Dataset Information

Can We Predict Individual Combined Benefit and Harm of Therapy? Warfarin Therapy for Atrial Fibrillation as a Test Case.

ABSTRACT:

Objectives

To construct and validate a prediction model for individual combined benefit and harm outcomes (stroke with no major bleeding, major bleeding with no stroke, neither event, or both) in patients with atrial fibrillation (AF) with and without warfarin therapy.

Methods

Using the Kaiser Permanente Colorado databases, we included patients newly diagnosed with AF between January 1, 2005 and December 31, 2012 for model construction and validation. The primary outcome was a prediction model of composite of stroke or major bleeding using polytomous logistic regression (PLR) modelling. The secondary outcome was a prediction model of all-cause mortality using the Cox regression modelling.

Results

We included 9074 patients with 4537 and 4537 warfarin users and non-users, respectively. In the derivation cohort (n = 4632), there were 136 strokes (2.94%), 280 major bleedings (6.04%) and 1194 deaths (25.78%) occurred. In the prediction models, warfarin use was not significantly associated with risk of stroke, but increased the risk of major bleeding and decreased the risk of death. Both the PLR and Cox models were robust, internally and externally validated, and with acceptable model performances.

Conclusions

In this study, we introduce a new methodology for predicting individual combined benefit and harm outcomes associated with warfarin therapy for patients with AF. Should this approach be validated in other patient populations, it has potential advantages over existing risk stratification approaches as a patient-physician aid for shared decision-making.

SUBMITTER: Li G

PROVIDER: S-EPMC4981352 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Publications

Can We Predict Individual Combined Benefit and Harm of Therapy? Warfarin Therapy for Atrial Fibrillation as a Test Case.

Li Guowei G Thabane Lehana L Delate Thomas T Witt Daniel M DM Levine Mitchell A H MA Cheng Ji J Holbrook Anne A

PloS one 20160811 8

<h4>Objectives</h4>To construct and validate a prediction model for individual combined benefit and harm outcomes (stroke with no major bleeding, major bleeding with no stroke, neither event, or both) in patients with atrial fibrillation (AF) with and without warfarin therapy.<h4>Methods</h4>Using the Kaiser Permanente Colorado databases, we included patients newly diagnosed with AF between January 1, 2005 and December 31, 2012 for model construction and validation. The primary outcome was a pre ...[more]

PMID: 27513986

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Project description:BackgroundGuidelines recommend warfarin use in patients with atrial fibrillation solely on the basis of risk for ischemic stroke without antithrombotic therapy. These guidelines rely on ischemic stroke rates observed in older trials and do not explicitly account for increased risk for hemorrhage.ObjectiveTo quantify the net clinical benefit of warfarin therapy in a cohort of patients with atrial fibrillation.DesignMixed retrospective and prospective cohort study of patients with atrial fibrillation between 1996 and 2003.SettingAn integrated health care delivery system.Patients13 559 adults with nonvalvular atrial fibrillation.MeasurementsWarfarin exposure, patient characteristics, CHADS(2) score (1 point for each of congestive heart failure, hypertension, age, and diabetes and 2 points for stroke), and outcome events were ascertained from health plan records and databases. Net clinical benefit was defined as the annual rate of ischemic strokes and systemic emboli prevented by warfarin minus intracranial hemorrhages attributable to warfarin, multiplied by an impact weight. The base-case impact weight was 1.5, reflecting the greater clinical impact of intracranial hemorrhage versus thromboembolism.ResultsPatients accumulated more than 66 000 person-years of follow-up. The adjusted net clinical benefit of warfarin for the cohort overall was 0.68% per year (95% CI, 0.34% to 0.87%). Adjusted net clinical benefit was greatest for patients with a history of ischemic stroke (2.48% per year [CI, 0.75% to 4.22%]) and for those 85 years or older (2.34% per year [CI, 1.29% to 3.30%]). The net clinical benefit of warfarin increased from essentially zero in CHADS(2) stroke risk categories 0 and 1 to 2.22% per year (CI, 0.58% to 3.75%) in CHADS(2) categories 4 to 6. The patterns of results were preserved when weighting factors for intracranial hemorrhage of 1.0 and 2.0 were used.LimitationsResidual confounding is a possibility. Some outcome events were probably missed by the screening algorithm or when medical records were unavailable.ConclusionExpected net clinical benefit of warfarin therapy is highest among patients with the highest untreated risk for stroke, which includes the oldest age category. Risk assessment that incorporates both risk for thromboembolism and risk for intracranial hemorrhage provides a more quantitatively informed basis for the decision on antithrombotic therapy in patients with atrial fibrillation.Primary funding sourceNational Institute on Aging; National Heart, Lung, and Blood Institute; and Massachusetts General Hospital.

