Adverse events in low versus normal body weight patients prescribed apixaban for atrial fibrillation.

Safety and efficacy of direct oral anticoagulants (DOAC) in low weight patients with atrial fibrillation (AF) is unclear due to few low body weight patients enrolled in clinical trials. To assess bleeding and thrombotic event rates for patients with AF that are prescribed apixaban and have a low versus normal body weight. We analyzed patients with AF prescribed apixaban from 2017 to 2020 with at least 12 months of follow-up. Patients were divided into low [< 60 kg (kg)] and normal (60-100 kg) weight cohorts. Bleeding and thrombotic event rates were compared. Poisson regression and Cox proportional hazard models were used to estimate adjusted adverse event rates. A total of 545 patients met inclusion criteria. In the unadjusted analysis, there was an increase in non-major bleeding events requiring an Emergency Department visit more often in the low versus normal weight cohort (10.8 versus 7.4 per 100 patient-years, p = 0.15). Thrombotic event rates also occurred more often in the lower versus normal weight cohort (2.4 versus 0.9 per 100 patient-years, p = 0.09). However, adjusted analysis found no statistically significant difference in bleeding or thrombotic events between low and normal weight cohorts. The adjusted hazard ratio for bleeding was similar between the two weight cohorts. The use of apixaban in low body weight patients was not associated with higher rates of bleeding or thrombotic events, compared to those with normal body weight, after adjusting for potential confounding covariates. Larger studies may offer further insight into the overall safety and efficacy of DOAC therapy in these patients.

Higher OAK (Oral Anticoagulation Knowledge) score at baseline associated with better TTR (Time in Therapeutic Range) in patients taking warfarin.

A lack in patient knowledge of warfarin therapy is associated with poor adherence. This knowledge gap may result in a lower INR Time in Therapeutic Range (TTR). To investigate association between patient anticoagulation knowledge and warfarin control. Michigan Anticoagulation Quality Improvement Initiative (MAQI2) is a Blue Cross Blue Shield of Michigan sponsored consortium of six anticoagulation management services. Patients prescribed warfarin at two MAQI2 sites completed a voluntary Oral Anticoagulation Knowledge (OAK) questionnaire at warfarin initiation and 6-month follow-up. The results of 20 OAK questions and TTRs (excluding 1st month post-initiation) were compared using chi-square tests, t-tests and multivariate analysis adjusting for SAMe-TT2R2 and days on warfarin. Of 1836 surveys distributed at warfarin initiation, 481 (26.2%) patients completed the baseline questionnaire (within 1 month post-initiation): mean OAK score: 14.6 ± 3.4. Of those, 147 (30.6%) completed 6-month follow-up surveys (OAK: 12.7 ± 5.8). Patients with TTR ≥ 70% at baseline scored higher on OAK tests than patients with TTR < 70% in unadjusted analyses (15.1 ± 3.2 v. 14.2 ± 3.5, p = 0.003) and adjusted analysis (p = 0.020). There was no unadjusted or adjusted difference in OAK scores at 6-month follow-up between patients with TTR ≥ 70% and TTR < 70%. For patients who completed baseline and follow-up surveys, there was a decrease of 2.4 points in OAK score between baseline and 6-month follow up (p < 0.001). Higher baseline, but not follow-up, OAK score is associated with better warfarin control and average OAK scores decreased between baseline and follow-up. Further studies are needed to determine what type of patient education may improve patient knowledge retention and warfarin control.

Adverse events in patients taking apixaban or rivaroxaban who have undergone bariatric surgery: a retrospective case series.

