Evaluation of the impact of body mass index on warfarin requirements in hospitalized patients

Warfarin Time in Therapeutic INR Range and Direct Oral Anticoagulant Adherence for Venous Thromboembolism Across the Spectrum of Weight and Body Mass Index: Findings from Veterans Health Administration

The evidence of direct oral anticoagulants (DOACs) usage for venous thromboembolism (VTE) in patients at extremes of body weight or mass index is limited. In such situations, warfarin may be more frequently used. We investigated warfarin time in the therapeutic international normalized ratio range (TTR) and DOAC adherence based on the calculated proportion of days covered (PDC) by pill coverage from a DOAC prescription in patients with VTE across all body sizes. Using data from the Veterans Health Administration (VA), we identified first-time patients with VTE between 2013 and 2018 treated with warfarin or DOACs. We analyzed 28,245 patients with warfarin TTR (N  =  10,167) or DOAC PDC(N  =  18,078). For warfarin-treated patients after index VTE, mean TTR was lower over shorter treatment durations (TTR 30 vs TTR 180 [mean  ±  SD]: 43.8% ± 33.5% vs 58.8% ± 23.5%). Mean TTR over 180 days after VTE was lowest for patients <60 kg (TTR 180 [mean  ±  SD]: <60kg: 49.3% ± 24.2% vs ≥60 to <100 kg: 57.8% ± 23.4%; P < .0001). For DOAC-treated patients over 180 days after index VTE, mean PDC was lowest for patients <60 kg (PDC 180 [mean  ±  SD]: < 60kg: 76.9% ± 33.2% vs ≥ 60 to <100 kg: 83.6% ± 27.7%; P < .0001).Most DOAC-treated patients attained sufficient adherence across the body size spectrum while warfarin-treated patients <60kg were at risk for low TTR.

A Systematic Review of Polygenic Models for Predicting Drug Outcomes

Polygenic models have emerged as promising prediction tools for the prediction of complex traits. Currently, the majority of polygenic models are developed in the context of predicting disease risk, but polygenic models may also prove useful in predicting drug outcomes. This study sought to understand how polygenic models incorporating pharmacogenetic variants are being used in the prediction of drug outcomes. A systematic review was conducted with the aim of gaining insights into the methods used to construct polygenic models, as well as their performance in drug outcome prediction. The search uncovered 89 papers that incorporated pharmacogenetic variants in the development of polygenic models. It was found that the most common polygenic models were constructed for drug dosing predictions in anticoagulant therapies (n = 27). While nearly all studies found a significant association with their polygenic model and the investigated drug outcome (93.3%), less than half (47.2%) compared the performance of the polygenic model against clinical predictors, and even fewer (40.4%) sought to validate model predictions in an independent cohort. Additionally, the heterogeneity of reported performance measures makes the comparison of models across studies challenging. These findings highlight key considerations for future work in developing polygenic models in pharmacogenomic research.

Identifying and managing adverse drug reactions to promote medicines adherence and safety

Unpleasant side effects or adverse drug reactions (ADRs) caused by medicines can have significant effects on people's quality of life and therapeutic outcomes. Knowledge of how ADRs occur enables nurses who prescribe and/or administer medicines to identify and manage them effectively, which can improve the patient experience and increase adherence. This article outlines the types of ADRs and explains how nurses can reduce medicines-related harm by following the principles of medicines optimisation, undertaking regular medication reviews and communicating openly with patients about their medicines.

Warfarin dosing strategies evolution and its progress in the era of precision medicine, a narrative review

Background For decades, vitamin K antagonists and specifically warfarin, have been the sole agents used orally to manage thromboembolic conditions, including stroke and venous thromboembolism (VTE). Several factors lead to warfarin dose variability, including genetic and non-genetic factors which made warfarin management challenging especially at the initiation phase. To overcome the challenges with warfarin dosing at initiation, strategies other than conventional or fixed dosing were introduced and explored. Aim In this narrative review, we aim to discuss and critique the different dosing strategies for warfarin at initiation with more focus on genotype-guided warfarin dosing and the most recent supporting evidence for and against its use. Method Medline database was searched from 1965 to July 2021. Articles addressing different warfarin dosing methods were screened for inclusion. Results A number of methods exist for warfarin initiation. Studies comparing different dosing methods for initiation yielded conflicting outcomes due to differences in study design, population studied, comparator, and outcomes measured. Conclusions Looking at the big picture, the use of genetic dosing for warfarin initiation can lead to better outcomes. Whether these better outcomes are clinically or economically beneficial remains controversial.

