Use of Direct Anticoagulants in Kidney Transplant Recipients: Review of the Current Evidence and Emerging Perspectives

Thromboembolic events and atrial fibrillation are common among kidney transplant recipients (KTRs), and these conditions typically require anticoagulation. Traditionally, vitamin K antagonists were used for management, but the use of direct oral anticoagulants (DOACs) has increased in KTRs. In the general population, DOACs are recommended over warfarin, but the applicability of these recommendations to KTRs is unclear because of risk-benefit concerns. There is some hesitancy to use DOACs in KTRs because of their dependence on renal clearance for elimination, potential drug-drug interactions, and limited data. To date, studies of DOACs in KTRs have demonstrated that they are efficient in thromboembolic events, major bleeding is rare, and drug-drug interactions appear rare. However, no guidance yet exists about the use of DOACs, reversal of DOAC action, and the pre- and post-kidney transplant management of DOACs in KTRs, and the evidence base is scarce. Thus, decisions on DOAC use in KTRs are based on expert opinion and the resources and experiences of individual transplant centers. This review summarizes 10 published studies on the use of DOACs in 741 KTRs, evaluating the side effects, efficacy, drug-drug interactions, and perioperative management compared with those of 1320 KTRs using vitamin K antagonists. Although current data are limited, DOACs appear to be relatively safe and effective in KTRs, with some studies suggesting lower bleeding rates and better kidney function than with vitamin K antagonists. However, more research with larger patient groups is needed to draw definitive conclusions.

Related factors and safety of reaching the therapeutic target of warfarin after heart valve surgery in hospitalized patients: A retrospective cohort study

Warfarin is a commonly employed anticoagulant drug aimed at rapidly reaching the optimal international normalized ratio (INR), potentially reducing the hospitalization time in clinical settings. However, limited research has been conducted on the influencing factors and the safety implications of promptly reaching the target INR range in patients with valvular heart disease who have undergone valve replacement or repair. The present study aimed to assess the factors related to the safety considerations of rapidly reaching the target INR range in patients treated with warfarin. A retrospective cohort investigation was performed on hospitalized patients treated with warfarin between July 2022 and June 2023. Patient data were gathered from patient documentation. A total of 175 patients were included in the current study. The mean time to reach an effective INR threshold was 9.8 days (median, 3-28 days). Age >65 years, body mass index <24 kg/m2, no smoking history and warfarin starting dose ≥3 mg/day were separate factors linked to rapidly reaching the effective INR threshold for warfarin management. The occurrence of INR levels ≥4 was significantly elevated among patients who reached the effective INR threshold more rapidly, while bleeding incidents were not significantly different. Inpatients aged >65 years, those with a body mass index <24 kg/m², no smoking history or prescribed a starting warfarin dosage ≥3 mg/day had a higher likelihood of rapidly reaching the effective INR threshold with warfarin. To enhance safety for these patients, enhanced INR tracking and suitable warfarin dosage adjustments are suggested following the initiation of oral warfarin therapy.

Direct Oral Anticoagulants in Patients With ESRD and Kidney Transplantation

Direct oral anticoagulant (DOAC) use has significantly increased because major medical organizations endorse their role for conditions in which anticoagulation is indicated. Owing to important pharmacokinetic properties, the use of apixaban and rivaroxaban requires careful consideration in at-risk populations such as those with kidney disease. Both apixaban and rivaroxaban undergo some degree of renal elimination, and thus total drug exposure is increased in patients with renal insufficiency and/or those undergoing renal replacement therapy (RRT). The available clinical trial and real-world data in this population suggests that apixaban is likely at least comparably effective as warfarin at preventing thromboembolic events and is likely safer when evaluating bleeding risk. Rivaroxaban data is more limited, and the reported results are more discordant. Both apixaban and rivaroxaban have been used successfully in patients with end-stage renal disease (ESRD) undergoing kidney transplant listing as well as in the posttransplant setting. Prospective clinical trials evaluating the safety and efficacy of apixaban and rivaroxaban in various conditions where anticoagulation is indicated should include patients with ESRD and kidney transplant recipients to help further define the role that these important novel agents should play in these complex patient populations.

