To the Editor:—The work by Ganz et al.1 demonstrates noncompliance with guidelines for warfarin therapy following a thromboembolic event. However, the current extent of the problem is, perhaps, not well addressed by this study, which used patients from 1991–1994. Though the practice of three months of oral anticoagulation has been recommended by Hyers et al. in 1989,2 the optimal duration of treatment was not yet fully established in 1994. Indeed, Hyers et al. qualified their recommendation, noting that “sufficient length of treatment may be shorter than three months.” In October, 1992, the Research Committee of the British Thoracic Society published their data in support of three months of treatment rather than four weeks.3 Ultimately, two more studies were published in 1995,4,5 which seem to have finally resolved this issue in favor of three months of treatment. Therefore, the compliance problems that have been demonstrated for 1991–94 may have simply reflected some of the uncertainty, which legitimately existed at that time.
Gantz et al. have effectively demonstrated a problem of compliance with guidelines that were, however, evolving at the time of their study. This work establishes the need for further research regarding adherence to current guidelines. Unfortunately, some have now begun to raise concerns that treatment beyond three months for these patients may not be warranted. Such ongoing evolution of guidelines will make evaluation of compliance difficult. —Stuart Keith Sutton, MD, FACP.