Clinical trials comparing direct oral anticoagulants (DOAC) to warfarin excluded patients with a history of bariatric surgery. The anatomic changes from bariatric procedures have several effects on drug absorption which can have serious consequences for these patients. We sought to describe real-world use of DOACs among adults that had a history of bariatric surgery or underwent a bariatric surgery while receiving a DOAC. We conducted a retrospective case series of adult patients, at a large academic medical center, who initiated any DOAC in 2016 thru 2019 and had a history of bariatric surgery or underwent a bariatric surgery while receiving a DOAC. Thrombotic and bleeding events were described using summary statistics and bleeding severity was described using the International Society on Thrombosis and Haemostasis criteria. Twenty-eight patients met the inclusion criteria of having bariatric surgery (Roux-en-Y gastric bypass, sleeve gastrectomy or gastric band) and receiving a DOAC. Twenty (71.4%) were prescribed apixaban and eight (28.6%) were prescribed rivaroxaban. Seven patients (25%) experienced at least one clinically relevant non-major bleeding event, including one patient (3.6%) that had a major bleeding event. Two patients (7.1%) had a thromboembolic event. Coagulation laboratory studies were infrequently performed at the time of the bleeding or clotting events. Among patients with a history of bariatric surgery, use of DOACs were commonly associated with clinically relevant non-major bleeding events and less commonly associated with major bleeding and thromboembolic events. Larger studies may offer further insight into the overall safety and efficacy of DOAC therapy in patients that have undergone bariatric surgery. The specific role of coagulation laboratory studies warrants further evaluation.

Mind the gap: results of a multispecialty survey on coordination of care for peri-procedural anticoagulation.

To understand how physicians from various specialties perceive coordination of care when managing peri-procedural anticoagulation. Cross-sectional survey of cardiologists, gastroenterologists, and primary care physicians (PCPs) in an integrated health system (N = 251). The survey began with a vignette of a patient with atrial fibrillation co-managed by his PCP, cardiologist, and an anticoagulation clinic who must hold warfarin for a colonoscopy. Respondents' experiences and opinions around responsibilities and institutional support for managing peri-procedural anticoagulation were elicited using multiple choice questions. We examined differences in responses across specialties using Chi square analysis. The response rate was 51% (n = 127). 52% were PCPs, 28% cardiologists, and 21% gastroenterologists. Nearly half (47.2%) of respondents believed that the cardiologist should be primarily responsible for managing peri-procedural anticoagulation, while fewer identified the PCP (25.2%), anticoagulation clinic (21.3%), or gastroenterologist (6.3%; p = 0.09). Respondents across specialties had significantly different approaches to deciding how to manage the clinical case presented (p < 0.001). Most cardiologists (60.0%) would decide whether to offer bridging without consulting with other providers or clinical resources, while most PCPs would decide after consulting clinical resources (57.6%). Gastroenterologists would most often (46.2%) defer the decision to another provider. A majority of all three specialties agreed that their institution could do more to help manage peri-procedural anticoagulation, and there was broad support (88.1%) for anticoagulation clinics' managing all aspects of peri-procedural anticoagulation. Providers across specialties agree that their institution could do more to help manage peri-procedural anticoagulation, and overwhelmingly support anticoagulation clinics' taking responsibility.

Warfarin for prevention of thromboembolism in atrial fibrillation: comparison of patient characteristics and outcomes of the "Real-World" Michigan Anticoagulation Quality Improvement Initiative (MAQI2) registry to the RE-LY, ROCKET-AF, and ARISTOTLE trials.

Randomized controlled trials (RCTs) examining warfarin use for stroke prevention in atrial fibrillation (AF) may not accurately reflect real-world populations. We aimed to determine the representativeness of the RCT populations to real-world patients and to describe differences in the characteristics of trial populations from trial eligible patients in a real-world setting. We hypothesized that a significant fraction of real-world patients would not qualify for the RE-LY, ROCKET-AF, and ARISTOTLE trials and that real-world patients qualifying for the studies may have more strokes and bleeding events. We compared the inclusion and exclusion criteria, patient characteristics, and clinical outcomes from RE-LY, ROCKET-AF, and ARISTOTLE against data from the Michigan Anticoagulation Quality Improvement Initiative (MAQI2), a regional network of six community- and academic-based anticoagulation clinics. Of the 1446 non-valvular AF patients in the MAQI2 registry taking warfarin, approximately 40-60% would meet the selection criteria used in RE-LY (788, 54.5%), ROCKET-AF (566, 39.1%), and ARISTOTLE (866, 59.9%). The most common reasons for exclusion from one or more trial were anemia (15.1%), other concurrent medications (11.2%), and chronic kidney disease (9.4%). Trial-eligible MAQI2 patients were older, more frequently female, with a higher rate of paroxysmal AF, and lower rates of congestive heart failure, previous stroke, and previous myocardial infarction than the trial populations. MAQI2 patients eligible for each trial had a lower rate of stroke and similar rate of major bleeding than was observed in the trials. A sizable proportion of real-world AF patients managed in anticoagulation clinics would not have been eligible for the RE-LY, ROCKET-AF, and ARISOTLE trials. The expected stroke risk reduction and bleeding risk among real-world AF patients on warfarin may not be congruent with published clinical trial data.

