Low ectonucleotidase activity and increased neutrophil-platelet aggregates in patients with antiphospholipid syndrome.

ABSTRACT: Many patients with antiphospholipid syndrome had decreased ectonucleotidase activity on neutrophils and platelets, which enabled extracellular nucleotides to trigger neutrophil-platelet aggregates. This phenotype was replicated by treating healthy neutrophils and platelets with patient-derived antiphospholipid antibodies or ectonucleotidase inhibitors.

Update on Guidelines for the Prevention of Cancer-Associated Thrombosis.

Patients with cancer are at high risk of developing arterial and venous thromboembolism (VTE). They constitute 15% to 20% of the patients diagnosed with VTE. Depending on the type of tumor, cancer therapy, and presence of other risk factors, 1% to 25% of patients with cancer will develop thrombosis. The decision to start patients with cancer on primary thromboprophylaxis depends on patient preference, balancing risk of bleeding versus risk of thrombosis, cost, and adequate organ function. Currently, guidelines recommend against the use of routine primary thromboprophylaxis in unselected ambulatory patients with cancer. Validated risk assessment models can accurately identify patients at highest risk for cancer-associated thrombosis (CAT). This review summarizes the recently updated NCCN Guidelines for CAT primary prophylaxis, with a primarily focus on VTE prevention. Two main clinical questions that providers commonly encounter will also be addressed: which patients with cancer should receive primary thromboprophylaxis (both surgical and medical oncology patients) and how to safely choose between different anticoagulation agents.

A survey of internists' recommendations for aspirin in older adults and barriers to evidence-based use.

Recent trials suggest that aspirin for primary prevention may do more harm than good for some, including adults over 70 years of age. We sought to assess how primary care providers (PCPs) use aspirin for the primary prevention in older patients and to identify barriers to use according to recent guidelines, which recommend against routine use in patients over age 70. We surveyed PCPs about whether they would recommend aspirin in clinical vignettes of a 75-year-old patient with a 10-year atherosclerotic cardiovascular disease risk of 25%. We also queried perceived difficulty following guideline recommendations, as well as perceived barriers and facilitators. We obtained responses from 372 PCPs (47.9% response). In the patient vignette, 45.4% of clinicians recommended aspirin use, which did not vary by whether the patient was using aspirin initially (p = 0.21); 41.7% believed aspirin was beneficial. Perceived barriers to guideline-based aspirin use included concern about patients being upset (41.6%), possible malpractice claims (25.0%), and not having a strategy for discussing aspirin use (24.5%). The estimated adjusted probability of rating the guideline as "hard to follow" was higher in clinicians who believed aspirin was beneficial (29.4% vs. 8.0%; p < 0.001) and who worried the patient would be upset if told to stop aspirin (26.7% vs. 12.5%; p = 0.001). Internists vary considerably in their recommendations for aspirin use for primary prevention in older patients. A high proportion of PCPs continue to believe aspirin is beneficial in this setting. These results can inform de-implementation efforts to optimize evidence-based aspirin use.

How to Choose An Appropriate Anticoagulant for Cancer-Associated Thrombosis.

Venous thromboembolic disease can be a fatal complication of cancer. Despite advances in prevention, thousands of patients require treatment of cancer-associated thrombosis (CAT) each year. Guidelines have advocated low-molecular-weight heparin (LMWH) as the preferred anticoagulant for CAT for years, based on clinical trial data showing LMWH to be associated with a lower risk of recurrent thrombosis when compared with vitamin K antagonists. However, the potentially painful, subcutaneously administered LMWH injections can be expensive, and clinical practice has not been consistent with guideline recommendations. Recently, studies have compared LMWH to the direct oral anticoagulants (DOACs) for the management of CAT. Based on promising trial results outlined in this review, DOACs are now preferred anticoagulants for CAT occurring in patients without gastric or gastroesophageal lesions. For patients with gastrointestinal cancers, who may be at higher risk of hemorrhage with the DOACs, LMWH remains the anticoagulant of choice. Applying the latest data from this rapidly evolving field to care for diverse patient groups can be challenging. This article provides an evidence-based review of outpatient anticoagulant selection for lower-extremity deep vein thrombosis or pulmonary embolism in the setting of cancer, and takes into account special populations with cancer.