Project description:ObjectivesTo determine the incremental net health benefits of dabigatran etexilate 110 mg and 150 mg twice daily and warfarin in patients with non-valvular atrial fibrillation and to estimate the cost effectiveness of dabigatran in the United Kingdom.DesignQuantitative benefit-harm and economic analyses using a discrete event simulation model to extrapolate the findings of the RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy) study to a lifetime horizon.SettingUK National Health Service. Population Cohorts of 50,000 simulated patients at moderate to high risk of stroke with a mean baseline CHADS(2) (Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes mellitus, previous Stroke/transient ischaemic attack) score of 2.1.Main outcome measuresQuality adjusted life years (QALYs) gained and incremental cost per QALY of dabigatran compared with warfarin.ResultsCompared with warfarin, low dose and high dose dabigatran were associated with positive incremental net benefits of 0.094 (95% central range -0.083 to 0.267) and 0.146 (-0.029 to 0.322) QALYs. Positive incremental net benefits resulted for high dose dabigatran in 94% of simulations versus warfarin and in 76% of those versus low dose dabigatran. In the economic analysis, high dose dabigatran dominated the low dose, had an incremental cost effectiveness ratio of £23,082 (€26,700; $35,800) per QALY gained versus warfarin, and was more cost effective in patients with a baseline CHADS(2) score of 3 or above. However, at centres that achieved good control of international normalised ratio, such as those in the UK, dabigatran 150 mg was not cost effective, at £42,386 per QALY gained.ConclusionsThis analysis supports regulatory decisions that dabigatran offers a positive benefit to harm ratio when compared with warfarin. However, no subgroup for which dabigatran 110 mg offered any clinical or economic advantage over 150 mg was identified. High dose dabigatran will be cost effective only for patients at increased risk of stroke or for whom international normalised ratio is likely to be less well controlled.

Project description:BackgroundAlthough warfarin has been extensively studied in clinical trials, little is known about rates of hemorrhage attributable to its use in routine clinical practice. Our objective was to examine incident hemorrhagic events in a large population-based cohort of patients with atrial fibrillation who were starting treatment with warfarin.MethodsWe conducted a population-based cohort study involving residents of Ontario (age ≥ 66 yr) with atrial fibrillation who started taking warfarin between Apr. 1, 1997, and Mar. 31, 2008. We defined a major hemorrhage as any visit to hospital for hemorrage. We determined crude rates of hemorrhage during warfarin treatment, overall and stratified by CHADS(2) score (congestive heart failure, hypertension, age ≥ 75 yr, diabetes mellitus and prior stroke, transient ischemic attack or thromboembolism).ResultsWe included 125 195 patients with atrial fibrillation who started treatment with warfarin during the study period. Overall, the rate of hemorrhage was 3.8% (95% confidence interval [CI] 3.8%-3.9%) per person-year. The risk of major hemorrhage was highest during the first 30 days of treatment. During this period, rates of hemorrhage were 11.8% (95% CI 11.1%-12.5%) per person-year in all patients and 16.7% (95% CI 14.3%-19.4%) per person-year among patients with a CHADS(2) scores of 4 or greater. Over the 5-year follow-up, 10 840 patients (8.7%) visited the hospital for hemorrhage; of these patients, 1963 (18.1%) died in hospital or within 7 days of being discharged.InterpretationIn this large cohort of older patients with atrial fibrillation, we found that rates of hemorrhage are highest within the first 30 days of warfarin therapy. These rates are considerably higher than the rates of 1%-3% reported in randomized controlled trials of warfarin therapy. Our study provides timely estimates of warfarin-related adverse events that may be useful to clinicians, patients and policy-makers as new options for treatment become available.

Project description:Atrial fibrillation (AF) increases risk of stroke, and although this stroke risk can be ameliorated by warfarin therapy, some patients decline to adhere to warfarin therapy. A prospective clinical study could be conducted to determine whether knowledge of genetic risk for AF could increase adherence to warfarin therapy for patients who initially declined therapy. As a prelude to a potential prospective clinical study, we investigated whether the use of genetic information to increase adherence could be cost effective.Markov model assessed costs and utilities of two care strategies for AF patients who declined warfarin therapy. In the usual care strategy patients received aspirin. In the test strategy genetic risk for AF was assessed (genotype of the 4q25 locus) and some patients with a positive genetic test (?1 risk allele) were assumed to adhere to warfarin therapy. The remaining patients received aspirin. The incremental cost-effectiveness ratio (ICER) was the ratio of the costs differential and the quality adjusted life-years (QALYs) differential for the two strategies.We found that the 4q25 genetic testing strategy, compared with the usual care strategy (aspirin therapy), would be cost-effective (ICER $ 47,148) if 2.1 % or more of the test positive patients were to adhere to warfarin therapy. The test strategy would become a cost saving strategy if 5.3 % or more of the test positive patients were to adhere to warfarin therapy. If 20 % of test positive patients were to adhere to warfarin therapy in a hypothetical cohort of 1000 patients, 7 stroke events would be prevented and 3 extra-cranial major bleeding events would be caused over 5 years, resulting in a cost savings of?~?$250,000 and a net gain of 9 QALYs.A clinical study to assess the impact of patient knowledge of genetic risk of AF on adherence to warfarin therapy would be merited because even a modest increase in patient adherence would make a genetic testing strategy cost-effective.Providing patients who declined warfarin therapy with information about their genetic risk of AF would be cost effective if this genetic risk information resulted in modest increases in adherence.

Dataset Information

Can We Predict Individual Combined Benefit and Harm of Therapy? Warfarin Therapy for Atrial Fibrillation as a Test Case.

Objectives

Methods

Results

Conclusions

Publications

Can We Predict Individual Combined Benefit and Harm of Therapy? Warfarin Therapy for Atrial Fibrillation as a Test Case.

Similar Datasets

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