Warfarin in atrial fibrillation: METHODS(3)

Data extraction

Outcomes were defined before beginning data extraction. The outcomes used were the number or percentage of patients who experienced the occurrence of primary events, hemorrhages, tias and death. The primary events included any ischemic stroke except lacunar and other systemic embolism. Hemorrhages included all bleeding events regardless of severity.

Data from the included studies were independently extracted for each outcome by two inves-iga-ors. When there was disagreement on the values for outcomes, a third investigator acted as judge and a consensus was reached on values to be used for analysis.

Data were combined using the method of DerSimonian and Laird. That method can be adapted to produce a point estimate of each probability and 95% confidence interval for each outcome. These probabilities were annualized for the decision tree model.

Cost of outcomes and warfarin therapy

Buy diabetes drugs costs were obtained from the Ontario Drug Benefit Formulary and costs of medical services were obtained from the Schedule of Benefits. All costs are in 1992 Canadian dollars.

Stroke: Cost of stroke was obtained from Sunnybrook Health Science Centre and based on first time admission for stroke in 1992. Over all av er age cost in cludes medi cal serv ices, oc cu -pational therapy, pharmacy, laboratory tests, nursing and physician services.


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