Evaluation of Potential Drug Interactions with AiDKlinik® in a Random Population Sample

Purpose

Undesirable drug interactions are frequent, they endanger the success of therapy, and they lead to adverse drug reactions. The present study aimed to evaluate statistically potentially drug interactions in a locally circumscribed, random sample population.

Patients and Methods

In a random sample population of 264 patients taking medications, we performed analyses with the drug information system AiDKlinik^®. Statistical analysis was performed using SAS version 9.4.

Results

Statistically potentially drug interactions were recorded in 82/264 (31.1%) subjects, including 39/82 (47.56%) men, and 43/82 (52.43%) women (χ²= 0.081; p = 0.776). The average number of potential possible interactions detected per person was 1.60 ± 1.21. The regression model with the variables age, body-mass-index and number of long-term-medications shows a significant association between the number of long-term medications taken and the number of moderately severe and severe reactions to drug interactions (F(3.239) = 28.67, p < 0.0001; (t(239) 8.28; p < 0.0001)). After backward elimination, the regression model showed a significant interaction with the number of long-term medications (t (240) = 8.73, p < 0.0001) and body-mass-index (t (240) = 2.02, p = 0.0442). In descriptive analysis, the highest percentages of potential drug interactions occurred in 42/82 (51.22%) subjects with body mass indices (BMIs) >25 kg/m² and in 28/82 (34.15%) subjects aged 61–70 years.

Conclusion

Number of long-term medications use, age, and obesity may lead to increased drug–drug interactions in a random population sample.

Oral anticoagulant use in patients with morbid obesity: A systematic review and meta-analysis

OBJECTIVES

Obesity is associated with increased risks of atrial fibrillation (AF) and venous thromboembolism (VTE) for which anticoagulation is commonly used. However, data on the efficacy and safety of oral anticoagulants in patients with morbid obesity are limited.

METHODS

We conducted a systematic review and meta-analysis to evaluate the efficacy and safety of direct oral anticoagulants (DOACs) or vitamin K antagonists (VKAs) for AF or VTE in patients with morbid obesity.

RESULTS

We included 3 randomized controlled trials (5 studies) and 18 observational studies in adult patients with a body weight ≥ 120 kg, body mass index (BMI) ≥ 40 kg/m2 or classified as morbid obesity who received DOACs or VKAs for AF or VTE (N=77,687). The primary efficacy outcome was stroke/systemic embolism or recurrent VTE, and the primary safety outcome was major bleeding. DOACs were associated with a pooled incidence rate of stroke/systemic embolism of 1.16 per 100 person-years, compared to 1.18 with VKAs. The incidence of recurrent VTE on DOACs was 3.83 per 100 person-years, compared to 6.81 on VKAs. In both VTE and AF populations, DOACs were associated with lower risks of major bleeding compared to VKAs. However, all observational studies had moderate to serious risks of bias.

CONCLUSIONS

Patients with morbid obesity on DOACs had similar risks of stroke/systemic embolism, lower rates of recurrent VTE and major bleeding events compared to those on VKAs. However, the certainty of evidence was low given that studies were mostly observational with high risk of confounding.

Impact of body mass index on 90-day warfarin requirements: a retrospective chart review

Background:

Rates of obesity continue to rise worldwide as evidenced in the 2017 Centers for Disease Control and Prevention (CDC) report that indicated over 35% of United States (US) citizens are obese, with Louisiana ranked as the fifth most obese state in America. Since large clinical trials tend to exclude obese patients, health care providers are faced with concerns of under- or overdosing these patients on warfarin.

Methods:

This retrospective chart review evaluated patients who reported to a community anticoagulation clinic for warfarin management between 1 June 2017 and 30 September 2017. Along with baseline demographics, chronic use of drugs that have clinically significant interactions with warfarin, social activity such as tobacco use and alcohol consumption, were collected. Body mass indexes (BMI) were collected and categorized according to the World Health Organization definitions as follows: Normal (BMI 18–24.9 kg/m²), Overweight (25–29.9 kg/m²), Obesity Class I (30–34.9 kg/m²), Obesity Class II (35–39.9 kg/m²), Obesity Class III (⩾40 kg/m²). The primary outcome was the mean 90-day warfarin dose required to maintain “intermediate control” or “good control” of international normalized ratio (INR), stratified by BMI classifications. The secondary outcome was the time in therapeutic range (TTR) stratified by BMI classifications.

