Indefinite Anticoagulant Therapy for First Unprovoked Venous Thromboembolism : A Cost-Effectiveness Study.

BACKGROUND: Clinical practice guidelines recommend indefinite anticoagulation for a first unprovoked venous thromboembolism (VTE). OBJECTIVE: To estimate the benefit-harm tradeoffs of indefinite anticoagulation in patients with a first unprovoked VTE. DESIGN: Markov modeling study. DATA SOURCES: Systematic reviews and meta-analyses for the long-term risks and case-fatality rates of recurrent VTE and major bleeding. Published literature for costs, quality of life, and other clinical events. TARGET POPULATION: Patients with a first unprovoked VTE who have completed 3 to 6 months of initial anticoagulant treatment. TIME HORIZON: Lifetime. PERSPECTIVE: Canadian health care public payer. INTERVENTION: Indefinite anticoagulation with direct oral anticoagulants. OUTCOME MEASURES: Recurrent VTE events, major bleeding events, costs in 2022 Canadian dollars (CAD), and quality-adjusted life-years (QALYs). RESULTS OF BASE-CASE ANALYSIS: When compared with discontinuing anticoagulation after initial treatment in a hypothetical cohort of 1000 patients aged 55 years, indefinite anticoagulation prevented 368 recurrent VTE events, which included 14 fatal pulmonary emboli, but induced an additional 114 major bleeding events, which included 30 intracranial hemorrhages and 11 deaths from bleeding. Indefinite anticoagulation cost CAD $16 014 more per person and did not increase QALYs (-0.075 per person). RESULTS OF SENSITIVITY ANALYSIS: Model results were most sensitive to the case-fatality rate of major bleeding and the annual risk for major bleeding during extended anticoagulation. LIMITATION: The model assumed that risks for recurrent VTE and major bleeding measured in clinical trials at 1 year remained constant during extended anticoagulation. CONCLUSION: Clinicians should use shared decision making to incorporate individual patient preferences and values when considering treatment duration for unprovoked VTE. PRIMARY FUNDING SOURCE: Canadian Institutes of Health Research.

Intermediate-dose versus low-dose low-molecular-weight heparin in pregnant and post-partum women with a history of venous thromboembolism (Highlow study): an open-label, multicentre, randomised, controlled trial.

BACKGROUND: Pregnancy-related venous thromboembolism is a leading cause of maternal morbidity and mortality, and thromboprophylaxis is indicated in pregnant and post-partum women with a history of venous thromboembolism. The optimal dose of low-molecular-weight heparin to prevent recurrent venous thromboembolism in pregnancy and the post-partum period is uncertain. METHODS: In this open-label, randomised, controlled trial (Highlow), pregnant women with a history of venous thromboembolism were recruited from 70 hospitals in nine countries (the Netherlands, France, Ireland, Belgium, Norway, Denmark, Canada, the USA, and Russia). Women were eligible if they were aged 18 years or older with a history of objectively confirmed venous thromboembolism, and with a gestational age of 14 weeks or less. Eligible women were randomly assigned (1:1), before 14 weeks of gestational age, using a web-based system and permuted block randomisation (block size of six), stratified by centre, to either weight-adjusted intermediate-dose or fixed low-dose low-molecular-weight heparin subcutaneously once daily until 6 weeks post partum. The primary efficacy outcome was objectively confirmed venous thromboembolism (ie, deep-vein thrombosis, pulmonary embolism, or unusual site venous thrombosis), as determined by an independent central adjudication committee, in the intention-to-treat (ITT) population (ie, all women randomly assigned to treatment). The primary safety outcome was major bleeding which included antepartum, early post-partum (within 24 h after delivery), and late post-partum major bleeding (24 h or longer after delivery until 6 weeks post partum), assessed in all women who received at least one dose of assigned treatment and had a known end of treatment date. This study is registered with ClinicalTrials.gov, NCT01828697, and is now complete. FINDINGS: Between April 24, 2013, and Oct 31, 2020, 1339 pregnant women were screened for eligibility, of whom 1110 were randomly assigned to weight-adjusted intermediate-dose (n=555) or fixed low-dose (n=555) low-molecular-weight heparin (ITT population). Venous thromboembolism occurred in 11 (2%) of 555 women in the weight-adjusted intermediate-dose group and in 16 (3%) of 555 in the fixed low-dose group (relative risk [RR] 0·69 [95% CI 0·32-1·47]; p=0·33). Venous thromboembolism occurred antepartum in five (1%) women in the intermediate-dose group and in five (1%) women in the low-dose group, and post partum in six (1%) women and 11 (2%) women. On-treatment major bleeding in the safety population (N=1045) occurred in 23 (4%) of 520 women in the intermediate-dose group and in 20 (4%) of 525 in the low-dose group (RR 1·16 [95% CI 0·65-2·09]). INTERPRETATION: In women with a history of venous thromboembolism, weight-adjusted intermediate-dose low-molecular-weight heparin during the combined antepartum and post-partum periods was not associated with a lower risk of recurrence than fixed low-dose low-molecular-weight heparin. These results indicate that low-dose low-molecular-weight heparin for thromboprophylaxis during pregnancy is the appropriate dose for the prevention of pregnancy-related recurrent venous thromboembolism. FUNDING: French Ministry of Health, Health Research Board Ireland, GSK/Aspen, and Pfizer.

