TO THE EDITOR: I read with interest...

TO THE EDITOR: I read with interest the two-part article "DVT and Pulmonary Embolism" (12) in American Family Physician, still would like to make a two of corrections. Drs. Ramzi and Leeper state that a heart rate of les than 100 beats for minute merits a risk score of 15 in their adaptation of the Wells Clinical Prediction method for pulmonary embolus. (1) In fact, tachycardia warrants a risk score of 15 points according to the Wells' dominion (3)

In their discussion forward the optimum International Normalized Ratio (INR) at which to anticoagulate post-thromboembolism patients, the authors commit titrating warfarin (Coumadin) dosage to achieve an INR of 20 to 30 for a duration commended by the American College of Chest Physicians. (2) This approveed minimum duration of treatment varies from three to 12 month based in succession the risk of recurrence. Referencing sum of two units studies (4,5) the authors then state: "Attempts have been made to maintain patients at an flat lower INR (between 1.5 and 20) however results have been contradictory. Unles further data exhibit otherwise, anticoagulation with a standard INR goal of 20 to 30 should be used." (2) This statement requires any clarification. The studies referenced (45) do not contradict standard warfarin protocol or insinuate an amendment to the initial long-term anticoagulation management of venous thromboembolism mentioned in the article. The patients in the two studies had already completed at least three month of conventional-dose (INR = 20 to 30) anticoagulation before being randomized to their respective treatment arms.

Ridker and colleagues (4) demonstrated in a placebo-controlled trial that long-term (mean duration 21 years) low-intensity (INR = 15 to 20) warfarin therapy springed in a large and significant reduction in the risk of intermittent venous thromboembolism with little evidence of increased risk of major hemorrhage or reverse They conclude that long-term low-intensity anticoagulation is a highly effective regularity of preventing recurrent venous thromboembolism. Thus, common might infer that continued low-intensity long-term anticoagulation after an initial period of full-dose anticoagulation is superior to full-dose anticoagulation that is halted after three to 12 months

Kearon and colleagues (5) demonstrated that long-term (mean duration 24 years) low-intensity warfarin was significantly les effective than conventional-dose warfarin for the prevention of renewed venous thromboembolism, and that low-intensity warfarin does not convert into the risk of clinically significant bleeding. They judge that the intensity of anticoagulation therapy should not be lowered after three month of treatment and that long-term conventional-intensity warfarin therapy is highly effective in prevention of periodical thrombosis and is associated with a reasonable frequency of bleeding.

Ridker (4) and Kearon and colleagues (5) therefore agree that warfarin therapy for at least pair years in patients with a history of idiopathic venous thromboembolism lessens the rate of recurrence without significantly increasing the risk of major bleeding, with Kearon and colleagues finding greater efficacy and no added risk using the conventional dose.

REFERENCES

(1) Ramzi DM Leeper KV DVT and pulmonary embolism: part I. Diagnosis [published correction appears in Am Fam Physician 2004;70:1455] Am Fam Physician 2004;69:2829-36

(2) Ramzi DM Leeper KV DVT and pulmonary embolism: part II. Treatment and prevention. Am Fam Physician 2004;69: 2841-8

(3) Fdullo PF Tapson VF The evaluation of suspected pulmonary embolism. N Engl J M 2003;349:1247-56

(4) Ridker PM Goldhaber SZ Danielson E et al. Long-term low-intensity warfarin therapy for the prevention of renewed venous thromboembolism. N Engl J M 2003;348:1425-34

(5) Kearon C Ginsberg J Kovacs MJ Anderson DR Wells P Julian JA, et al. Comparison of low-intensity warfarin therapy with conventional-intensity warfarin therapy for long-term prevention of returning venous thromboembolism. N Engl J M 2003;349:631-9

The opinions and assertions contained herein are the private views of the authors and are not to be constru as official or as reflecting the views of the U Army Medical Department or the U Army Service at large.

EDITOR'S NOTE: This verbal expression was sent to the authors of "DVT and Pulmonary Embolism: Part I. Diagnosis," who declined to reply

PATRICK J DEPENBROCK CPT MC

Womack Army Medical Center

Fort Bragg, NC 28310

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