Results:

A total of 433 patient encounters were included in this study. There was a total of 43 encounters in the Normal BMI category, 111 Overweight encounters, 135 Obesity Class I encounters, 45 Obesity Class II encounters, and 99 Obesity Class III encounters. Approximately 63% of the study population were male, and over 90% the patients were African American. The Obesity Class I and Obesity Class II class required an average of 11.47 mg and 17.10 mg more warfarin, respectively, to maintain a therapeutic INR when compared with the Normal BMI category. These findings were statistically significant with p values of 0.007 and <0.001, respectively. Additionally, upon comparing the Overweight BMI category with the Obesity Class II category, there was a mean warfarin dose difference of 11.22 mg (p = 0.010) more in Obesity Class II encounters to maintain a therapeutic INR. In the secondary analysis of TTR, Overweight category encounters had the highest TTR, whereas encounters in the Normal BMI category had the lowest TTR.

Conclusion:

As BMI increases, there is an increased chronic warfarin requirement to maintain “intermediate control” or “good control” of INR between 2 and 3 in an ambulatory care setting.

Recurrent Thrombi in an Obese Patient With History of Bariatric Surgery Despite Anti-Xa Therapy

Obesity and gastric bypass surgery can complicate anticoagulation therapy. In general, patients post-bariatric surgery are considered to be at a moderate risk for deep venous thromboembolism or pulmonary embolism. American Association of Clinical Endocrinologists/American College of Endocrinology, The Obesity Society, American Society for Metabolic & Bariatric Surgery, Obesity Medicine Association, and American Society of Anesthesiologists guidelines recommend chemical prophylaxis with unfractionated heparin or low molecular weight heparin after surgery until the patient is fully mobile, and for those who require chronic anticoagulation, the International Society of Thrombosis and Haemostasis recommend warfarin if body mass index (BMI) is above 40 kg/m² or weight is more than 120 kg. Clinical decision making regarding anticoagulation in the following patient case is complicated by multiple factors, most notably the combination of obesity and history of gastric bypass surgery. This patient failed multiple anticoagulation regimens, with apixaban and rivaroxaban therapies each ending in venous thromboemboli and warfarin leading to subtherapeutic International Normalized Ratio (INR)s despite dose adjustment. However, she is currently therapeutic on the combination of enoxaparin and warfarin as shown by INR and anti-Xa level monitoring. In this case and similar instances, there could be a need for anticoagulant dose adjustments, different INR goals, or a combination of different anticoagulants. Providers should take an individualized approach to patients who have had bariatric surgery with elevated BMI as a key factor in anticoagulant selection.

Direct Oral Anticoagulants in the Treatment of Venous Thromboembolism: Use in Patients with Advanced Renal Impairment, Obesity, or Other Weight-Related Special Populations

There are currently more than 7 million patients taking a direct oral anticoagulant (DOAC), with more new prescriptions per year than warfarin. Despite impressive efficacy and safety data for the treatment of venous thromboembolism, patients with obesity or advanced renal impairment represented a small portion of the patients enrolled in the phase 3 clinical trials. Therefore, to evaluate the potential use of DOACs in these special populations, clinicians need to have an understanding of the pharmacokinetics and pharmacodynamics of these agents in these settings. Since data from randomized controlled trials are limited, data from observational trials are helpful in gaining comfort with the use of DOACs in these special populations. Selecting the appropriate dose for each agent is imperative in achieving optimal patient outcomes. We provide an extensive review of the pharmacokinetics, pharmacodynamics, phase 3 clinical trials, and observational studies on the use of DOACs in patients with advanced renal impairment, obesity, or other weight-related special populations to provide clinicians with a comprehensive understanding of the data for optimal drug and dose selection.

Comparative Effectiveness and Safety of Direct Oral Anticoagulants in Obese Patients with Atrial Fibrillation

BACKGROUND

Unlike warfarin direct oral anticoagulants (DOACs) are administered in fixed doses, which raises concerns of its effectiveness on larger patients. Data from randomized trials are limited on the safety and efficacy of DOACs in morbidly obese individuals with atrial fibrillation (AF).

METHODS

We analyzed a cohort of obese (≥ 120 kg) and morbidly obese (BMI > 40 kg/m²) patients from the Veterans Health Administration system with AF who initiated apixaban, rivaroxaban, dabigatran, or warfarin between years 2012 and 2018. We used inverse probability of treatment weighting (IPTW) and Cox proportional hazards regression models to evaluate the relative hazard of death, myocardial infarction (MI), ischemic stroke, heart failure (HF), and bleeding events between oral anticoagulant (OAC) groups while censoring for medication cessation.

