Diagnosis of Pulmonary Embolism with d-Dimer Adjusted to Clinical Probability.

BACKGROUND: Retrospective analyses suggest that pulmonary embolism is ruled out by a d-dimer level of less than 1000 ng per milliliter in patients with a low clinical pretest probability (C-PTP) and by a d-dimer level of less than 500 ng per milliliter in patients with a moderate C-PTP. METHODS: We performed a prospective study in which pulmonary embolism was considered to be ruled out without further testing in outpatients with a low C-PTP and a d-dimer level of less than 1000 ng per milliliter or with a moderate C-PTP and a d-dimer level of less than 500 ng per milliliter. All other patients underwent chest imaging (usually computed tomographic pulmonary angiography). If pulmonary embolism was not diagnosed, patients did not receive anticoagulant therapy. All patients were followed for 3 months to detect venous thromboembolism. RESULTS: A total of 2017 patients were enrolled and evaluated, of whom 7.4% had pulmonary embolism on initial diagnostic testing. Of the 1325 patients who had a low C-PTP (1285 patients) or moderate C-PTP (40 patients) and a negative d-dimer test (i.e., <1000 or <500 ng per milliliter, respectively), none had venous thromboembolism during follow-up (95% confidence interval [CI], 0.00 to 0.29%). These included 315 patients who had a low C-PTP and a d-dimer level of 500 to 999 ng per milliliter (95% CI, 0.00 to 1.20%). Of all 1863 patients who did not receive a diagnosis of pulmonary embolism initially and did not receive anticoagulant therapy, 1 patient (0.05%; 95% CI, 0.01 to 0.30) had venous thromboembolism. Our diagnostic strategy resulted in the use of chest imaging in 34.3% of patients, whereas a strategy in which pulmonary embolism is considered to be ruled out with a low C-PTP and a d-dimer level of less than 500 ng per milliliter would result in the use of chest imaging in 51.9% (difference, -17.6 percentage points; 95% CI, -19.2 to -15.9). CONCLUSIONS: A combination of a low C-PTP and a d-dimer level of less than 1000 ng per milliliter identified a group of patients at low risk for pulmonary embolism during follow-up. (Funded by the Canadian Institutes of Health Research and others; PEGeD ClinicalTrials.gov number, NCT02483442.).

Rivaroxaban Compared to Placebo for the Treatment of Leg Superficial Vein Thrombosis: A Randomized Trial.

The role of rivaroxaban in the treatment of leg superficial venous thrombosis (SVT) is uncertain. This article aims to determine if rivaroxaban is an effective and safe treatment for leg SVT. Patients with symptomatic leg SVT of at least 5 cm length were randomized to 45 days of rivaroxaban 10 mg daily or to placebo, and followed for a total of 90 days. Treatment failure (required a nonstudy anticoagulant; had proximal deep vein thrombosis or pulmonary embolism; or had surgery for SVT) at 90 days was the primary efficacy outcome. Secondary efficacy outcomes included leg pain severity, and venous disease-specific and general health-related quality of life over 90 days. Major bleeding at 90 days was the primary safety outcome. Poor enrollment led to the trial being stopped after 85 of the planned 600 patients were randomized to rivaroxaban (n = 43) or placebo (n = 42). One rivaroxaban and five placebo patients had a treatment failure by 90 days (absolute risk reduction = 9.0%, 95% confidence interval: -22 to 5.9%). Leg pain improvement did not differ at 7 (p = 0.16) or 45 days (p = 0.89), but was greater with rivaroxaban at 90 days (p = 0.011). There was no difference in venous disease-specific (p = 0.99) or general health-related (p = 0.37) quality of life over 45 days. There were no major bleeds or deaths in either group. There were no identifiable differences in efficacy or safety between rivaroxaban and placebo in patients with symptomatic SVT but comparisons were undermined by a much smaller than planned sample size (NCT1499953).

Warfarin dose assessment every 4 weeks versus every 12 weeks in patients with stable international normalized ratios: a randomized trial.

BACKGROUND: Guidelines recommend that patients receiving warfarin undergo international normalized ratio (INR) monitoring every 4 weeks. OBJECTIVE: To investigate whether assessment of warfarin dosing every 12 weeks is as safe as assessment every 4 weeks. DESIGN: Noninferiority randomized trial. The randomization schedule (in a 1:1 ratio) was computer-generated, and allocation was concealed until the database was locked by using a centralized schedule. Patients, study and clinical personnel, adjudicators of clinical events, and the study statistician were blinded to treatment assignment. (ClinicalTrials.gov registration number: NCT00356759) SETTING: Single center in Hamilton, Ontario, Canada. PATIENTS: 250 patients receiving long-term warfarin therapy, whose dose was unchanged for at least 6 months; 226 completed the study. INTERVENTION: Dosing assessment every 12 weeks (n = 124) compared with every 4 weeks (n = 126) for 12 months. Patients in the 12-week group were tested every 4 weeks; sham INRs within the target range were reported for two of the three 4-week periods. MEASUREMENTS: Percentage of time in the therapeutic range (primary outcome) and number of extreme INRs, changes in maintenance dose, major bleeding events, objectively verified thromboembolism, and death (secondary outcomes). RESULTS: The percentage of time in the therapeutic range was 74.1% (SD, 18.8%) in the 4-week group compared with 71.6% (SD, 20.0%) in the 12-week group (absolute difference, 2.5 percentage points [1-sided 97.5% upper confidence bound, 7.3 percentage points]; noninferiority P = 0.020 for a 7.5-percentage point margin). Fewer patients in the 12-week group than in the 4-week group had any dose changes (37.1% vs. 55.6%; absolute difference, 18.5 percentage points [95% CI, 6.1 to 30.0 percentage points]; P = 0.004). Secondary outcomes did not differ between groups. LIMITATIONS: Patients in the 12-week group had testing and contact with clinic staff every 4 weeks. The study was conducted at a single center and used surrogate outcomes. CONCLUSION: Assessment of warfarin dosing every 12 weeks seems to be safe and noninferior to assessment every 4 weeks. A comparison of INR testing, patient contact, and warfarin dose assessment every 12 weeks versus every 4 weeks is necessary before INR testing every 12 weeks can be routinely recommended for practice. PRIMARY FUNDING SOURCE: Physicians' Services Incorporated Foundation.