When anticoagulation management in atrial fibrillation becomes difficult: Focus on chronic kidney disease, coagulation disorders, and cancer

Anticoagulation therapy (AT) is fundamental in atrial fibrillation (AF) treatment but poses challenges in implementation, especially in AF populations with elevated thromboembolic and bleeding risks. Current guidelines emphasize the need to estimate and balance thrombosis and bleeding risks for all potential candidates of antithrombotic therapy. However, administering oral AT raises concerns in specific populations, such as those with chronic kidney disease (CKD), coagulation disorders, and cancer due to lack of robust data. These groups, excluded from large direct oral anticoagulants trials, rely on observational studies, prompting physicians to adopt individualized management strategies based on case-specific evaluations. The scarcity of evidence and specific guidelines underline the need for a tailored approach, emphasizing regular reassessment of risk factors and anticoagulation drug doses. This narrative review aims to summarize evidence and recommendations for challenging AF clinical scenarios, particularly in the long-term management of AT for patients with CKD, coagulation disorders, and cancer.

Immunosuppressive therapy and oral anticoagulation in kidney transplant recipients: Direct oral anticoagulants versus vitamin-k antagonists

BACKGROUND

direct oral anticoagulants (DOACs) are an alternative to conventional antagonist of vitamin-K (AVK). However, immune suppressive drugs (ISDs) may interfere with DOACs pharmacokinetic.

AIM OF THIS STUDY

evaluate safety and efficacy profile of DOACs compared to AVK in kidney transplant recipients (KTRs) treated with ISDs.

METHODS

a multi-center study from 4 Italian University hospitals enrolling consecutive KTRs on DOACs or AVK was carried out. Sixty-six patients on DOACs were compared with fifty patients on AVK with similar clinical features. Serial evaluation of renal function and serum levels of ISDs during 18 months follow-up (FU) was performed.

RESULTS

Mean age of DOACs patients was 67±9 and mean eGFR was 58,3± 30,4mL/min/1.73m2. ISDs included tacrolimus (n=47, 71%), cyclosporin (n=13, 20%), everolimus (n=10, 7%) and sirolimus (n=4, 6%). After 14 days of DOACs therapy initiation there was a slight increase of serum levels of tacrolimus (+0.19±0.67 p=0.80) and cyclosporine (+0.12±0.25 p=0.94) not statistically significant. Levels of Tacrolimus and cyclosporin were stable at serial evaluation during 18-months follow-up. There were no thromboembolic events among patients treated with DOACs or AVK and no differences in term of major bleeding (6% vs 4% p=0.69), at long-term follow-up. There was no difference in term of eGFR decline from start therapy to 18 months FU between DOACs vs AVK therapy (-3.9±1 vs -3.8±2 p=0.82).

CONCLUSION

DOACs have similar safety and efficacy than AVK among KTRs treated with ISDs. However, careful evaluation of potential drug interaction and ISDs serum levels is needed.

Descriptive analysis evaluating the use of direct oral anticoagulation therapy in heart and lung transplant recipients

BACKGROUND

Direct oral anticoagulants (DOACs) are widely utilized following cardiothoracic transplantation with limited guidance regarding drug-drug interactions (DDIs), periprocedural management, and DOAC-specific monitoring.

METHODS

We performed a single-center, retrospective, descriptive analysis of adult cardiothoracic transplant recipients initiated on DOAC therapy between May 2016 and July 2021. The primary endpoint for this analysis was the percentage of patients dosed per package labeling. Secondary endpoints included DOAC prescribing in the context of DDIs, renal dysfunction, and periprocedural management, as well as thromboembolism and major bleeding at 12 months.

RESULTS

A total of 125 patients were included in this analysis with a median age of 62 years. At initiation, 63.2% of patients were dosed according to package labeling. The most common reason for non-labeled dosing was concomitant azole antifungal therapy. DOAC therapy was held for 82 procedures with no reported thrombotic events and one major bleed in the setting of AKI. Hemodialysis-dependence was associated with a reduced risk of thrombosis (0 vs. 10 events per 100 PY, p = .002) and an increased risk of major bleeding (23 vs. 8 events per 100 PY, p = .006). Additionally, DOAC-specific anti-xa guided dosing was associated with a reduced risk of major bleeding (0 vs. 13 events per 100 PY, p < .001).