Clinical and sociodemographic factors associated with anticoagulant use for cancer associated venous thromboembolism.

Cancer associated thrombosis (CAT) is a leading cause of death among patients with cancer. It is not clear if non-clinical factors are associated with anticoagulation receipt. We conducted a retrospective cohort study of Optum's de-identified Clinformatics® Database of adults with cancer diagnosed between 2009 and 2016 who developed CAT, treated with an outpatient anticoagulant (warfarin, low molecular weight heparin (LMWH), or a direct oral anticoagulant (DOAC)). Of 12,622 patients, three months after an episode of CAT, 1,485 (12%) were on LMWH, 1,546 (12%) on DOACs, and 9,591 (76%) were on warfarin. When controlling for other factors, anticoagulant use was significantly associated with socioeconomic factors, region, co-morbidities, type of thrombosis, and cancer subtype. Patients with a bachelor's degree or greater level of education were less likely to receive warfarin (OR: 0.77; 95% CI: [0.59, 0.99]; p < 0.046) or DOACs (OR: 0.67; 95% CI: [0.55, 0.82]; p < 0.001) compared to LMWH. Patients with higher income levels were more likely to receive LMWH or DOACs compared to warfarin, while patients across all income levels were equally likely to receive LMWH or DOACs. Non-clinical factors including income, education, and region, are associated with anticoagulation receipt three months after an episode of CAT. Sociodemographic factors may result in some patients receiving suboptimal care and contribute to non-guideline concordant care for CAT.

Cost-effectiveness analysis of low-dose direct oral anticoagulant (DOAC) for the prevention of cancer-associated thrombosis in the United States.

BACKGROUND: Randomized controlled trials (RCTs) have demonstrated that low-dose direct oral anticoagulants (DOACs), including rivaroxaban and apixaban, may help reduce the incidence of cancer-associated venous thromboembolism (VTE). METHODS: A cost-utility analysis was performed from the health sector perspective using a Markov state-transition model in patients with cancer who are at intermediate-to-high risk for VTE. Transition probability, relative risk, cost, and utility inputs were obtained from a meta-analysis of the RCTs and relevant epidemiology studies. Differences in cost, quality-adjusted life-years (QALYs), and the incremental cost-effectiveness ratio (ICER) per patient were calculated over a lifetime horizon. One-way, probabilistic, and scenario sensitivity analyses were conducted. RESULTS: In patients with cancer at intermediate-to-high risk for VTE, treatment with low-dose DOAC thromboprophylaxis for 6 months, compared with placebo, was associated with 32 per 1000 fewer VTE and 11 per 1000 more major bleeding episodes over a lifetime. The incremental cost and QALY increases were $1445 and 0.12, respectively, with an ICER of $11,947 per QALY gained. Key drivers of ICER variations included the relative risks of VTE and bleeding as well as drug cost. This strategy was 94% cost effective at the threshold of $50,000 per QALY. The selection of patients with Khorana scores ≥3 yielded the greatest value, with an ICER of $5794 per QALY gained. CONCLUSIONS: Low-dose DOAC thromboprophylaxis for 6 months appears to be cost-effective in patients with cancer who are at intermediate-to-high risk for VTE. The implementation of this strategy in patients with Khorana scores ≥3 may lead to the highest cost-benefit ratio.

Identification of undocumented over-the-counter medications in an academic nephrology clinic.