RESULTS

We identified 6052 obese patients on apixaban, 4233 on dabigatran, 4309 on rivaroxaban, and 13,417 on warfarin (mean age 66.7 years, 91% males, 80.4% whites). At baseline patients on apixaban had the lowest glomerular filtration rate and highest rates of previous stroke and MI compared to other OACs. Among patients with weight ≥ 120 kg and those with BMI > 40 kg/m², all DOACs were associated with lower risk of any hemorrhage, hemorrhagic stroke, and gastrointestinal (GI) bleeding. Patients with BMI > 40 kg/m² treated with DOACs had similar ischemic stroke risk with those on warfarin.

CONCLUSIONS

In this large cohort of obese Veterans Health Administration system patients, the use of DOACs resulted in lower hemorrhagic complications than warfarin while maintaining efficacy on ischemic stroke prevention.

Evaluation of the impact of body mass index on venous thromboembolism risk factors

In this paper, we investigate the interaction impacts of body mass index (BMI) on the other important risk factors for venous thromboembolism (VTE), using deep venous thrombosis (DVT) patient data from the International Warfarin Pharmacogenetics Consortium (IWPC). We apply eight machine learning techniques, including naive Bayes classifier (NB), support vector machine (SVM), elastic net regression (ENET), logistic regression (LR), lasso regression (LAR), multivariate adaptive regression splines (MARS), boosted regression tree (BRT) and random forest model (RF). The RF method is selected as the best model for classification. Out of 33 features considered in this study, we identify 12 variables as relatively important risk factors for VTE. Finally, we examine the interaction impacts of BMI on these important VTE risk factors. We conclude that the impacts of risk factors on VTE incidence are varying across different BMI groups, and the variations are different for different risk factors. Therefore the interaction impacts of BMI on the other risk factors have to be taken into account in order to better understand the incidence of VTE.

How to optimise anticoagulation for patients who are obese

Management of anticoagulation has become a hot topic in the last decade. Health-care professionals are encountering increasing number of patients diagnosed with a thromboembolic episode, probably as a result of heightened awareness. In addition, the recognition that hospital-acquired thrombosis causes substantial mortality has led to an emphasis on appropriate thromboprophylaxis in all patients deemed at risk of thrombosis. However, the use of anticoagulants for both treatment and prophylaxis of thrombosis can pose a challenge in individuals who are obese. There are no detailed studies in this area and as such the dosing and monitoring of anticoagulants in these individuals can be problematic.

Identifying mutation-driven changes in gene functionality that lead to venous thromboembolism

Venous thromboembolism (VTE) is a common hematological disorder. VTE affects millions of people around the world each year and can be fatal. Earlier studies have revealed the possible VTE genetic risk factors in Europeans. The 2018 Critical Assessment of Genome Interpretation (CAGI) challenge had asked participants to distinguish between 66 VTE and 37 non-VTE African American (AA) individuals based on their exome sequencing data. We used variants from AA VTE association studies and VTE genes from DisGeNET database to evaluate VTE risk via four different approaches; two of these methods were most successful at the task. Our best performing method represented each exome as a vector of predicted functional effect scores of variants within the known genes. These exome vectors were then clustered with k-means. This approach achieved 70.8% precision and 69.7% recall in identifying VTE patients. Our second-best ranked method had collapsed the variant effect scores into gene-level function changes, using the same vector clustering approach for patient/control identification. These results show predictability of VTE risk in AA population and highlight the importance of variant-driven gene functional changes in judging disease status. Of course, more in-depth understanding of AA VTE pathogenicity is still needed for more precise predictions.

Obesity and Atrial Fibrillation: Epidemiology, Pathophysiology and Novel Therapeutic Opportunities

Obesity is already a major global public health issue, implicated in a vast array of conditions affecting multiple body systems. It is now also firmly established as an independent risk factor in the incidence and progression of AF. The rapidly rising morbidity, mortality and healthcare costs associated with AF despite implementation of the three pillars of AF management — anticoagulation, rate control and rhythm control — suggest other strategies need to be considered. Compelling data has unveiled novel insights into adipose tissue biology and its effect on arrhythmogenesis while secondary prevention strategies targeting obesity as part of a comprehensive risk factor management programme have been demonstrated to be highly effective. Here, the authors review the epidemiological basis of the obesity—AF relationship, consider its underlying pathophysiology and discuss new therapeutic opportunities on the horizon.