Making decisions about antithrombotic therapy in heart disease. Decision analytic and cost-effectiveness issues

Electronic health record-embedded decision support to reduce stroke risk in patients with atrial fibrillation - Study protocol

BACKGROUND

Atrial fibrillation (AF) is the most common significant cardiac rhythm disorder and is a powerful common risk factor for stroke. Randomized trials have demonstrated that anticoagulation can reduce the risk of stroke in patients with AF. Yet, there continues to be widespread underutilization of this therapy. To address this practice gap locally and improve efforts to reduce the risk of stroke for patients with AF in our health system, we have designed a study to implement and evaluate the effectiveness of an Atrial Fibrillation Decision Support Tool (AFDST) embedded within our electronic health record.

METHODS

Our intervention is provider-facing and focused on decision support. The clinical setting is ambulatory patients being seen by primary care physicians. Patients include those with both incident and prevalent AF. This randomized, prospective trial will enroll 800 patients in our University of Cincinnati Health System who are currently receiving less than optimal anticoagulation therapy as determined by the AFDST. Patients will be randomized to one of two arms - 1) usual care, in which the AFDST is available for use; 2) addition of a best practice advisory (BPA) to the AFDST notifying the clinician that their patient stands to gain a significant benefit from a change in their current thromboprophylactic therapy.

RESULTS

The primary outcome is effectiveness of the BPA measured by change to "appropriate thromboprophylaxis" based on the AFDST recommendation at 3 months post randomization. Secondary endpoints include Reach and Adoption, from the RE-AIM framework for implementation studies. Sample size is based upon an improvement from inappropriate to appropriate anticoagulation therapy estimated at 4% in the usual care arm and ≥10% in the experimental arm.

CONCLUSION

Our goal is to examine whether addition of a BPA to an AFDST focused on primary care physicians in an ambulatory care setting will improve "appropriate thromboprophylaxis" compared with usual care. Results will be examined at 3 months post randomization and at the end of the study to evaluate durability of changes. We expect to complete patient enrollment by the end of June 2022.

TRIAL REGISTRATION

Clinicaltrials.gov NCT04099485.

Evaluation of differences in patient and physician perception of benefit and risks of aspirin and antifibrinolytic therapy in cardiac surgery

It is unclear whether physicians and patients have similar concerns and preferences when considering benefit and risks of aspirin and antifibrinolytic therapy for cardiac surgery. We surveyed both groups to ascertain their perceptions and preferences for treatment in this setting. Both preoperative and postoperative cardiac surgical patients and the physician craft groups caring for them (cardiology, surgery, anaesthesia/critical care), were provided with estimates of benefits and risks of aspirin and antifibrinolytic therapy. All study participants were asked to stipulate the minimal absolute risk reduction required for them to agree to such therapy. When compared with the cardiac surgical patients they treat, physicians required a smaller thrombotic risk reduction with aspirin whilst accepting its known increased risk of bleeding. This was significantly different in a high-risk stroke setting (incidence 5%) where the required relative risk reduction with aspirin use for physicians was 20% versus patients 40% (P <0.001); and for myocardial infarction, physicians 20% versus patients 36% (P=0.051). For antifibrinolytic therapy, the tolerated increased relative risk of stroke for physicians was 20% versus patients 10% (P=0.004), and for myocardial infarction, physicians 16.7% versus patients 4.2% (P <0.001). The three physician craft groups had comparable tolerances of thrombotic risk. Patient and physician preferences for perioperative aspirin and antifibrinolytic therapy sometimes differ based on risk benefit analysis.

Anticoagulation-associated adverse drug events

PURPOSE

Anticoagulant drugs are among the most common medications that cause adverse drug events (ADEs) in hospitalized patients. We performed a 5-year retrospective study at Brigham and Women's Hospital to determine clinical characteristics, types, root causes, and outcomes of anticoagulant-associated ADEs.

METHODS

We reviewed all inpatient anticoagulant-associated ADEs, including adverse drug reactions (ADRs) and medication errors, reported at Brigham and Women's Hospital through the Safety Reporting System from May 2004 to May 2009. We also collected data about the cost associated with hospitalizations in which ADRs occurred.