Risk for Recurrent Venous Thromboembolism in Patients With Subsegmental Pulmonary Embolism Managed Without Anticoagulation : A Multicenter Prospective Cohort Study.

BACKGROUND: The incidence of pulmonary embolism has been increasing, but its case-fatality rate is decreasing, suggesting a lesser severity of illness. The clinical importance of patients with pulmonary embolism isolated to the subsegmental vessels is unknown. OBJECTIVE: To determine the rate of recurrent venous thromboembolism in patients with subsegmental pulmonary embolism managed without anticoagulation. DESIGN: Multicenter prospective cohort study. (ClinicalTrials.gov: NCT01455818). SETTING: Eighteen sites between February 2011 and February 2021. PATIENTS: Patients with isolated subsegmental pulmonary embolism. INTERVENTION: At diagnosis, patients underwent bilateral lower-extremity venous ultrasonography, which was repeated 1 week later if results were negative. Patients without deep venous thrombosis did not receive anticoagulant therapy. MEASUREMENTS: The primary outcome was recurrent venous thromboembolism during the 90-day follow-up period. RESULTS: Recruitment was stopped prematurely because the predefined stopping rule was met after 292 of a projected 300 patients were enrolled. Of the 266 patients included in the primary analysis, the primary outcome occurred in 8 patients, for a cumulative incidence of 3.1% (95% CI, 1.6% to 6.1%) over the 90-day follow-up. The incidence of recurrent venous thromboembolism was 2.1% (CI, 0.8% to 5.5%) and 5.7% (CI, 2.2% to 14.4%) over the 90-day follow-up in patients with single and multiple isolated subsegmental pulmonary embolism, respectively. No patients had a fatal recurrent pulmonary embolism. LIMITATION: The study was restricted to patients with low-risk subsegmental pulmonary embolism. CONCLUSION: Overall, patients with subsegmental pulmonary embolism who did not have proximal deep venous thrombosis had a higher-than-expected rate of recurrent venous thromboembolism. PRIMARY FUNDING SOURCE: Heart and Stroke Foundation of Canada and French Ministry of Health Programme Hospitalier de Recherche Clinique.

Recurrence after stopping anticoagulants in women with combined oral contraceptive-associated venous thromboembolism: A systematic review and meta-analysis.

The risk of recurrence after discontinuation of anticoagulation for a combined oral contraceptive (COC)-associated venous thromboembolism (VTE) is unclear. Therefore, we conducted a systematic review and meta-analysis to estimate the incidence of recurrent VTE among women with COC-associated VTE, unprovoked VTE and to compare the incidence of recurrent VTE between the two groups. The Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase Classic +Embase and Medline ALL to July 2020 and citations from included studies were searched. Randomized controlled trials, prospective cohort studies and meta-analyses of these study types were selected. The analysis was conducted by random-effects model. Nineteen studies were identified including 1537 women [5828 person-years (PY)] with COC-associated VTE and 1974 women (7798 PY) with unprovoked VTE. Studies were at low risk of bias. The incidence rate of VTE recurrence was 1.22/100 PY [95% confidence interval (CI) 0.92-1.62, I2  = 6%] in women with COC-associated VTE, 3.89/100 PY (95% CI 2.93-5.17, I2  = 74%) in women with unprovoked VTE and the unadjusted incidence rate ratio was 0.34 (95% CI 0.26-0.46, I2  = 3%). The recurrence risk in women after COC-associated VTE is low and lower than after an unprovoked VTE.

Venous thromboembolism.

