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Writing the Introduction Section
Example of a Well-Written Introduction (Clinical Study)
Antiphospholipid antibodies, which include anticardiolipin antibodies and lupus anticoagulant, are associated with both arterial and venous thrombosis. 1 After a first episode of thrombosis, patients with antiphospholipid antibodies have a higher risk of recurrent thrombosis than do patients without antiphospholipid antibodies. 1 Retrospective studies suggest that patients with antiphospholipid antibodies have a high risk of recurrent thrombosis while receiving moderate-intensity warfarin therapy [target international normalized ratio (INR), 2.0 to 3.0] and that this risk is lower with a higher intensity of warfarin therapy (target INR, above 3.0). 2–4 However, these results must be interpreted with caution because the studies were retrospective case series, recurrent thrombosis was not confirmed by standardized methods, and the INR at the time of the thrombotic events was uncertain. Furthermore, the patients in these studies attended special clinics where the staff had an interest in the management of complex problems in patients with antiphospholipid antibodies and the patients were therefore likely to be in a selected group at high risk for recurrent thrombosis. To our knowledge, there have been no randomized trials of the efficacy and safety of high-intensity versus moderate-intensity warfarin therapy in patients with the antiphospholipid antibody syndrome. Because increasing the target INR from a range of 2.0 to 3.0 to a range of 3.1 to 4.0 is likely to be associated with a doubling of the risk of major hemorrhage, it is important to know whether the higher-intensity treatment is more effective. 5,6 To test the hypothesis that high-intensity warfarin therapy is more effective than moderate-intensity warfarin therapy in patients with antiphospholipid antibodies and a previous episode of thrombosis, we undertook a randomized, double-blind trial to compare long-term warfarin therapy targeted to an INR of 2.0 to 3.0 with therapy targeted to an INR of 3.1 to 4.0.
Adapted from Crowther MA, Ginsberg JS, Julian J, et al. A comparison of 2 intensities of warfarin for the prevention of recurrent thrombosis in patients with the antiphospholipid antibody syndrome. N Engl J Med 349:1133–1138, 2003.
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