Effect of major gastrointestinal tract surgery on the absorption and efficacy of direct acting oral anticoagulants (DOACs)

Practical considerations for the use of direct oral anticoagulants in oncology patients

Oncology patients are at a high risk of experiencing venous thromboembolism. Historically, venous thromboembolisms in cancer patients have been managed with low-molecular-weight heparin on the basis of the CLOT trial published in 2003. However, recent prospective data provide evidence for safe and effective direct oral anticoagulant use in this population. The purpose of this review article is to evaluate the current body of literature surrounding direct oral anticoagulant use in the oncology population and to highlight key practical considerations when prescribing these agents for patients with cancer.

Gastrointestinal and liver diseases and atrial fibrillation: a review of the literature

Atrial fibrillation (AF) is the most common arrhythmia worldwide and is associated with significant morbidity and mortality. A number of risk factors have been associated with AF, though few studies have explored the association between gastrointestinal and liver diseases and AF. Additionally, AF and treatment for AF may predispose to gastrointestinal and liver diseases. We review the current literature on the bidirectional associations between gastrointestinal and liver diseases and AF. We highlight the gaps in knowledge and areas requiring future investigation.

Current Management of Cancer-associated Venous Thromboembolism: Focus on Direct Oral Anticoagulants

Cancer-associated venous thromboembolism (CAT) is a common complication associated with high morbidity and mortality. In accordance with major clinical trials comparing low-molecular-weight heparin (LMWH) with a vitamin K antagonist (VKA), LMWH is currently the standard treatment for CAT, owing to its efficacy for thrombosis recurrence and improved safety profile compared to VKA. Over the past few years, direct oral anticoagulants (DOACs) have emerged as potential alternative therapies to LMWH due to their convenient route of administration and predictable pharmacokinetics, but evidence for their use in CAT is inconclusive, as only a small fraction of the study populations in these trials had CAT. Recently, two large head-to-head trials comparing DOACs to LMWH in CAT patients reported comparable efficacies of DOACs with increased bleeding risk. Occasionally, CAT treatment can be challenging due to the heterogeneity of underlying malignancies and comorbidities. Renal insufficiency and gastrointestinal defects are the main obstacles in anticoagulant selection. Careful choice of treatment candidates and proper anticoagulant strategies are critical for the treatment of CAT; hence, more studies are required to address these challenges.

Direct Oral Anticoagulant Drugs: On the Treatment of Cancer-Related Venous Thromboembolism and their Potential Anti-Neoplastic Effect

Cancer patients develop a hypercoagulable state with a four- to seven-fold higher thromboembolic risk compared to non-cancer patients. Thromboembolic events can precede the diagnosis of cancer, but they more often occur at diagnosis or during treatment. After malignancy itself, they represent the second cause of death. Low molecular weight heparins are the backbone of the treatment of cancer-associated thromboembolism. This treatment paradigm is possibly changing, as direct oral anticoagulants (DOACs) may prove to be an alternative therapeutic option. The currently available DOACs were approved during the first and second decades of the 21st century for various clinical indications. Three molecules (apixaban, edoxaban and rivaroxaban) are targeting the activated factor X and one (dabigatran) is directed against the activated factor II, thrombin. The major trials analyzed the effect of these agents in the general population, with only a small proportion of cancer patients. Two published and several ongoing studies are specifically investigating the use of DOACs in cancer-associated thromboembolism. This article will review the current available literature on the use of DOACs in cancer patients. Furthermore, we will discuss published data suggesting potential anti-cancer actions exerted by non-anticoagulant effects of DOACs. As soon as more prospective data becomes available, DOACs are likely to be considered as a potential new therapeutic option in the armamentarium for patients suffering of cancer-associated thromboembolism.

Treatment algorithm in cancer-associated thrombosis: Canadian expert consensus

Management of anticoagulant therapy for the treatment of venous thromboembolism (vte) in cancer patients is complex because of an increased risk of recurrent vte and major bleeding complications in those patients relative to the general population. Subgroups of patients with cancer also show variation in their risk for recurrent vte and adverse bleeding events. Accordingly, a committee of 10 Canadian clinical experts developed the consensus risk- stratification treatment algorithm presented here to provide guidance on tailoring anticoagulant treatment choices for the acute and extended treatment of symptomatic and incidental vte, to prevent recurrent vte, and to minimize the bleeding risk in patients with cancer. During a 1-day live meeting, a systematic review of the literature was performed, and a draft treatment algorithm was developed. The treatment algorithm was refined through the use of a Web-based platform and a series of online teleconferences. Clinicians using this treatment algorithm should consider the bleeding risk, the type of cancer, and the potential for drug-drug interactions in addition to informed patient preference in determining the most appropriate treatment for patients with cancer-associated thrombosis. Anticoagulant therapy should be regularly reassessed as the patient's cancer status and management change over time.

