Approximately 30% of patients with an episode of adequately treated deep venous thrombosis (DVT) develop post-thrombotic syndrome (PTS) within 2 years. Studies have shown that the average patient treated with warfarin spends only 60% of the time in his or her goal international normalized ratio (INR) range of 2.0 to 3.0. A recent investigation of the relationship between subtherapeutic INRs and PTS demonstrated that patients who spent more than 50% of their time below an INR of 2.0 had an almost 3-fold risk of developing PTS. Patients in this study were treated with warfarin for at least 3 months and were followed for a maximum of 5 years to assess for signs, symptoms, and severity of PTS.
The authors concluded that low-quality treatment with warfarin is related to the occurrence of PTS in patients with DVT. Strategies aimed at improving the quality of long-term anticoagulation may have the potential to reduce the incidence of this complication.
Dr. Garrett is a clinical pharmacist practitioner at Cornerstone Health Care in High Point, NC.
One study linked multiple pregnancies to an increased risk of developing atrial fibrillation later in life, and another investigated the association between premature delivery and cardiovascular disease.
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