Study design: Patient-level meta-analysis.
Setting: Pooled patient-level data from seven prospective studies.
Synopsis: Patient-level data were obtained for all patients enrolled using post-treatment D-dimer measurement to predict recurrent VTE in patients with a first unprovoked VTE who had completed at least three months of anticoagulation therapy. The mean length of follow-up was 30 months. Patients with a positive D-dimer had recurrent VTE at a rate of 8.8 per 100 patient-years while those with a negative D-dimer had a rate of 3.7 per 100 patient-years.
Univariate analysis revealed an HR of 2.59 for patients with a positive versus a negative test result. The analysis also showed that the timing of the test, the age of the patient, and the actual cut points used for the various D-dimer tests did not affect the analysis significantly.
These studies’ strength is their large sample sizes and the use of prospective studies. The weaknesses include a mostly white patient population and incomplete data on all patients.
Bottom line: D-dimer testing is useful in predicting VTE recurrence after treatment for a first unprovoked event regardless of patient age, post-treatment timing, or the assay cut point used.
Citation: Douketis J, Tosetto A, Marcucci M, et al. Patient-level meta-analysis: effect of measurement timing, threshold, and patient age on ability of D-dimer testing to assess recurrence risk after unprovoked venous thromboembolism. Ann Intern Med. 2010;153(8): 523-531.
Thigh-High Stockings Are Better than Knee-High Stockings for Post-Stroke DVT Prophylaxis
Clinical question: Are thigh-high compression stockings better then knee-high stockings in immobilized acute-stroke patients?
Background: DVT is common in hospitalized stroke patients with immobility. Graduated compression stockings are often used for DVT prophylaxis, but the CLOTS-1 trial recently found that thigh-high stockings were ineffective after acute stroke. It is unclear if the more commonly used knee-high stockings are more effective than thigh-high stockings.
Study design: Parallel-group trial (the CLOTS-2 trial).
Setting: One hundred twelve hospitals in nine countries.
Synopsis: More than 3,100 patients with acute stroke and immobilization were recruited from January 2002 to May 2009. Patients were randomized to receive thigh-high or knee-high stockings. Patients also received usual care, including anticoagulants and a screening ultrasound for asymptomatic proximal DVT at seven to 10 days. Approximately 640 patients in each group also underwent ultrasound at 25-30 days.
Overall, 6.3% of patients in the thigh-high group had DVT, compared with 8.8% in the knee-high group (P=0.007). There were no significant differences in the secondary outcomes of pulmonary embolism or death. The thigh-high stockings had a higher number of adverse skin events. Enrollment was stopped early when the CLOTS-1 trial showed no difference in DVT rates between thigh-high stockings and no stockings.
Bottom line: Knee-high graduated compression stockings lead to worse outcomes than thigh-high stockings for DVT prophylaxis in immobilized acute-stroke patients.
Citation: CLOTS (Clots in Legs Or sTockings after Stroke) Trial Collaboration. Thigh-length versus below-knee stockings for deep venous thrombosis prophylaxis after stroke: a randomized trial. Ann Intern Med. 2010;153(9):553-562. TH