RESULTS

Of 463 anticoagulant-associated ADEs, 226 were medication errors (48.8%), 141 were ADRs (30.5%), and 96 (20.7%) involved both a medication error and ADR. Seventy percent of anticoagulant-associated ADEs were potentially preventable. Transcription errors (48%) were the most frequent root cause of anticoagulant-associated medication errors, while medication errors (40%) were a common root cause of anticoagulant-associated ADRs. Death within 30 days of anticoagulant-associated ADEs occurred in 11% of patients. After an anticoagulant-associated ADR, most hospitalization expenditures were attributable to nursing costs (mean $33,189 per ADR), followed by pharmacy costs (mean $7451 per ADR).

CONCLUSION

Most anticoagulant-associated ADEs among inpatients result from medication errors and are, therefore, potentially preventable. We observed an elevated 30-day mortality rate among patients who suffered an anticoagulant-associated ADE and high hospitalization costs following ADRs. Further quality improvement efforts to reduce anticoagulant-associated medication errors are warranted to improve patient safety and decrease health care expenditures.

Incremental benefit and cost-effectiveness of high-dose statin therapy in high-risk patients with coronary artery disease

BACKGROUND

Recent clinical trials found that high-dose statin therapy, compared with conventional-dose statin therapy, reduces the risk of cardiovascular events in patients with acute coronary syndromes (ACS) and stable coronary artery disease (CAD). However, the actual benefit and cost-effectiveness of high-dose statin therapy are unknown.

METHODS AND RESULTS

We designed a Markov model to compare daily high-dose with conventional-dose statin therapy for hypothetical 60-year-old cohorts with ACS and stable CAD over patient lifetime. Pooled estimates for major clinical end points (all-cause mortality, myocardial infarction, stroke, rehospitalization, and revascularization) from relevant clinical trials were incorporated. Incremental benefit was quantified as quality-adjusted life-years (QALYs). Threshold analyses determined at what price difference high-dose statins would yield incremental cost-effective ratios below $50,000, $100,000, and $150,000 per QALY gained. In ACS patients, a high-dose versus conventional-dose statin strategy resulted in a gain of 0.35 QALYs. In threshold analyses, a high-dose statin strategy consistently yielded incremental cost-effective ratios below $30,000 per QALY even under conservative model assumptions. In stable CAD patients, a high-dose statin strategy yielded a gain of only 0.10 QALYs and was sensitive to model assumptions about statin efficacy. The daily cost difference between a high- and conventional-dose statin would need to be <$1.70, $2.65, and $3.55 to yield incremental cost-effective ratios below $50,000, $100,000, and $150,000 per QALY.

CONCLUSIONS

High-dose statin therapy is potentially highly effective and cost-effective in patients with ACS. In patients with stable CAD, however, the cost-effectiveness of high-dose statin therapy is highly sensitive to model assumptions about statin efficacy and cost. Use of high-dose statins can be supported on health economic grounds in patients with ACS, but the case is less clear for patients with stable CAD.

Cerebral Sinovenous Thrombosis

Cranial sinovenous disorders comprise a disparate group of illnesses affecting one or more intracranial venous sinuses and cerebral veins, alone or in combination, due to a variety of causes. As medical knowledge advances, fewer and fewer patients have an "idiopathic" diagnosis, with causes clarified in an ever-increasing number of patients. These not only include the long-known puerperal, marantic, infective, and traumatic causes, but in recent years, also a variety of congenital and acquired coagulation disorders, such as protein S, protein C, and antithrombin III deficiency. Certain sinuses are preferentially involved with certain causative entities; for example, cavernous and lateral sinuses are more frequently occluded in relation to infectious processes, either directly or as a parameningeal focus, whereas the superior sagittal sinus is most often occluded by trauma, tumor, or coagulopathy. The optimal treatment of sinovenous occlusion depends on establishing the cause with alacrity, because delays in diagnosis may lead to life-threatening hyperpyrexia, elevations in intracranial pressure, venous infarctions, seizures, coma, and death. However, because up to a third of patients with nonseptic occlusions may survive untreated, with few residua, controversy persists regarding optimal management. There has been a dearth of randomized, prospective treatment trials in this group of disorders. The little data that exist suggest that rapid control of infection, seizure prophylaxis, and anticoagulation must be achieved early so as to prevent progression of thrombosis and intracranial venous hypertension. In recent years, direct retrograde venous thrombolysis has become increasingly available, and has produced such remarkable results that it is likely soon to become the primary treatment of choice for the nontraumatic or nontumoral occlusions.