CONCLUSION

Our findings show that deviation from package labeling is common following cardiothoracic transplantation and its association with clinical outcomes warrants further study.

Safety and mortality outcomes for direct oral anticoagulants in renal transplant recipients

PURPOSE

Direct oral anticoagulants (DOACs) are increasingly used in renal transplant recipients (RTR), but relatively understudied in this population. We assess the safety of post-transplant anticoagulation with DOACs compared to warfarin.

METHODS

We conducted a retrospective study of RTRs at the Mayo Clinic sites (2011-present) that were anticoagulated for greater than 3 months excluding the 1st month post-transplant. The main safety outcomes were bleeding and all-cause mortality. Concomitant antiplatelet and interacting drugs were noted. DOAC dose adjustment was assessed according to common US prescribing practices, guidelines, and/or FDA labeling.

RESULTS

The median follow-up was longer for RTRs on warfarin (1098 days [IQR 521, 1517]) than DOACs (449 days [IQR 338, 942]). Largely, there were no differences in baseline characteristics and comorbidities between RTRs on DOACs (n = 208; apixaban 91.3%, rivaroxaban 8.7%) versus warfarin (n = 320). There was no difference in post-transplant use of antiplatelets, immunosuppressants, most antifungals assessed, or amiodarone. There was no significant difference in incident major bleeding (8.4 vs. 5.3%, p = 0.89), GI bleeding (4.4% vs. 1.9%, p = 0.98), or intra-cranial hemorrhage (1.9% vs. 1.4%, p = 0.85) between warfarin and DOAC. There was no significant difference in mortality in the warfarin group compared to DOACs when adjusted for follow-up time (22.2% vs. 10.1%, p = 0.21). Rates of post-transplant venous thromboembolism, atrial fibrillation or stroke were similar between the two groups. 32% (n = 67) of patients on DOACs were dose reduced, where 51% of those reductions were warranted. 7% of patients that were not dose reduced should have been.

CONCLUSIONS

DOACs did not have inferior bleeding or mortality outcomes compared to warfarin in RTRs. There was greater use of warfarin compared to DOACs and a high rate of improper DOAC dose reduction.

Safety of Non-Vitamin K Antagonist Oral Anticoagulant Treatment in Patients with Chronic Kidney Disease and Kidney Transplant Recipients

The use of novel oral anticoagulants in patients with impaired renal function or undergoing immunosuppressive therapy is limited due to the risk of drug-to-drug interactions and anticoagulation-related adverse events. This article aims to assess the current data on the safety of direct-acting oral anticoagulant-based therapy in the population of kidney transplant recipients and patients with impaired renal function. The most important factors affecting the safety of treatment are the incidence of bleeding events, thromboembolic events, deaths and drug-to-drug interactions. The available data were compared to the findings on warfarin-based anticoagulation. Findings on the use of novel oral anticoagulants in kidney transplant recipients are limited yet promising in terms of safety and efficacy of use. However, current recommendations state that the co-administration of non-vitamin K antagonist oral anticoagulants with several immunosuppressive agents is contraindicated.

A Review of Direct-acting Oral Anticoagulants and Their Use in Solid Organ Transplantation

Direct-acting oral anticoagulant (DOAC) use has increased dramatically since their introduction because of the growing evidence of proven efficacy and enhanced safety compared with warfarin and the low-molecular-weight heparins in the general population. Unfortunately, there is a dearth of quality data regarding the safety and efficacy of the DOACs in patients awaiting organ transplant and those who received a solid organ transplant. This review aims to evaluate the available literature and considerations regarding anticoagulation use in transplant recipients, focusing on preoperative, perioperative, and postoperative DOAC use.

New Approaches to Cardiovascular Disease and Its Management in Kidney Transplant Recipients

Cardiovascular events, including ischemic heart disease, heart failure, and arrhythmia, are common complications after kidney transplantation and continue to be leading causes of graft loss. Kidney transplant recipients have both traditional and transplant-specific risk factors for cardiovascular disease. In the general population, modification of cardiovascular risk factors is the best strategy to reduce cardiovascular events; however, studies evaluating the impact of risk modification strategies on cardiovascular outcomes among kidney transplant recipients are limited. Furthermore, there is only minimal guidance on appropriate cardiovascular screening and monitoring in this unique patient population. This review focuses on the limited scientific evidence that addresses cardiovascular events in kidney transplant recipients. Additionally, we focus on clinical management of specific cardiovascular entities that are more prevalent among kidney transplant recipients (ie, pulmonary hypertension, valvular diseases, diastolic dysfunction) and the use of newer evolving drug classes for treatment of heart failure within this cohort of patients. We note that there are no consensus documents describing optimal diagnostic, monitoring, or management strategies to reduce cardiovascular events after kidney transplantation; however, we outline quality initiatives and research recommendations for the assessment and management of cardiovascular-specific risk factors that could improve outcomes.