OBJECTIVES: To explore how accurately over-the-counter (OTC) medications were documented in an academic nephrology clinic and the benefits of using a novel short questionnaire as part of medication reconciliation (MR). METHODS: We developed a 3-item tailored questionnaire with questions about use of aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), and proton pump inhibitors (PPIs), which clinical leadership identified as medications of interest. Over the course of 20 days, medical assistants administered the questionnaire to clinic patients immediately after the standard MR. We summarized the rate of inaccurate medication documentation by individual drug and drug class, comparing the standard MR process with the questionnaire. We also calculated diagnostic performance characteristics of the questionnaire. We evaluated the severity of drug-drug interactions between OTC medications discovered using the OTC medication questionnaire and patients' other prescription medications. RESULTS: Nearly 30% (n = 133 of 450) of the participants had at least 1 inaccurately documented OTC medication after the standard MR. The sensitivity and specificity of the standard MR were 79.2% and 93.5%, respectively, for aspirin; 14.5% and 99.5% for NSAIDs; and 80.4% and 97.3% for PPIs. Medication omissions were resolved in the electronic health record approximately two-thirds of the time using the questionnaire. At least 1 drug-drug interaction (DDI) involving active use of an OTC medication was identified in 9.6% of the patients. Of the DDIs, the most common portended effects were increased nephrotoxicity (52.9%), increased bleeding risk (22.9%), and enhanced antiplatelet activity (7.1%). CONCLUSION: Despite the standard MR process, inaccurate documentation of commonly used OTC medications occurred in nearly one-third of outpatients in a nephrology clinic. A brief OTC medication questionnaire may be a scalable and effective strategy to address this problem.

New biomarkers and imaging approaches for the diagnosis of deep venous thrombosis.

PURPOSE OF REVIEW: Symptoms suggestive of deep vein thrombosis (DVT) are extremely common in clinical practice, but unfortunately nonspecific. In both ambulatory and inpatient settings, clinicians are often tasked with evaluating these concerns. Here, we review the most recent advances in biomarkers and imaging to diagnose lower extremity DVT. RECENT FINDINGS: The modified Wells score remains the most supported clinical decision rule for risk stratifying patients. In uncomplicated patients, the D-dimer can be utilized with risk stratification to reasonably exclude lower extremity DVT in some patients. Although numerous biomarkers have been explored, soluble P-selectin has the most promise as a novel marker for DVT. Imaging will be required for many patients and ultrasound is the primary modality. Nuclear medicine techniques are under development, and computed tomography (CT) and magnetic resonance venography are reasonable alternatives in select patients. SUMMARY: D-dimer is the only clinically applied biomarker for DVT diagnosis, with soluble P-selectin a promising novel biomarker. Recent studies have identified several other potential biomarkers. Ultrasound remains the imaging modality of choice, but CT, MRI, or nuclear medicine tests can be considered in select scenarios.

How to choose appropriate direct oral anticoagulant for patient with nonvalvular atrial fibrillation.

The novel oral anticoagulants or direct oral anticoagulants (DOAC) are becoming more common in clinical practice for the prevention of stroke in non-valvular atrial fibrillation (NVAF). The availability of several agents with similar efficacy and safety for stroke prevention in NVAF patients offers more selection, but at the same time requires certain knowledge to make a good choice. This comparative analysis provides an appraisal of the respective clinical trials and highlights much of what remains unknown about four FDA-approved agents: dabigatran, apixaban, rivaroxaban, and edoxaban. It details how the DOACs compare to warfarin and to one another summarizes pharmacologic and pharmacodynamic properties, and drug interactions from the stand point of practical consequences of these findings. Common misconceptions and reservations are addressed. The practical application of this data is intended to help choosing the most appropriate agent for individual NVAF patient.

Prevalence of Guideline-Discordant Aspirin Use and Associated Adverse Events in Patients on Warfarin for Mechanical Valve Replacement.

BACKGROUND: For patients on warfarin for mechanical heart valve replacement, the 2020 American College of Cardiology and American Heart Association Guidelines recommend only adding aspirin in patients with a specific indication for antiplatelet therapy. This contrasts with prior guidelines, which recommended concomitant aspirin therapy. We sought to assess the prevalence of guideline-discordant aspirin use among patients on warfarin for mechanical heart valve replacement and to compare adverse event rates among patients with and without concomitant aspirin. METHODS: Patients on warfarin for mechanical heart valve replacement were identified from the Michigan Anticoagulation Quality Improvement Initiative registry. Patients with myocardial infarction, percutaneous coronary intervention, or coronary artery bypass within the past 12 months were excluded. Patients were divided into 2 groups based on aspirin use. Patient characteristics and bleeding and thromboembolic outcomes were compared. RESULTS: Four hundred forty-four patients met the inclusion criteria, with 341 (76.8%) on concomitant aspirin. The aspirin group was older (50.6 vs 46.3 years, P = .028) and had more hypertension (57.8% vs 46.6%, P = .046) but other patient characteristics were similar. The aspirin group had a higher rate of bleeding events (28.3 vs 13.3 per 100 patient-years, P < .001) and bleed-related emergency department visits (11.8 vs 2.9 per 100 patient-years, P = .001) compared with the non-aspirin group. There was no observed difference in rates of ischemic stroke (0.56 vs 0.48 per 100 patient-years, P = .89). CONCLUSIONS: A significant proportion of patients on warfarin for mechanical heart valve replacement are on guideline-discordant aspirin. Aspirin deprescribing in select patients may safely reduce bleeding events.

