p < 0.01). Statin use was associated with lower odds of CUA in unadjusted (OR 0.38, 95% CI 0.18-0.79) and adjusted (OR 0.20, 95% CI 0.05-0.88) analyses. Hypercalcemia (OR 2.25, 95% CI 1.14-4.43), hypoalbuminemia (OR 5.73, 95% CI 2.79-11.77), calcitriol use (OR 5.69, 95% CI 1.02-31.77) and warfarin use (OR 4.30, 95% CI 1.57-11.74) were positively associated with CUA in adjusted analyses whereas paricalcitol and doxercalciferol were not (OR 1.33, 95% CI 0.54-3.27).

CONCLUSION

Statin use may be negatively associated with odds of CUA. Further large prospective studies with attention to potential confounders are needed to confirm these findings.

Vascular calcification: the price to pay for anticoagulation therapy with vitamin K-antagonists

Vitamin K-antagonists (VKA) are the most widely used anti-thrombotic drugs with substantial efficacy in reducing risk of arterial and venous thrombosis. Several lines of evidence indicate, however, that VKA inhibit not only post-translational activation of vitamin K-dependent coagulation factors but also synthesis of functional extra-hepatic vitamin K-dependent proteins thereby eliciting undesired side-effects. Vascular calcification is one of the recently revealed side-effects of VKA. Vascular calcification is an actively regulated process involving vascular cells and a number of vitamin K-dependent proteins. Mechanistic understanding of vascular calcification is essential to improve VKA-based treatments of both thrombotic disorders and atherosclerosis. This review addresses vitamin K-cycle and vitamin K-dependent processes of vascular calcification that are affected by VKA. We conclude that there is a growing need for better understanding of the effects of anticoagulants on vascular calcification and atherosclerosis.

Central venous catheters: legal issues

In dialysis patients, both central venous catheter (CVC) insertion and CVC use during the dialysis procedure pose important legal issues, because of potentially severe, even fatal, complications. The first issue is the decision of the kind of vascular access that should be proposed to patients: an arteriovenous (AV) fistula, a graft, or a CVC. The second issue, when choosing the CVC option, is the choice of CVC: nontunneled versus tunneled. Leaving a temporary nontunneled CVC for a prolonged time increases the risk of complications and could raise a liability issue. Even when choosing a long-term tunneled CVC, nephrologists should systematically explain its potential harms, presenting them as "unsafe for long-term use" unless there is a clear contraindication to an AV native or prosthetic access. Another critical issue is the preparation of a complete, informative, and easy-to-understand consent form. The CVC insertion procedure has many aspects of legal interest, including the choice of CVC, the use of ECG monitoring, the use of ultrasound guidance for cannulation, and the use of fluoroscopy for checking the position of the metal guidewire during the procedure as well as the CVC tip before the end of the procedure. Use of insertion devices and techniques that can prevent complications should obviously be encouraged. Complications of CVC use are mainly thrombosis and infection. These are theoretically expected as pure complications (and not as malpractice effects), but legal issues might relate to inappropriate catheter care (in both the inpatient and outpatient settings) rather than to the event per se. Thus, in the individual case it is indeed very difficult to establish malpractice and liability with a catheter-related infection or thrombosis. In conclusion, we cannot avoid complications completely when using CVCs, but reducing them to a minimum and adopting safe approaches to their insertion and use will reduce legal liability.

Warfarin in haemodialysis patients with atrial fibrillation: what benefit?

Warfarin is commonly used to prevent stroke in patients with atrial fibrillation; however, patients on haemodialysis may not derive the same benefit from warfarin as the general population. There are no randomized controlled studies in dialysis patients which demonstrate the efficacy of warfarin in preventing stroke. In fact, warfarin places the dialysis patient at increased risk for haemorrhagic stroke and possibly ischaemic stroke. Additionally, warfarin increases the risk of major bleeding and has been associated with vascular calcification. Routine use of warfarin in dialysis for stroke prevention should be discouraged, and therapy should only be reserved for dialysis patients at high risk for thrombo-embolic stroke and carefully monitored if implemented.