Drug-Drug Interactions of Direct Oral Anticoagulants (DOACs): From Pharmacological to Clinical Practice

The direct oral anticoagulants (DOACs), dabigatran, rivaroxaban, apixaban, and edoxaban, are becoming the most commonly prescribed drugs for preventing ischemic stroke in patients with non-valvular atrial fibrillation (NVAF) and for the treatment and prevention of venous thromboembolism (VTE). Rivaroxaban was also recently approved for the treatment of patients with a recent acute coronary syndrome (ACS). Their use demonstrated to have a favorable risk-benefit profile, with significant reductions in stroke, intracranial hemorrhage, and mortality compared to warfarin, but with increased gastrointestinal bleeding. Nevertheless, their safety profile is compromised in multimorbidity patients requiring contemporary administration of several drugs. Comorbidity and polypharmacy have a high prevalence in elderly patients, who are also more susceptible to bleeding events. The combination of multiple treatments can cause relevant drug–drug interactions (DDIs) by affecting the exposure or the pharmacological activities of DOACs. Although important differences of the pharmacokinetic (PK) properties can be observed between DOACs, all of them are substrate of P-glycoprotein (P-gp) and thus may interact with strong inducers or inhibitors of this drug transporter. On the contrary, rivaroxaban and, to a lower extent, apixaban, are also susceptible to drugs altering the cytochrome P450 isoenzyme (CYP) activities. In the present review, we summarize the potential DDI of DOACs with several classes of drugs that have been reported or have characteristics that may predict clinically significant DDIs when administered together with DOACs. Possible strategies, including dosage reduction, avoiding concomitant administration, or different time of treatment, will be also discussed to reduce the incidence of DDI with DOACs. Considering the available data from specific clinical trials or registries analysis, the use of DOACs is associated with fewer clinically relevant DDIs than warfarin, and their use represents an acceptable clinical choice. Nevertheless, DDIs can be significant in certain patient conditions so a careful evaluation should be made before prescribing a specific DOAC.

Pharmacokinetics of Apixaban and Tacrolimus or Cyclosporine in Kidney and Lung Transplant Recipients

Apixaban is frequently used off‐label in transplant recipients. However, a potential drug interaction exists with the calcineurin inhibitors. We conducted an open‐label drug–drug interaction study to determine the pharmacokinetics of apixaban in lung and kidney transplant recipients who were taking a calcineurin inhibitor. A single dose of apixaban 10 mg was administered orally to kidney and lung transplant recipients maintained on either tacrolimus or cyclosporine, and pharmacokinetic parameters were compared to a reference cohort of 12 healthy subjects who used the same apixaban dose and pharmacokinetic blood sampling. Fourteen participants were enrolled (n = 6 kidney, n = 8 lung), with 10 maintained on tacrolimus and four on cyclosporine. Data from 13 participants was usable. Participants were taking triple therapy immunosuppression and had a mean (SD) of 12 (3) medications. Participants receiving tacrolimus and cyclosporine had area under the plasma concentration–time curve from time zero to infinity (AUC_0‐inf) geometric least square means (90% confidence interval [CI]) of 4312 (95% CI 3682, 5049) and 5388 (95% CI 3277, 8858), respectively. Compared to healthy subjects, the associated geometric mean ratios (GMRs) for apixaban maximum plasma concentration (C_max), AUC from time zero to the last quantifiable concentration (AUC_0‐tlast) and AUC_0‐inf were 197% (95% CI 153, 295), 244% (95% CI 184, 323), and 224% (95% CI 170, 295) for transplant recipients on tacrolimus. The GMR (90% CI) C_max, AUC_0‐tlast, and AUC_0‐inf of apixaban for patients on cyclosporine were 256% (95% CI 184, 358), 287% (95% CI 198, 415), and 280% (95% CI 195, 401). Kidney and lung transplant recipients receiving tacrolimus had higher apixaban exposure. A similar trend was noted for patients receiving cyclosporine, but additional patients are needed to confirm this interaction. Future studies are needed before apixaban can be safely recommended in this population, and the impact of dose staggering should be investigated. This study highlights the importance of pharmacokinetic studies in actual patient populations.

