Archive for the ‘Warfarin’ Category

Warfarin in atrial fibrillation: LIMITATIONS AND FUTURE CONSIDERATIONS(2)

LIMITATIONS AND FUTURE CONSIDERATIONS(2)

Further studies should try to address risk/ benefit factors by stratifymg patients based on age and underlymg factors that are commonly associated with atrial fibrillation, such as heart disease and hypertension. The presence of two or more factors increases the risk of developmg stroke up to 17.6% per yea. Further studtes also need to assess how long war farin therapy should be con tin ued, especially with older patients who are more likely to have bleeding complications over time. ventolin inhaler

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Warfarin in atrial fibrillation: LIMITATIONS AND FUTURE CONSIDERATIONS(1)

This cost-effectiveness analysis is based on the results of a meta-analysis and costs of events obtained from Sunnybrook Health Science Centre. Costs for major and minor events in this analytis were obtained from one hospital in Totonto, which may not necessarily be the same at other hospitals across Canada. A more general description of costs would involve cost data (including participation from an expert panel) from several hospitals in different regions.

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Warfarin in atrial fibrillation: DISCUSSION(3)

Warfarin in atrial fibrillation: DISCUSSION(3)

Bleeding complications are perhap s the biggest concern for indicated patients. New studies in Europe and phase 2 of the Stroke Prevention in Atrial Fibrillation study comparing warfarin with asa suggest patients 75 years and over should use warfarin (low intensity) and asa to reduce stroke risk and major bleeding complications. Also, low risk stroke patients (2%/ year) bet ween 60 and 75 years old appear to be adequately protected against stroke with asa therapy. These findings need to be confirmed with prospective trials such as phase 3 of the Stroke Prevention in Atrial Fibrillation study, cur rently in progress.

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Warfarin in atrial fibrillation: DISCUSSION(2)

The results from this cost-effectiveness analysis become even more dramatic when applied to the Canadian population. Using 1991 census data (the most recently available), a net savings to the health care system is realized when warfarin is used on indicated people. Up to 1.25% major complication rate will still result in a net savings (Tables 8-10). Similar results were also found in a Swedish study, indicating a net savings up to a 1.3% major bleeding complication rate. The critical value here is the rate of major bleeding which increases with age. buy flovent inhaler

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Warfarin in atrial fibrillation: DISCUSSION(1)

This study assessed the cost-effectiveness ofwarfarin intervention versus placebo from society’s perspective. Clearly, this analysis shows a protective effect with warfarin (66% reduction in embolic events) compared with no antithrombotic therapy. The data from these clinical trials, when combined, provide physicians with strong evidence to use warfarin routinely for those who qualify. A simiiar reduction in embolic events was also found (64% reduction) by investigators using the total Swedish population.

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Warfarin in atrial fibrillation: RESULTS(1)

Meta-analysis

Five studies were deemed eligible for meta-analysis based on the inclusion criteria and are listed in Table 1.

TABLE 1

Studies on the efficacy of warfarin in the prevention of stroke in atrial fibrillation patients included in the metaanalysis

Study(reference) Type of study Blinding INR PT ratio
AFASAK (4) Prospective, randomized, placebo controlled* Open 2.8-4.2 1.5-2.0
BAATAF (5) Prospective, randomized, not placebo controlled (patient allowed to take ASA in control group) Nonblinded 1.5-2.7 1.2-1.5
CAFA (6) Prospective, randomized, placebo controlled Triple-blinded’1 2-3 1.3-1.6
SPAF (7) Prospective, randomized, placebo controlled* Doubleblinded 2-4.5 1.3-1.8
SPINAF (8) Prospective, randomized, placebo controlled Doubleblinded 1.4-2.8 1.2-1.5

*A third study group received acetylsalicylic acid (ASA) 75 mg/day but was not examined in this meta-analysis; fBlinding to patient, physician and treatment centre; *A third study group received ASA 325 mg/ day but those results were not reported in the study and were not examined in this meta-analysis. AFASAK Copenhagen Atrial Fibrillation trial; BAATAF Boston Area Anticoagulation Trial for Atrial Fibrillation; CAFA Canadian Atrial Fibrillation Anticoagulation study; INR International Normalized Ratio; PT Prothrombin time; SPAF Stroke Prevention in Atrial Fibrillation study; SPINAF Stroke Prevention In Nonrheumatic Atrial Fibrillation study

The results of the analyses of the four outcomes assessed in 2415 patients are presented in Table 2. All data used in this meta-analysis were extracted from the intention-to-treat values given in the reports of each study. Table 3 summarizes the results of the five studies and annualizes the values for use in the pharmacoeconomic analysis since the average follow-up period for all studies in Table 1 is greater then one year. cialis professional 20 mg

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Warfarin in atrial fibrillation: METHODS(5)

Warfarin in atrial fibrillation: METHODS(5)

Analysis of data

Outcomes for each intervention (ie, warfarin and no antithrombotic therapy) were analyzed in the decision tree model based on their individual probabilities and costs. Pathway probabilities were multiplied by the sum of the pathway cost to derive an expected cost (Figure 1) for each pathway. Sensitivity analysis was performed on three baseline variables in the warfarin branch (probabilities of minor bleed, major bleed and emboli) to assess the robustness of the data. Break-even analysis was also performed on these variables and the cost of warfarin therapy to determine at which point the two interventions consume identical expected costs. buy ortho tri-cyclen

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