Factors associated with venous thromboembolism pharmacoprophylaxis initiation in hospitalized medical patients: the Medical Inpatients Thrombosis and Hemostasis study.

BACKGROUND: Although guidelines recommend risk assessment for hospital-acquired venous thromboembolism (HA-VTE) to inform prophylaxis decisions, studies demonstrate inappropriate utilization of pharmacoprophylaxis in hospitalized medical patients. Predictors of pharmacoprophylaxis initiation in medical inpatients remain largely unknown. OBJECTIVES: To determine factors associated with HA-VTE pharmacoprophylaxis initiation in adults hospitalized on medical services. METHODS: We performed a cohort study using electronic health record data from adult patients hospitalized on medical services at 4 academic medical centers between 2016 and 2019. Main measures were candidate predictors of HA-VTE pharmacoprophylaxis initiation, including known HA-VTE risk factors, predicted HA-VTE risk, and bleeding diagnoses present on admission. RESULTS: Among 111 550 admissions not on intermediate or full-dose anticoagulation, 48 520 (43.5%) received HA-VTE pharmacoprophylaxis on the day of or the day after admission. After adjustment for age, sex, race/ethnicity, and study site, the strongest clinical predictors of HA-VTE pharmacoprophylaxis initiation were malnutrition and chronic obstructive pulmonary disease. Thrombocytopenia and history of gastrointestinal bleeding were associated with decreased odds of HA-VTE pharmacoprophylaxis initiation. Patients in the highest 2 tertiles of predicted HA-VTE risk were less likely to receive HA-VTE pharmacoprophylaxis than patients in the lowest (first) tertile (OR, 0.84; 95% CI, 0.81-0.86 for the second tertile; OR, 0.95; 95% CI, 0.92-0.98 for the third tertile). CONCLUSION: Among patients not already receiving anticoagulants, HA-VTE pharmacoprophylaxis initiation during the first 2 hospital days was lower in patients with a higher predicted HA-VTE risk and those with risk factors for bleeding. Reasons for not initiating pharmacoprophylaxis in those with a higher predicted HA-VTE risk could not be assessed.

Outcomes of direct oral anticoagulants with aspirin vs warfarin with aspirin: a registry-based cohort study.

Background: For patients anticoagulated with direct oral anticoagulants (DOACs) or warfarin and on aspirin (ASA) for nonvalvular atrial fibrillation and/or venous thromboembolism, it is unclear if bleeding outcomes differ. Objectives: To assess bleeding rates for ASA with DOACs vs warfarin and one another. Methods: Registry-based cohort study of patients followed by a 6-center quality improvement collaborative in Michigan using data from 2009 to 2022. The study included adults on ASA with warfarin or DOACs for atrial fibrillation and/or venous thromboembolism without a recent myocardial infarction or heart valve replacement. Results: After propensity matching by anticoagulant class, we compared 2 groups of 1467 patients followed for a median of 18.0 months. Any bleeding and nonmajor bleeding was increased with DOACs + ASA compared with warfarin + ASA (32.2 vs 27.8 and 27.1 vs 22.9 events/100 patient-years; relative risks [RRs], 1.1 and 1.2; 95% CIs, 1.1-1.2 and 1.1-1.3, respectively). After matching by drug, patients on apixaban + ASA vs warfarin + ASA had more bleeding (31.2 vs 27.8 events/100 patient-years; RR, 1.1; 95% CI, 1.0-1.2) and nonmajor bleeding but less major bleeding (3.8 vs 4.7 events/100 patient-years; RR, 0.8; 95% CI, 0.6-1.0) and emergency room visits for bleeding. Patients on rivaroxaban + ASA vs warfarin + ASA had more bleeding (39.3 vs 26.3 events/100 patient-years, RR, 1.5; 95% CI, 1.3-1.6), nonmajor bleeding, and thrombosis. Patients on apixaban + ASA vs rivaroxaban + ASA had significantly less bleeding (22.5 vs 39.3/100 patient-years; RR, 0.6; 95% CI, 0.5-0.7), nonmajor bleeding, major bleeding (2.1 vs 5.5 events/100 patient-years; RR, 0.4; 95% CI, 0.2-0.6), emergency room visits for bleeding, and thrombotic events. Conclusion: Patients on DOAC + ASA without a recent myocardial infarction or heart valve replacement had more nonmajor bleeding but otherwise similar outcomes compared with warfarin + ASA. Patients treated with rivaroxaban + ASA experienced more adverse clinical events compared with warfarin + ASA or apixaban + ASA.