How to Deal With Kidney Retransplantation-Second, Third, Fourth, and Beyond

Kidney transplantation is the best health option for patients with end-stage kidney disease. Ideally, a kidney transplant would last for the lifetime of each recipient. However, depending on the age of the recipient and details of the kidney transplant, there may be a need for a second, third, fourth, or even more kidney transplants. In this overview, the outcome of multiple kidney transplants for an individual is presented. Key issues include surgical approach and immunologic concerns. Included in the surgical approach is an analysis of transplant nephrectomy, with indications, timing, and immunologic impact. Allograft thrombosis, whether related to donor or recipient factors merits investigation to prevent it from happening again. Other posttransplant events such as rejection, viral illness (polyomavirus hominis type I), recurrent disease (focal segmental glomerulosclerosis), and posttransplant lymphoproliferative disease may lead to the need for retransplantation. The pediatric recipient is especially likely to need a subsequent kidney transplant. Finally, noncompliance/nonadherence can affect both adults and children. Innovative approaches may reduce the need for retransplantation in the future.

The Use of Non-Vitamin K Antagonist Oral Anticoagulants in Post-Kidney Transplantation, Single-Center Experience

BACKGROUND

Novel oral anticoagulants (NOACs) are widely used alternatives to warfarin, because they do not require routine monitoring and have better safety profile. There is limited experience for NOACs in organ transplant recipients.

METHODS

This study assessed NOAC safety and efficacy among renal transplant recipients in a single center. A retrospective matched cohort study was conducted among the adult renal transplant recipients concomitantly administered calcineurin inhibitors (tacrolimus or cyclosporin) and NOACs between November 2015 and December 2019.

RESULTS

The study included 16 patients divided into 2 equal groups on NOACs and warfarin. Male patients constitute 50% and 75% of the NOAC group and warfarin group, respectively, and 75% and 87.5% of cases are post living donor transplants in the NOAC group and warfarin group, respectively. In the NOAC group, the most common indication for anticoagulation was atrial fibrillation (62.5%), followed by deep vein thrombosis (37.5%), whereas in the warfarin group, the most common indication was atrial fibrillation (50%), followed by valve replacement (25%). In the NOAC group, 6 patients (75%) received rivaroxaban, 1 patient (12.5%) received dabigatran, and 1 patient (12.5%) received apixaban; 68.75% of patients were on a tacrolimus-based regimen. There were no thromboembolic events, rejection episodes, bleeding, or admissions due to NOAC adverse events. There were 3 cases of bleeding in the warfarin group. Calcineurin inhibitor levels and estimated glomerular filtration rate did not change significantly in the NOAC group (P = .34 and .96, respectively).

CONCLUSIONS

Compared to warfarin, NOACs are well tolerated and effective for preventing and treating thromboembolic events in renal transplant recipients. A larger randomized controlled study is required.

Safety of direct oral anticoagulants in solid organ transplant recipients: A meta-analysis

There is limited evidence comparing direct oral anticoagulants (DOACs) and warfarin in solid organ transplant (SOT) recipients. We performed a pooled analysis to study the safety and efficacy of DOACs in this patient population. We searched PubMed, Embase, and Scopus databases using the search terms "heart transplant" or "lung transplant" or "liver transplant" or "kidney transplant" or "pancreas transplant" and "direct oral anticoagulant" for literature search. Random effects model with Mantel-Haenszel method was used to pool the outcomes. Pooled analysis included 489 patients, of which 259 patients received DOACs and 230 patients received warfarin. When compared to warfarin, the use of DOACs was associated with decreased risk of composite bleed (RR .49, 95% CI .32-.76, p = .002). There were no differences in rates of major bleeding (RR .55, 95% CI .20-1.49, p = .24) or venous thromboembolism (RR .65, 95% CI .25-1.70, p = .38) between the two groups. Evidence from pooled analysis suggests that DOACs are comparable to warfarin in terms of safety in SOT recipients. Further research is warranted to conclusively determine whether DOACs are safe alternatives to warfarin for anticoagulation in SOT recipients.