Risks and benefits of glycoprotein IIb/IIIa antagonists in acute coronary syndrome

BACKGROUND

Recommendations for the use of glycoprotein (GP) IIb/IIIa antagonists should consider not only their effectiveness but also their links with other clinical findings (both favorable and adverse), the risk/benefit ratio in different subgroups of patients, and the existence of other therapeutic alternatives; additionally, the estimates underlying the recommendation should be explicit.

OBJECTIVE

To establish explicit evidence-based recommendations regarding the use of GP IIb/IIIa antagonists in medically treated patients with acute coronary syndrome without ST-segmentelevation.

DATA SOURCES

MEDLINE-based search (1980 to November 1999) of randomized controlled trials for effectiveness data and nonsystematic review of published data regarding utilities of relevant status and clinical events.

STUDY SELECTION

We included clinical trials in which the patients were randomly assigned either to an experimental group treated with intravenous GP IIb/IIIa antagonists or to a control group. We excluded studies in which the intention to perform a percutaneous procedure was a criterion for inclusion.

DATA EXTRACTION

The effectiveness of the treatment was defined as the incidence of death or a nonfatal infarct at 30 days. The risks of the treatment were estimated using the incidence of moderate to severe hemorrhage.

DATA SYNTHESIS

Meta-analysis of randomized controlled trials in patients with acute coronary syndrome and calculation of the threshold number needed to treat (t-NNT).

RESULTS

Compared with conventional treatment, GP IIb/IIIa antagonists reduce the risk of death or nonfatal infarct at 30 days by approximately 11.7% (number needed to treat [NNT] = 65 for the basal risk of patients included in the studies; 95% CI 40 to 203). However, the use of GP IIb/IIIa antagonists increases the risk of moderate to severe hemorrhage by 32%. In an analysis biased in favor of the use of GP IIb/IIIa antagonists, these risks imply a t-NNT of approximately 150, which overlaps with the confidence interval of the basal NNT. The limits of a 95% confidence interval of the NNT are only lower than the t-NNT in patients with a high risk of death/infarct (at least 5%) and low risk of hemorrhage (less than the weighted basal risk in the trials analyzed).

CONCLUSIONS

At present, there is no conclusive evidence that the expected benefits outweigh the nsks in the average patient included in the available trials. The benefit is probably greater than the risks in patients with a high risk of death/infarct and low risk of hemorrhage. In patients with a low risk of death/infarct and/or high risk of hemorrhage, the risks seem to outweigh the benefits and so, in the latter case, such therapy should not be used.

Potential clinical efficacy and cost benefit of a transesophageal echocardiography-guided low-molecular-weight heparin (enoxaparin) approach to antithrombotic therapy in patients undergoing immediate cardioversion from atrial fibrillation

An alternative clinical management strategy and cost analysis model is presented for patients with atrial fibrillation of >2 days' duration who may benefit from immediate cardioversion with self-administered low-molecular-weight heparin (enoxaparin) as a bridge antithrombotic therapy to warfarin, after a negative transesophageal echo-cardiography (TEE) screening for thrombus. Assuming no difference in stroke or bleeding rates, our cost minimization model shows that the TEE-guided enoxaparin treatment costs are $1353 lower per patient than an intravenous unfractionated heparin approach. Sensitivity analyses for stroke and bleeding reveal that the treatment-cost economic dominance of the TEE-guided enoxaparin approach may be enhanced by an expected improvement in clinical outcome.