Guideline Concordance of Aspirin Use for Primary Prevention in Adult Outpatients.

Recent guidelines have recommended a reduced role for primary prevention aspirin use, which is associated with increased bleeding risk. This study seeks to characterize guideline-discordant aspirin use among adults in a community care setting. As part of a quality improvement initiative, patients at one internal medicine and one family medicine clinic affiliated with an academic hospital were sent an electronic survey. Patients were included if they were at least 40 years old, had a primary care provider at the specified sites, and were seen in the last year. Patients were excluded if they had an indication for aspirin other than primary prevention. Responses were collected from February 15 to March 16, 2022. Analyses were performed to identify predictors of primary prevention aspirin use and predictors of guideline-discordant aspirin; aspirin users and non-users were compared using Fisher's exact test, independent samples t-tests, and multivariable logistic regression. Of 1460 patients sent a survey, 668 (45.8%) responded. Of respondents, 132 (24.1%) reported aspirin use that was confirmed to be for primary prevention. Overall, 46.2-58.3% of primary prevention aspirin users were potentially taking aspirin contrary to guideline recommendations. Predictors of discordant aspirin use included a history of diabetes mellitus and medication initiation by a primary care provider. In conclusion, primary prevention aspirin use may be overutilized and discordant with recent guideline recommendations for about half of patients, suggesting a need for aspirin de-implementation. These efforts may be best focused at the primary care level.

Development and validation of a risk model for hospital-acquired venous thrombosis: the Medical Inpatients Thrombosis and Hemostasis study.

BACKGROUND: Regulatory organizations recommend assessing hospital-acquired (HA) venous thromboembolism (VTE) risk for medical inpatients. OBJECTIVES: To develop and validate a risk assessment model (RAM) for HA-VTE in medical inpatients using objective and assessable risk factors knowable at admission. METHODS: The development cohort included people admitted to medical services at the University of Vermont Medical Center (Burlington, Vermont) between 2010 and 2019, and the validation cohorts included people admitted to Hennepin County Medical Center (Minneapolis, Minnesota), University of Michigan Medical Center (Ann Arbor, Michigan), and Harris Health Systems (Houston, Texas). Individuals with VTE at admission, aged <18 years, and admitted for <1 midnight were excluded. We used a Bayesian penalized regression technique to select candidate HA-VTE risk factors for final inclusion in the RAM. RESULTS: The development cohort included 60 633 admissions and 227 HA-VTE, and the validation cohorts included 111 269 admissions and 651 HA-VTE. Seven HA-VTE risk factors with t statistics ≥1.5 were included in the RAM: history of VTE, low hemoglobin level, elevated creatinine level, active cancer, hyponatremia, increased red cell distribution width, and malnutrition. The areas under the receiver operating characteristic curve and calibration slope were 0.72 and 1.10, respectively. The areas under the receiver operating characteristic curve and calibration slope were 0.70 and 0.93 at Hennepin County Medical Center, 0.70 and 0.87 at the University of Michigan Medical Center, and 0.71 and 1.00 at Harris Health Systems, respectively. The RAM performed well stratified by age, sex, and race. CONCLUSION: We developed and validated a RAM for HA-VTE in medical inpatients. By quantifying risk, clinicians can determine the potential benefits of measures to reduce HA-VTE.