Can direct oral anticoagulants be used in kidney transplant recipients?

BACKGROUND

Kidney transplant recipients(KTRs) are at an increased risk of venous thromboembolism (VTE) and atrial fibrillation(AF). Direct oral anticoagulants (DOACs) have shown important advantages over vitamin K antagonists; however, in KTRs, concerns regarding interactions and use in severe kidney disease may limit their use. This evaluation describes a large UK kidney transplant center's experience of DOACs in KTRs with CrCl > 15 mL/min.

METHODS

Electronic records were reviewed for all adult KTRs at Manchester University Foundation Trust Hospitals taking DOACs between January 2018 and October 2020 with VTE or AF. The primary outcome was trough and peak DOAC levels within the expected reference ranges and secondary outcomes included bleeding and thrombotic events.

RESULTS

In 31 KTRs taking DOACS, eight patients had a CrCl < 30 mL/min. Overall, 94% (62/66) of DOAC levels were within the recommended ranges. There were no thrombotic events and four bleeding events (two major and two clinically relevant non-major bleeds). The overall bleeding rate was 6.9 per 100 patient-years at risk.

CONCLUSIONS

There was no evidence of a significant interaction of apixaban or rivaroxaban with CNIs based on expected DOAC and CNI levels. Their use was found to be safe and effective with no VTE events and bleeding episodes similar to published trial data.

Less bleeding associated with apixaban versus other direct acting oral anticoagulation in solid organ transplant recipients

BACKGROUND

The purpose of this study was to evaluate outcomes of bleeding and thrombosis resulting from the use of DOACs in a large cohort of SOT recipients.

METHODS

This was a single center, retrospective cohort study of adult kidney, heart, lung, and liver transplant recipients transplanted between August 2009 and May 2018. Patients were stratified into two groups: those who received apixaban (apixaban group) or those patients receiving either rivaroxaban or dabigatran (non-apixaban group). The primary endpoint was the cumulative incidence of bleeding while receiving DOAC therapy. The secondary endpoints were incidence of major bleeding and thrombosis at any time while receiving DOAC therapy.

RESULTS

A total of 106 patients were included; 70 patients received apixaban and 36 patients received non-apixaban anticoagulation. Cumulative incidence of any bleeding was lower in the apixaban group compared to the non-apixaban group at both 90 days (4.9% versus 16.1%) and 180 days (11.4% versus 24.9%, P = 0.034). Cumulative incidence of major bleeding (P = 0.686) and thrombosis (P = 0.515) were similar between groups. DOAC dosing congruent with the package insert(s) was associated with a lower risk of thrombosis.

CONCLUSION

Apixaban-based anticoagulation was associated with a lower cumulative incidence of any bleeding compared to non-apixaban DOACs. This article is protected by copyright. All rights reserved.

Use of direct-acting oral anticoagulants in solid organ transplantation: A systematic review

The use of direct-acting oral anticoagulants (DOACs) has increased secondary to the mounting evidence for comparable efficacy and potentially superior safety to vitamin K antagonists (VKAs) in the general population. However, insufficient data regarding DOAC use in solid organ transplant (SOT) recipients and numerous pharmacokinetic and pharmacodynamic considerations limit their use in this highly selected patient population. A systematic review of recent clinical evidence on the safety and efficacy of DOACs compared to VKAs in SOT recipients was conducted. Additional considerations including transplant-specific strategies for DOAC reversal and common pharmacokinetic/pharmacodynamic concerns were also reviewed. Although current evidence is limited to single-center retrospective analyses, DOACs, especially apixaban, appear to be a safe and effective alternative to VKAs for SOT recipients with stable graft function and without drug-drug interactions. Reliable data on DOAC reversal at the time of transplant surgery are lacking, and clinicians should consider idarucizumab, andexanet alfa, and other non-specific reversal agents on an individual patient basis. There is no evidence supporting deviations from the Food and Drug Administration labeling recommendations for DOAC dosing in the setting of drug-drug interactions, obesity, and renal function, especially in patients on hemodialysis.