SAMe-TT2R2 predicts quality of anticoagulation in patients with acute venous thromboembolism: The MAQI2 experience.

A high SAMe-TT2R2 score predicted poor warfarin control and adverse events among atrial fibrillation patients. However, the SAMe-TT2R2 score has not been well validated in venous thromboembolism (VTE) patients. A cohort of 1943 warfarin-treated patients with acute VTE was analyzed to correlate the SAMe-TT2R2 score with time in therapeutic range (TTR) and clinical adverse events. A TTR <60% was more frequent among patients with a high (>2) versus low (0-1) SAMe-TT2R2 score (63.4% vs 52.3%, p<0.0001). A high SAMe-TT2R2 score (>2) correlated with increased overall adverse events (7.9 vs 4.5 overall adverse events/100 patient years, p=0.002), driven primarily by increased recurrent VTE rates (4.2 vs 1.5 recurrent VTE/100 patient years, p=0.0003). The SAMe-TT2R2 score had a modest predictive ability for international normalized ratio (INR) quality and adverse clinical events among warfarin-treated VTE patients. The utility of the SAMe-TT2R2 score to guide clinical decision-making remains to be investigated.

Prescribing trends of atrial fibrillation patients who switched from warfarin to a direct oral anticoagulant.

Direct oral anticoagulant (DOAC) agents offer several lifestyle and therapeutic advantages for patients relative to warfarin in the treatment of atrial fibrillation (AF). These alternative agents are increasingly used in the treatment of AF, however the adoption practices, patient profiles, and reasons for switching to a DOAC from warfarin have not been well studied. Through the Michigan Anticoagulation Quality Improvement Initiative, abstracted data from 3873 AF patients, enrolled between 2010 and 2015, were collected on demographics and comorbid conditions, stroke and bleeding risk scores, and reasons for anticoagulant switching. Over the study period, patients who switched from warfarin to a DOAC had similar baseline characteristics, risk scores, and insurance status but differed in baseline CrCl. The most common reasons for switching were patient related ease of use concerns (37.5%) as opposed to clinical reasons (16.5% of patients). Only 13% of patients that switched to a DOAC switched back to warfarin by the end of the study period.

Root Cause Analysis of Adverse Events in an Outpatient Anticoagulation Management Consortium.

BACKGROUND: A number of factors can lead to adverse events (AEs) in patients taking warfarin. Performing a root cause analysis (RCA) of serious AEs is one systematic way of determining the causes of these events. METHODS: Multidisciplinary teams were formed at Michigan Anticoagulation Quality Improvement Initiative (MAQI2) sites with organized anticoagulation management services (AMS). Medical records from patients who suffered serious AEs (major bleed, embolic stroke, venous thromboembolism) were reviewed, and AMS staff were interviewed to determine the root cause using the "5 Whys" technique. More than 600 patients had an AE and underwent screening by trained RNs. Of these, 79 required full review by a multidisciplinary panel. All potential contributing factors (comorbidities, concurrent medications, current protocols) were assessed to determine the main factor that caused the AE. RESULTS: Full RCA was completed in 79 cases. The main contributing factor was identified in 69/79 (87%) cases. Most identified AEs, 55/69 (80%), were due to patient-specific factors such as comorbidities. Patient-to-provider and provider-to-provider communication accounted for 16/69 (23%) of events and was the second most common cause. Other causes included protocol non-adherence and technology/equipment issues. After each detailed review, the multidisciplinary panel recommended system changes that addressed the primary cause. CONCLUSION: The majority of severe AEs for patients taking warfarin were related to nonmodifiable patient-related issues. The remaining AEs were primarily due to patient-to-provider and provider-to-provider communication issues. Methods for improving communication need to be addressed, and methods for more effective patient education should be investigated.

Renal function in atrial fibrillation patients switched from warfarin to a direct oral anticoagulant.