Calprotectin Impairs Platelet Survival in Patients With Primary Antiphospholipid Syndrome.

OBJECTIVE: While thrombosis and pregnancy loss are the best-known clinical features of antiphospholipid syndrome (APS), many patients also exhibit "extra-criteria" manifestations, such as thrombocytopenia. The mechanisms that drive APS thrombocytopenia are not completely understood, and no clinical biomarkers are available for predicting antiphospholipid antibody (aPL)-mediated thrombocytopenia. Calprotectin is a heterodimer of S100A8 and S100A9 that is abundant in the neutrophil cytoplasm and released upon proinflammatory neutrophil activation. Here, we sought to evaluate the presence, clinical associations, and potential mechanistic roles of circulating calprotectin in a cohort of primary APS and aPL-positive patients. METHODS: Levels of circulating calprotectin were determined in plasma by the QUANTA Flash chemiluminescent assay. A viability dye-based platelet assay was used to assess the potential impact of calprotectin on aPL-mediated thrombocytopenia. RESULTS: Circulating calprotectin was measured in 112 patients with primary APS and 30 aPL-positive (without APS criteria manifestations or lupus) patients as compared to patients with lupus (without APS), patients with unprovoked venous thrombosis (without aPL), and healthy controls. Levels of calprotectin were higher in patients with primary APS and aPL-positive patients compared to healthy controls. After adjustment for age and sex, calprotectin level correlated positively with absolute neutrophil count (r = 0.41, P < 0.001), positively with C-reactive protein level (r = 0.34, P = 0.002), and negatively with platelet count (r = -0.24, P = 0.004). Mechanistically, we found that calprotectin provoked aPL-mediated thrombocytopenia by engaging platelet surface toll-like receptor 4 and activating the NLRP3-inflammasome, thereby reducing platelet viability in a caspase-1-dependent manner. CONCLUSION: These data suggest that calprotectin has the potential to be a functional biomarker and a new therapeutic target for APS thrombocytopenia.

Neutrophil glucose flux as a therapeutic target in antiphospholipid syndrome.

Neutrophil hyperactivity and neutrophil extracellular trap release (NETosis) appear to play important roles in the pathogenesis of the thromboinflammatory autoimmune disease known as antiphospholipid syndrome (APS). The understanding of neutrophil metabolism has advanced tremendously in the past decade, and accumulating evidence suggests that a variety of metabolic pathways guide neutrophil activities in health and disease. Our previous work characterizing the transcriptome of APS neutrophils revealed that genes related to glycolysis, glycogenolysis, and the pentose phosphate pathway (PPP) were significantly upregulated. Here, we found that neutrophils from patients with APS used glycolysis more avidly than neutrophils from people in the healthy control group, especially when the neutrophils were from patients with APS with a history of microvascular disease. In vitro, inhibiting either glycolysis or the PPP tempered phorbol myristate acetate- and APS IgG-induced NETosis, but not NETosis triggered by a calcium ionophore. In mice, inhibiting either glycolysis or the PPP reduced neutrophil reactive oxygen species production and suppressed APS IgG-induced NETosis ex vivo. When APS-associated thrombosis was evaluated in mice, inhibiting either glycolysis or the PPP markedly suppressed thrombosis and circulating NET remnants. In summary, these data identify a potential role for restraining neutrophil glucose flux in the treatment of APS.

Factors Associated With Inferior Vena Cava Filter Placement and Retrieval for Patients With Cancer-Associated Thrombosis.