The Role of Direct Oral Anticoagulants in Treatment of Cancer-Associated Thrombosis

Venous thromboembolism (VTE) complicates the clinical course of approximately 5–10% of all cancer patients. Anticoagulation of the cancer patient often presents unique challenges as these patients have both a higher risk of recurrent VTE and a higher risk of bleeding than patients without cancer. Although low molecular weight heparins (LMWH) are the standard of care for the management of cancer-associated VTE, their use requires once or twice daily subcutaneous injections, which can be a significant burden for many cancer patients who often require a long duration of anticoagulation. The direct oral anticoagulants (DOACs) are attractive options for patients with malignancy. DOACs offer immediate onset of action and short half-lives, properties similar to LMWH, but the oral route of administration is a significant advantage. Given the higher risks of recurrent VTE and bleeding, there has been concern about the efficacy and safety of DOACs in this patient population. Data are now emerging for the use of DOACs in the cancer patient population from dedicated clinical trials. While recently published data suggest that DOACs hold promise for the treatment of cancer associated VTE, additional studies are needed to establish DOACs as the standard-of-care treatment. Many such studies are currently underway. The available data for the use of DOACs in the treatment of cancer-associated VTE will be reviewed, focusing on efficacy, safety, and other considerations relevant to the cancer patient.

Intestinal failure: a review

Intestinal failure (IF) is the inability of the gut to absorb necessary water, macronutrients (carbohydrate, protein, and fat), micronutrients, and electrolytes sufficient to sustain life and requiring intravenous supplementation or replacement. Acute IF (types 1 and 2) is the initial phase of the illness and may last for weeks to a few months, and chronic IF (type 3) from months to years. The challenge of caring for patients with IF is not merely the management of the underlying condition leading to IF or the correct provision of appropriate nutrition or both but also the prevention of complications, whether thromboembolic phenomenon (for example, venous occlusion), central venous catheter-related bloodstream infection, IF-associated liver disease, or metabolic bone disease. This review looks at recent questions regarding chronic IF (type 3), its diagnosis and management, the role of the multidisciplinary team, and novel therapies, including hormonal treatment for short bowel syndrome but also surgical options for intestinal lengthening and intestinal transplant.

Warfarin Dose Adjustment After Biliopancreatic Diversion/Duodenal Switch Bariatric Surgery

BACKGROUND

The absorption of drugs and fat-soluble vitamins is impaired after bariatric surgery on which intestinal length and function are altered. In this context, the anticoagulant effect of warfarin is difficult to predict in the postoperative period.

OBJECTIVE

This study aimed at describing the average weekly warfarin dose required to maintain a therapeutic international normalized ratio (INR) before and up to 1 year after sleeve gastrectomy with biliopancreatic diversion and duodenal switch (BPD/DS). Secondary end points included the number of patients requiring a minimal 20% reduction in their weekly dose of warfarin following the BPD/DS.

METHODS

This descriptive and retrospective longitudinal population study included 20 patients using warfarin who underwent BPD/DS. An INR was considered nontherapeutic if it was below or above 15% of the targeted therapeutic range for any given patient.

RESULTS

One month after the surgery, the median weekly dose of warfarin was 55% lower than the preoperative dose ( P < 0.0001). In the 9 patients with full follow-up data, the warfarin dose at 1 year was still 39% lower than the preoperative dose ( P < 0.05). At that time, all patients presented a minimal dose reduction of 20%.

CONCLUSIONS

BPD/DS robustly reduced the requirement of warfarin, which resulted in lower doses after surgery. This persisted over the first year after the surgery, likely because of enhanced sensitivity. The mechanisms for this effect remain multifactorial, and the exact extent of change in dose cannot be predicted.

Cancer-Associated Venous Thromboembolism: A Practical Review Beyond Low-Molecular-Weight Heparins

Patients with cancer are at significantly higher risk of developing, and dying from, venous thromboembolism (VTE). The CLOT trial demonstrated superiority of low-molecular-weight heparins (LMWH) over warfarin for recurrent VTE and established LMWH as the standard of care for cancer-associated VTE. However, with patients living longer with metastatic cancer, long-term injections are associated with significant cost and injection fatigue. Direct oral anticoagulants (DOACs) are an attractive alternative for treatment of cancer-associated VTE. Meta-analysis of subgroup data of patients with cancer from the large DOAC VTE trials and small non-randomized studies have found no difference in VTE recurrence or major bleeding. With this limited evidence, clinicians may decide to switch their patients who require long-term anticoagulation from LMWH to a DOAC. This requires careful consideration of the interplay between the patient's cancer and treatment course, with their underlying comorbidities.

How I treat recurrent venous thromboembolism in patients receiving anticoagulant therapy

Oral anticoagulant therapy for venous thromboembolism is very effective. When oral anticoagulants are managed well, the risk of recurrence is approximately 2 per 100 patient-years. The main reasons for a breakthrough event are underlying disease and subtherapeutic drug levels. The most common underlying disease that results in recurrence on treatment is cancer. Subtherapeutic drug levels can be caused by poor adherence to the drug regimen, interactions with other drugs or food, or inappropriate dosing. It is important to investigate and understand the cause whenever such an event occurs and to improve management of anticoagulants thereby avoiding further recurrences. Here we present 4 illustrative cases together with a discussion of the underlying pathology. Whereas the mechanisms are usually quite well understood, the management of further anticoagulation after a breakthrough event is based on minimal or no clinical trial evidence.