All available direct oral anticoagulants (DOACs) are at least partially eliminated by the kidneys. These agents are increasingly being used as alternatives to warfarin for stroke prevention in patients with atrial fibrillation. The aim of this study was to identify changes in renal function and associated DOAC dosing implications in a multicenter cohort of atrial fibrillation patients switched from warfarin to DOAC treatment. We included all patients in the Michigan Anticoagulation Quality Improvement Initiative cohort who switched from warfarin to a DOAC with atrial fibrillation as their anticoagulant indication between 2009 and 2014, and who had at least two creatinine values. Compliance with FDA-recommended dosing based on renal function was assessed. Of the 189 patients switched from warfarin to a DOAC, 34 (18.0 %) had a baseline creatinine clearance <50 mL/min and 23 (12.2 %) experienced important fluctuations in renal function. Of these 23 patients, 6 (26.1 %) should have impacted the DOAC dosing, but only 1 patient actually received an appropriate dose adjustment. Additionally, 15 (7.9 %) of patients on DOACs had a dose change performed, but only one patient demonstrated a change in renal function to justify the dose adjustment. Most atrial fibrillation patients who switched from warfarin to a DOAC had stable renal function. However, the majority of patients who had a change in renal function did not receive the indicated dose change. As the use of DOACs expands, monitoring of renal function and appropriate dose adjustments are critical.

The changing characteristics of atrial fibrillation patients treated with warfarin.

It has been suggested that direct oral anticoagulants are being preferentially used in low risk atrial fibrillation (AF) patients. Understanding the changing risk profile of new AF patients treated with warfarin is important for interpreting the quality of warfarin delivery through an anticoagulation clinic. Six anticoagulation clinics participating in the Michigan Anticoagulation Quality Improvement Initiative enrolled 1293 AF patients between 2010 and 2014 as an inception cohort. Abstracted data included demographics, comorbidities, medication use and all INR values. Risk scores including CHADS2, CHA2DS2-VASc, HAS-BLED, SAMe-TT2R2, and Charlson comorbidity index (CCI) were calculated for each patient at the time of warfarin initiation. The quality of anticoagulation was assessed using the Rosendaal time in the therapeutic range (TTR) during the first 6 months of treatment. Between 2010 and 2014, patients initiating warfarin therapy for AF had an increasing mean CHADS2 (2.0 ± 1.1 to 2.2 ± 1.4, p = 0.02) and CCI (4.7 ± 1.8 to 5.1 ± 2.0, p = 0.03), and a trend towards increasing mean CHA2DS2-VASc, HAS-BLED, and SAMe-TT2R2 scores. The actual TTR remained unchanged over the study period (62.6 ± 18.2 to 62.7 ± 17.0, p = 0.98), and the number of INR checks did not change (18.9 ± 5.2 to 18.5 ± 5.1, p = 0.06). Between 2010 and 2014, AF patients newly starting warfarin had mild increases in risk for stroke and death with sustained quality of warfarin therapy.

Warfarin use in atrial fibrillation patients at low risk for stroke: analysis of the Michigan Anticoagulation Quality Improvement Initiative (MAQI(2)).

To more accurately quantify the proportion of anticoagulated patients with atrial fibrillation (AF) that may be inappropriately treated with warfarin for stroke prevention. Patients with AF have an increased risk of stroke, which is lowered by the use of warfarin. However there is likely more potential harm than benefit in patients that do not have additional stroke risk factors. Studies have described overuse of warfarin for stroke prophylaxis in lowest risk patients. However, many of those studies did not assess for electrical cardioversion (ECV) or radiofrequency ablation (RFA) as indications for warfarin therapy. Data from 1852 non-valvular AF patients treated with warfarin between October 2009 and October 2011 at seven anticoagulation centers participating in the Michigan Anticoagulation Quality Improvement Initiative registry were analyzed. Low risk AF patients were risk stratified using the CHADS2 scoring systems, with a score of zero representing lowest risk. 193 (10.4 %) of AF patients receiving warfarin were identified as having the lowest risk of stroke by the CHADS2 score. Of the patients with CHADS2 = 0, 130 (67.4 %) had undergone a recent ECV and/or RFA. Of all AF patients, only 63 (3.4 %) had a CHADS2 score of 0 and no recent ECV or RFA. The vast majority of AF patients receiving anticoagulation in this multi-center registry are doing so in accordance with national and international guidelines. In contrast to prior population-based studies, very few low risk patients are receiving inappropriate warfarin therapy for stroke prophylaxis in AF, when procedure-based indications are also considered.