BACKGROUND: Venous thromboembolism is a leading cause of death in patients with cancer. Inferior vena cava filters are utilized to mitigate the risk of pulmonary embolism for patients who have contraindication to, or failure of, anticoagulation. METHODS: We reviewed an insurance claims database to identify adults receiving cancer-directed therapy and had a new diagnosis of venous thromboembolism. We then evaluated clinical and sociodemographic characteristics in patients with and without filter placement and retrieval. RESULTS: There were 25,788 patients (mean [SD] age: 68.3 [12.7] years) who met the study inclusion criteria, with 2111 individuals (8.2%) undergoing filter placement. Filter placement was associated with the type of thrombosis, malignancy, recent surgery, comorbidities, and income. A total of 137 patients (6.5%) newly started anticoagulation within 3 days of filter placement, and 612 (29%) patients received anticoagulation within 30 days after filter placement. Despite this, only 159 (7.5%) patients had their filters retrieved during the study period. Patients with income of $75-99K (odds ratio 2.13, P = .012) or above $100K (odds ratio 1.8, P = .038) were more likely to have filter retrieval compared with those with income <$50K. Filter retrieval was also more likely in younger patients and those with fewer comorbidities or without central nervous system or lung malignancies. CONCLUSIONS: Inferior vena cava filter placement and retrieval are associated with several sociodemographic factors. Filter retrieval rates are low despite re-initiation of anticoagulation in many patients. Efforts are needed to address disparities in filter use and improve retrieval rates.

Assessment of an Intervention to Reduce Aspirin Prescribing for Patients Receiving Warfarin for Anticoagulation.

Importance: For some patients receiving warfarin, adding aspirin (acetylsalicylic acid) increases bleeding risk with unclear treatment benefit. Reducing excess aspirin use could be associated with improved clinical outcomes. Objective: To assess changes in aspirin use, bleeding, and thrombosis event rates among patients treated with warfarin. Design, Setting, and Participants: This pre-post observational quality improvement study was conducted from January 1, 2010, to December 31, 2019, at a 6-center quality improvement collaborative in Michigan among 6738 adults taking warfarin for atrial fibrillation and/or venous thromboembolism without an apparent indication for concomitant aspirin. Statistical analysis was conducted from November 26, 2020, to June 14, 2021. Intervention: Primary care professionals for patients taking aspirin were asked whether an ongoing combination aspirin and warfarin treatment was indicated. If not, then aspirin was discontinued with the approval of the managing clinician. Main Outcomes and Measures: Outcomes were assessed before and after intervention for the primary analysis and before and after 24 months before the intervention (when rates of aspirin use first began to decrease) for the secondary analysis. Outcomes included the rate of aspirin use, bleeding, and thrombotic outcomes. An interrupted time series analysis assessed cumulative monthly event rates over time. Results: A total of 6738 patients treated with warfarin (3160 men [46.9%]; mean [SD] age, 62.8 [16.2] years) were followed up for a median of 6.7 months (IQR, 3.2-19.3 months). Aspirin use decreased slightly from a baseline mean use of 29.4% (95% CI, 28.9%-29.9%) to 27.1% (95% CI, 26.1%-28.0%) during the 24 months before the intervention (P < .001 for slope before and after 24 months before the intervention) with an accelerated decrease after the intervention (mean aspirin use, 15.7%; 95% CI, 14.8%-16.8%; P = .001 for slope before and after intervention). In the primary analysis, the intervention was associated with a significant decrease in major bleeding events per month (preintervention, 0.31%; 95% CI, 0.27%-0.34%; postintervention, 0.21%; 95% CI, 0.14%-0.28%; P = .03 for difference in slope before and after intervention). No change was observed in mean percentage of patients having a thrombotic event from before to after the intervention (0.21% vs 0.24%; P = .34 for difference in slope). In the secondary analysis, reducing aspirin use (starting 24 months before the intervention) was associated with decreases in mean percentage of patients having any bleeding event (2.3% vs 1.5%; P = .02 for change in slope before and after 24 months before the intervention), mean percentage of patients having a major bleeding event (0.31% vs 0.25%; P = .001 for change in slope before and after 24 months before the intervention), and mean percentage of patients with an emergency department visit for bleeding (0.99% vs 0.67%; P = .04 for change in slope before and after 24 months before the intervention), with no change in mean percentage of patients with a thrombotic event (0.20% vs 0.23%; P = .36 for change in slope before and after 24 months before the intervention). Conclusions and Relevance: This quality improvement intervention was associated with an acceleration of a preexisting decrease in aspirin use among patients taking warfarin for atrial fibrillation and/or venous thromboembolism without a clear indication for aspirin therapy. Reductions in aspirin use were associated with reduced bleeding. This study suggests that an anticoagulation clinic-based aspirin deimplementation intervention can improve guideline-concordant aspirin use.