To the Editor: The otherwise excellent and comprehensive Current Concepts review by Adar and Salzman, “Treatment of Thrombosis of Veins of the Lower Extremities,” (February 13) fails to mention some aspects of the treatment of deep vein thrombosis, on which I should like to comment. Once anticoagulant treatment is effective, I have always encouraged patients to walk, provided the pain has decreased. Elastic support is needed at this stage to control edema. There seems to be no good reason for keeping patients in bed for long periods. Upon discharge from the hospital, with long-term warfarin sodium (Coumadin) administration, I have.