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.

Use of warfarin for venous thromboembolism prophylaxis following knee and hip arthroplasty: results of the Michigan Anticoagulation Quality Improvement Initiative (MAQI2).

Total knee arthroplasty (TKA) and total hip arthroplasty (THA) are associated with high rates of venous thromboembolism (VTE). Anticoagulants, such as warfarin, are commonly used to prevent VTE in such patients. The practice and effectiveness of warfarin in real world populations is not well documented. 595 TKA and THA patients treated with warfarin were followed by two anticoagulation clinics in the Michigan Anticoagulation Quality Improvement Initiative. Length of prescribed anticoagulation, percent time in therapeutic range (%TTR) and time to first therapeutic INR were calculated for each surgical group. For THA, all 300 patients received at least ten days with a 28-day median length of anticoagulation therapy. For TKA, all 295 patients received at least 10 days with a 28-day median length of anticoagulation therapy. For THA patients, time to first therapeutic INR was on average 12.0 ± 8.0 days with a mean %TTR of 36.6 ± 26.8% for goal INR 2.0-3.0. For THA patients, 39 (13%) never reached target INR. For TKA patients, time to first therapeutic INR was on average 12.8 ± 10.3 days with a mean %TTR of 36.0 ± 28.3% for goal INR 2.0-3.0. For TKA patients, 44 (14.9%) never reached target INR. Many orthopaedic surgeons who use warfarin for post-arthroplasty VTE prophylaxis do so in accordance with national guidelines. The time to first therapeutic INR is strikingly long and %TTR markedly low for these patients, raising questions about the efficacy of warfarin therapy in the first 1-2 post-operative weeks. Further studies to investigate the best target INR for warfarin prophylaxis, as well as the composite rates of VTE and clinically relevant bleeding from treatment with warfarin, LMWH and newer anticoagulants are needed.

Anticoagulation Changes Following Major and Clinically Relevant Nonmajor Bleeding Events in Non-valvular Atrial Fibrillation Patients.

Background: Bleeding events are common complications of oral anticoagulant drugs, including both warfarin and the direct oral anticoagulants (DOACs). Some patients have their anticoagulant changed or discontinued after experiencing a bleeding event, while others continue the same treatment. Differences in anticoagulation management between warfarin- and DOAC-treated patients following a bleeding event are unknown. Methods: Patients with non-valvular atrial fibrillation from six anticoagulation clinics taking warfarin or DOAC therapy who experienced an International Society of Thrombosis and Haemostasis (ISTH)-defined major or clinically relevant non-major (CRNM) bleeding event were identified between 2016 and 2020. The primary outcome was management of the anticoagulant following bleeding (discontinuation, change in drug class, and restarting of same drug class). DOAC- and warfarin-treated patients were propensity matched based on the individual elements of the CHA2DS2-VASc and HAS-BLED scores as well as the severity of the bleeding event. Results: Of the 509 patients on warfarin therapy and 246 on DOAC therapy who experienced a major or CRNM bleeding event, the majority of patients continued anticoagulation therapy. The majority of warfarin (231, 62.6%) and DOAC patients (201, 81.7%) restarted their previous anticoagulation. Conclusion: Following a bleeding event, most patients restarted anticoagulation therapy, most often with the same type of anticoagulant that they previously had been taking.

Outcomes in patients undergoing periprocedural interruption of warfarin or direct oral anticoagulants.