Decision analysis and guidelines for anticoagulant therapy to prevent stroke in patients with atrial fibrillation

BACKGROUND

Clinical guidelines are needed on whether or not to use anticoagulant therapy to prevent stroke in patients with non-valvular atrial fibrillation. We did a Markov decision analysis to model decision-making with regard to warfarin treatment in patients with atrial fibrillation, and used the model to develop evaluative guidelines.

METHODS

The decision analysis involved a systematic literature review supplemented by patients' estimates of the quality of life associated with different states of health, secondary analysis of stroke-registry data, and estimation of service costs; it also incorporated a sensitivity analysis. The derived guidelines were subsequently applied to a cohort of patients with atrial fibrillation.

FINDINGS

We constructed decision tables for 12 age and sex groups. For most risk combinations, warfarin treatment would have decreased health-care costs and increased quality-of-life years, although the clinical decision was sensitive to patients' preferences and to the estimate of warfarin's effectiveness. 97% of women with atrial fibrillation older than 75 years, and 69% aged 65-74 would have been recommended for treatment; for men, the corresponding figures would have been 75% and 53%. With the upper quartile for the loss of quality of life associated with being on warfarin treatment (1.00), all but two of the 116 patients without contraindications would have been treated, whereas with the lower quartile (0.92), only 27 of 116 would have been treated.

INTERPRETATION

Decision analysis is useful in the incorporation of complex probabilistic data into informed decision-making, the identification of factors influencing such decisions, and the subsequent development of evaluative guidelines.

Cost-effectiveness of preference-based antithrombotic therapy for patients with nonvalvular atrial fibrillation

BACKGROUND AND PURPOSE

Recent atrial fibrillation guidelines recommend the incorporation of patient preferences into the selection of antithrombotic therapy. However, no trial has examined how incorporating such preferences would affect quality-adjusted survival or medical expenditure. We compared 10-year projections of quality-adjusted survival and medical expenditure associated with two atrial fibrillation treatment strategies: warfarin-for-all therapy versus preference-based therapy. The preference-based strategy prescribed whichever antithrombotic therapy, warfarin or aspirin, had the greater projected quality-adjusted survival.

METHODS

We used decision analysis stratified by the number of stroke risk factors (history of stroke, transient ischemic attack, hypertension, diabetes, or heart disease). The base case focused on compliant 65-year-old patients who had nonvalvular atrial fibrillation and no contraindications to antithrombotic therapy.

RESULTS

In patients whose only risk factor for stroke was atrial fibrillation, preference-based therapy improved projected quality-adjusted survival by 0.05 quality-adjusted life year (QALY) and saved $670. For patients who had atrial fibrillation and one additional risk factor for stroke, preference-based therapy improved quality-adjusted survival by 0.02 QALY and saved $90. In patients who had atrial fibrillation and multiple additional risk factors for stroke, preference-based therapy increased medical expenditures and did not improve quality-adjusted survival substantially. The benefits of preference-flexible therapy arose from the minority of patients who would have had a longer quality-adjusted survival if they had been prescribed aspirin rather than warfarin.

CONCLUSIONS

As do risks of stroke and of hemorrhage, patients' preferences help to determine which antithrombotic therapy is optimal. Preference-based treatment should improve quality-adjusted survival and reduce medical expenditure in patients who have nonvalvular atrial fibrillation and not more than one additional risk factor for stroke.

