By Dr. Robles
The American Society of Hematology Meeting held its annual medical conference in December. Some of the more interesting presentations at this meeting involved deep vein thrombosis.
For patients who have completed therapy with blood thinners after a blood clot, there is uncertainty about what to do next. Typically, patients in the US will complete 6-12 months of warfarin and then be observed closely. Lifelong anticoagulation decreases the risk of a recurrent blood clot, but is associated with a risk of bleeding, and the inconvenience and cost of testing. At this time, there are no features which predict for a high enough risk for recurrent VTE to recommend lifelong anticoagulation. The Warfasa trial was conducted in Italy. Patients who have completed 6-12 months of blood thinner for a first time blood clot received either aspirin or placebo for at least 2 years. Aspirin reduced the risk of a recurrent blood count: 11% for placebo and 6.3% for aspirin. There was no difference between placebo and aspirin in regards to bleeding episodes. Aspirin represents a reasonable option for doctors and patients worried about blood count recurrence after completion of 6-12 months of blood thinner. However, only a head to head trial of aspirin versus longer treatment with warfarin would answer the question of the preferred option.
Which patients require long term blood thinner treatment? An international group of investigators evaluated patients who had been treated on clinical trials for first blood clots treated with at least 3 months with warfarin. An elevated D-Dimer blood test following completion of blood thinner therapy, age <50, male sex, and blood clots not associated with hormone use (women only) at the time of blood clot diagnosis were risk factors for recurrent blood clots. The DASH score was developed: +2 points for abnormal D-Dimer, +1 point for men, +1 point for age <50, and -2 points for hormone use.The risk of recurrent blood clot was 3.1% in patients with a DASH score ≤ 1, 6.4% with a DASH score 2, and 12.3% in patients with a DASH score ≥ 3. By considering patients with a DASH score ≤ 1; life-long blood thinner therapy might be avoided in 51.6% of patients with first time blood clot. Although easy to use and attractive, it requires further confirmation.
Finally, Doctors from Norway reported a randomized trial comparing standard blood thinner therapy to blood thinner and additional clot dissolving drug given by direct delivery through a catheter inserted into the vein with the blood clot (CDT). The purpose of this trial was to determine whether more aggressive treatment would decrease pain and swelling in the leg which can occur after a blood clot, postphlebitic syndrome. After 24 months, 41.1% receiving catheter directed therapy presented with postphlebitic syndrome compared to 55.6% in the standard blood thinner treated group. In total 20 bleeding complications were reported; 3 were classified as major and 5 as clinically relevant. The majority of bleeding complications were related to the puncture site. So, is this the final word on treatment of leg blood clots? Probably not. Another larger, randomized trial is underway in the U.S. and should provide more definitive findings. CDT seems to be a reasonable adjunct for appropriate patients if the expertise and facilities are readily available, pending results from the U.S. randomized trial.
The American Society of Hematology Meeting held its annual medical conference in December. Some of the more interesting presentations at this meeting involved deep vein thrombosis.
For patients who have completed therapy with blood thinners after a blood clot, there is uncertainty about what to do next. Typically, patients in the US will complete 6-12 months of warfarin and then be observed closely. Lifelong anticoagulation decreases the risk of a recurrent blood clot, but is associated with a risk of bleeding, and the inconvenience and cost of testing. At this time, there are no features which predict for a high enough risk for recurrent VTE to recommend lifelong anticoagulation. The Warfasa trial was conducted in Italy. Patients who have completed 6-12 months of blood thinner for a first time blood clot received either aspirin or placebo for at least 2 years. Aspirin reduced the risk of a recurrent blood count: 11% for placebo and 6.3% for aspirin. There was no difference between placebo and aspirin in regards to bleeding episodes. Aspirin represents a reasonable option for doctors and patients worried about blood count recurrence after completion of 6-12 months of blood thinner. However, only a head to head trial of aspirin versus longer treatment with warfarin would answer the question of the preferred option.
Which patients require long term blood thinner treatment? An international group of investigators evaluated patients who had been treated on clinical trials for first blood clots treated with at least 3 months with warfarin. An elevated D-Dimer blood test following completion of blood thinner therapy, age <50, male sex, and blood clots not associated with hormone use (women only) at the time of blood clot diagnosis were risk factors for recurrent blood clots. The DASH score was developed: +2 points for abnormal D-Dimer, +1 point for men, +1 point for age <50, and -2 points for hormone use.The risk of recurrent blood clot was 3.1% in patients with a DASH score ≤ 1, 6.4% with a DASH score 2, and 12.3% in patients with a DASH score ≥ 3. By considering patients with a DASH score ≤ 1; life-long blood thinner therapy might be avoided in 51.6% of patients with first time blood clot. Although easy to use and attractive, it requires further confirmation.
Finally, Doctors from Norway reported a randomized trial comparing standard blood thinner therapy to blood thinner and additional clot dissolving drug given by direct delivery through a catheter inserted into the vein with the blood clot (CDT). The purpose of this trial was to determine whether more aggressive treatment would decrease pain and swelling in the leg which can occur after a blood clot, postphlebitic syndrome. After 24 months, 41.1% receiving catheter directed therapy presented with postphlebitic syndrome compared to 55.6% in the standard blood thinner treated group. In total 20 bleeding complications were reported; 3 were classified as major and 5 as clinically relevant. The majority of bleeding complications were related to the puncture site. So, is this the final word on treatment of leg blood clots? Probably not. Another larger, randomized trial is underway in the U.S. and should provide more definitive findings. CDT seems to be a reasonable adjunct for appropriate patients if the expertise and facilities are readily available, pending results from the U.S. randomized trial.
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