BACKGROUND: Differences in clinical outcomes following a temporary interruption of warfarin or a direct oral anticoagulant (DOAC) for a surgical procedure are not well described. Differences in patient characteristics from practice-based cohorts have not typically been accounted for in prior analyses. AIM: To describe risk-adjusted differences in postoperative outcomes following an interruption of warfarin vs DOACs. METHODS: Patients receiving care at six anticoagulation clinics participating in the Michigan Anticoagulation Quality Improvement Initiative were included if they had at least one oral anticoagulant interruption for a procedure. Inverse probability of treatment weighting (IPTW) was used to balance baseline differences between the warfarin cohort and DOAC cohort. Bleeding and thromboembolic events within 30 days following the procedure were compared between the IPTW cohorts using the Poisson distribution test. RESULTS: A total of 525 DOAC patients were matched with 1323 warfarin patients, of which 923 were nonbridged warfarin patients and 400 were bridged warfarin patients. The occurrence of postoperative minor bleeding (10.8% vs. 4.7%, p < .001), major bleeding (2.9% vs. 1.1%, p = .01) and clinically relevant nonmajor bleeding (CRNMB) (6.5% vs. 3.0%, p = .002) was greater in the DOAC cohort compared with the nonbridged warfarin cohort. The rates of postoperative bleeding outcomes were similar between the DOAC and the bridged warfarin cohorts. CONCLUSION: Perioperative interruption of DOACs, compared with warfarin without bridging, is associated with a higher incidence of 30-day minor bleeds, major bleeds, and CRNMBs. Further research investigating the perioperative outcomes of these two classes of anticoagulants is warranted.

Management strategies following slightly out-of-range INRs: watchful waiting vs dose changes.

Patients' international normalized ratios (INRs) often fall slightly out of range. In these cases, the American College of Chest Physicians (ACCP) guidelines suggest maintaining the current warfarin dose and retesting the INR within the following 2 weeks (watchful waiting). We sought to determine whether watchful waiting or dose changes for slightly out-of-range INRs is more effective in obtaining in-range INRs at follow-up. INRs and management strategies of warfarin-treated patients within the Michigan Anticoagulation Quality Improvement Initiative registry were analyzed. Management strategies included watchful waiting or dose changes. INRs slightly out of range (target range 2.0-3.0) and their associated management were identified. Multilevel mixed-effects logistic regression was used to estimate the probability of the next INR being in range, adjusted for clustering due to multiple out-of-range INRs per patient. A total of 45 351 slightly out-of-range INRs (ranging 1.50-1.99 and 3.01-3.49) from 8288 patients were identified. The next INR was slightly less likely to be in range with watchful waiting than with a dose change (predicted probabilities 58.9% vs 60.0%, P = 0.024). Although a significant statistical difference was detected in the probabilities of the next INR being back in range when managed by a dose change compared with watchful waiting following a slightly out-of-range INR, the magnitude of the difference was small and unlikely to represent clinical importance. Our study supports the current guideline recommendations for watchful waiting in cases of slightly out-of-range INRs values.

Length of Anticoagulation in Provoked Venous Thromboembolism: A Multicenter Study of How Real-World Practice Mirrors Guideline Recommendations.

Background For more than a decade, guidelines have recommended a limited 3 months of anticoagulation for the treatment of provoked venous thromboembolism (VTE). How closely real-world practice follows guideline recommendations is not well described. Methods and Results In our multicenter, retrospective cohort study, we evaluated trends in anticoagulation duration for patients enrolled in the MAQI2 (Michigan Anticoagulation Quality Improvement Initiative) registry who were receiving anticoagulation for a provoked VTE. The MAQI2 registry comprises 6 centers in Michigan that manage patients' long-term anticoagulation. We identified 474 patients on warfarin and 302 patients on direct oral anticoagulants who were receiving anticoagulation for a primary indication of provoked VTE between 2008 and 2020. Using a predefined threshold of 120 days (3 months plus a buffer period), predictors of extended anticoagulant use were identified using multivariable logistic regression. Most patients received >120 days of anticoagulation, regardless of which medication was used. The median (25th-75th percentile) length of treatment for patients taking warfarin was 142 (91-234) days and for direct oral anticoagulants was 180 (101-360) days. Recurrent VTE (odds ratio [OR], 2.75 [95% CI, 1.67-4.53]), history of myocardial infarction (OR, 3.92 [95% CI, 1.32-11.7]), and direct oral anticoagulant rather than warfarin use (OR, 2.22 [95% CI, 1.59-3.08]) were independently associated with prolonged anticoagulation. Conclusions In our cohort of patients with provoked VTE, most patients received anticoagulation for longer than the guideline-recommended 3 months. This demonstrates a potential opportunity to improve care delivery and reduce anticoagulant-associated bleeding risk.

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.