Preventing stroke recurrence in patients with patent foramen ovale: antithrombotic therapy, foramen closure, or therapeutic abstention? A decision analytic perspective

Emphasis on the role of patent foramen ovale as a potential risk factor for ischemic paradoxical stroke has recently increased. Current therapeutic options for secondary stroke prevention include long-term antithrombotic therapies and invasive closure of the defect, but selective indications have not been evaluated. Therefore we developed a Markov-based decision analysis model for a hypothetical cohort of patients 55 years of age with presumed paradoxical embolism, measuring for each therapy the risks of stroke recurrence, treatment-related complications, and death after 5 years and the quality-adjusted life-years. Over a wide range of stroke risk recurrence (0.8% per year to 7% per year), the gain provided by closure of the defect exceeded the one obtained by other therapeutic options. When the risk exceeded 0.8% per year and 1.4% per year, respectively, this was also verified for anticoagulation and antiplatelet therapies compared with therapeutic abstention. Therapeutic abstention was the preferred strategy under 0.8% per year. Sensitivity analyses identified key parameters influencing the choice of therapy. These included estimates of stroke recurrence, bleeding rates, surgery-related case fatality rates, and age. Considering the risks of treatment and the devastating consequences of a recurrent stroke, our model suggests that if the estimated risk of paradoxical stroke recurrence is > 0.8% per year, therapeutic abstention becomes the worst option. Above this threshold secondary stroke prevention with anticoagulation therapy or surgical closure of the defect is the preferred strategy, and assessment of both the risk of stroke recurrence and the risk related to therapeutic options should guide individual therapeutic decision making.

Anticoagulation Management as a Risk Factor for Adverse Events: Grounds for Improvement

Oral anticoagulation therapy has a high risk/benefit profile because of its narrow therapeutic index and the influence of concomitant patient characteristics. The manner in which oral anticoagulation is managed is seldom mentioned as a risk factor for adverse events, but recent studies identify it as such. There are two general models of anticoagulation management, characterized as routine medical care and coordinated care. The literature suggests a rate of major hemorrhage of approximately 10% under the former model, compared with approximately 3.5% under the latter model. Similar, if not greater, differences, are seen for the rate of thrombotic events ( approximately 12% vs. 3.5%). Because of fewer adverse events, coordinated care results in cost savings due to reduced hospitalizations and emergency room visits. If the full benefit of anticoagulation is to be gained, there is a strong rationale for the development and promotion of anticoagulation management services.

Primary stroke prevention in nonvalvular atrial fibrillation: implementing the clinical trial findings

OBJECTIVE

To review the clinical trials evaluating warfarin for primary stroke prophylaxis in nonvalvular atrial fibrillation (NVAF), to discuss the relative benefits and risks of warfarin versus aspirin therapy, and to review the clinical practice guidelines and identify potential barriers to their implementation in clinical practice.

DATA SOURCES

A MEDLINE literature search was performed to identify clinical trials of antithrombotic therapy for NVAF, clinical practice guidelines, studies evaluating physician practices and attitudes, cost-effectiveness studies, and pertinent review articles. Key search terms included atrial fibrillation, stroke, antithrombotic, warfarin, aspirin, and cost-effectiveness.

DATA EXTRACTION

Prospective, randomized clinical trials were selected for analysis. Clinical practice guidelines from recognized panels of experts were reviewed. Comprehensive review articles were selected.

DATA SYNTHESIS

NVAF is a common arrhythmia that is associated with a substantial risk for stroke. Seven prospective, randomized, clinical trials have conclusively demonstrated the efficacy of warfarin for stroke prevention. The greatest benefits are achieved in older patients and those with comorbidities that increase their risk for stroke. The potential benefits of preventing a devastating stroke, however, must be weighed against the potential for bleeding complications. Warfarin has been shown to be cost-effective in high-risk patients, provided the rate of complications is minimized. Nonetheless, many physicians remain hesitant to implement warfarin therapy in older, high-risk patients. The clinical data on aspirin are less consistent than those observed with warfarin. Aspirin appears to be most effective in younger individuals or those considered to be at low risk for stroke.

CONCLUSIONS

In patients with NVAF, the personal, social, and economic consequences of stroke are often devastating. Clinical trials have provided definitive proof that the risks of stroke can be significantly reduced through the use of appropriate antithrombotic therapy. Despite this evidence and the recommendations of a number of clinical practice guidelines, variations in care exist that continue to place patients at risk. Additional outcomes research is needed to evaluate the impact of the clinical trial findings and practice guidelines on clinical practice and to develop methods for overcoming barriers to implementation.