(Dr. Forbes replies)
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* Thomas L. Forbes

We welcome Mr. Suissa’s comments on our paper regarding the role for long-term anticoagulation after acute thromboembolic limb ischemia. 1 He makes good points, outlining some of the weaknesses of all retrospective studies, which we recognize in our paper. Although in principle I agree with his general epidemiologic arguments, I do not agree that patients with malignant disease or those who underwent amputation should be removed from our analysis.

The purpose of our study was to analyze the natural history of patients who suffered from acute thromboembolic limb ischemia in the presence or absence of certain risk factors and long-term anticoagulation. Although patients in group 2 did contain a significant number of patients with malignant disease, these patients should be included in the outcome analysis because this is a recognized predisposing factor for recurrent venous and arterial thrombosis. In regard to the inclusion of the 4 patients who underwent early extremity amputation, it is important that these patients be included as they are at risk for recurrent arterial events, which was one of our main outcome variables.

Suissa’s comments are appreciated and serve to reinforce the limitations of all retrospective studies. However, these studies can propose trends that can be subsequently explored with prospective, randomized studies.

## Reference

1.  Forbes TL, DeRose G, Harris KA. Is long-term anticoagulation after acute thromboembolic limb ischemia always necessary? Can J Surg 2002;45:337–40.