Venous thromboembolism, comprising both deep vein thrombosis and pulmonary embolism, is a chronic illness that affects nearly 10 million people every year worldwide. Strong provoking risk factors for venous thromboembolism include major surgery and active cancer, but most events are unprovoked. Diagnosis requires a sequential work-up that combines assessment of clinical pretest probability for venous thromboembolism using a clinical score (eg, Wells score), D-dimer testing, and imaging. Venous thromboembolism can be considered excluded in patients with both a non-high clinical pretest probability and normal D-dimer concentrations. When required, ultrasonography should be done for a suspected deep vein thrombosis and CT or ventilation-perfusion scintigraphy for a suspected pulmonary embolism. Direct oral anticoagulants (DOACs) are the first-line treatment for almost all patients with venous thromboembolism (including those with cancer). After completing 3-6 months of initial treatment, anticoagulation can be discontinued in patients with venous thromboembolism provoked by a major transient risk factor. Patients whose long-term risk of recurrent venous thromboembolism outweighs the long-term risk of major bleeding, such as those with active cancer or men with unprovoked venous thromboembolism, should receive indefinite anticoagulant treatment. Pharmacological venous thromboembolism prophylaxis is generally warranted in patients undergoing major orthopaedic or cancer surgery. Ongoing research is focused on improving diagnostic strategies for suspected deep vein thrombosis, comparing different DOACs, developing safer anticoagulants, and further individualising approaches for the prevention and management of venous thromboembolism.

Long-Term Risk for Major Bleeding During Extended Oral Anticoagulant Therapy for First Unprovoked Venous Thromboembolism : A Systematic Review and Meta-analysis.

BACKGROUND: The long-term risk for major bleeding in patients receiving extended (beyond the initial 3 to 6 months) anticoagulant therapy for a first unprovoked venous thromboembolism (VTE) is uncertain. PURPOSE: To determine the incidence of major bleeding during extended anticoagulation of up to 5 years among patients with a first unprovoked VTE, overall, and in clinically important subgroups. DATA SOURCES: MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from inception to 23 July 2021. STUDY SELECTION: Randomized controlled trials (RCTs) and prospective cohort studies reporting major bleeding among patients with a first unprovoked VTE who were to receive oral anticoagulation for a minimum of 6 additional months after completing at least 3 months of initial anticoagulant treatment. DATA EXTRACTION: Two reviewers independently abstracted data and assessed study quality. Unpublished data required for analyses were obtained from authors of included studies. DATA SYNTHESIS: Among the 14 RCTs and 13 cohort studies included in the analysis, 9982 patients received a vitamin K antagonist (VKA) and 7220 received a direct oral anticoagulant (DOAC). The incidence of major bleeding per 100 person-years was 1.74 events (95% CI, 1.34 to 2.20 events) with VKAs and 1.12 events (CI, 0.72 to 1.62 events) with DOACs. The 5-year cumulative incidence of major bleeding with VKAs was 6.3% (CI, 3.6% to 10.0%). Among patients receiving either a VKA or a DOAC, the incidence of major bleeding was statistically significantly higher among those who were older than 65 years or had creatinine clearance less than 50 mL/min, a history of bleeding, concomitant use of antiplatelet therapy, or a hemoglobin level less than 100 g/L. The case-fatality rate of major bleeding was 8.3% (CI, 5.1% to 12.2%) with VKAs and 9.7% (CI, 3.2% to 19.2%) with DOACs. LIMITATION: Data were insufficient to estimate incidence of major bleeding beyond 1 year of extended anticoagulation with DOACs. CONCLUSION: In patients with a first unprovoked VTE, the long-term risks and consequences of anticoagulant-related major bleeding are considerable. This information will help inform patient prognosis and guide decision making about treatment duration for unprovoked VTE. PRIMARY FUNDING SOURCE: Canadian Institutes of Health Research. (PROSPERO: CRD42019128597).

Aspirin or Rivaroxaban for VTE Prophylaxis after Hip or Knee Arthroplasty.

BACKGROUND: Clinical trials and meta-analyses have suggested that aspirin may be effective for the prevention of venous thromboembolism (proximal deep-vein thrombosis or pulmonary embolism) after total hip or total knee arthroplasty, but comparisons with direct oral anticoagulants are lacking for prophylaxis beyond hospital discharge. METHODS: We performed a multicenter, double-blind, randomized, controlled trial involving patients who were undergoing total hip or knee arthroplasty. All the patients received once-daily oral rivaroxaban (10 mg) until postoperative day 5 and then were randomly assigned to continue rivaroxaban or switch to aspirin (81 mg daily) for an additional 9 days after total knee arthroplasty or for 30 days after total hip arthroplasty. Patients were followed for 90 days for symptomatic venous thromboembolism (the primary effectiveness outcome) and bleeding complications, including major or clinically relevant nonmajor bleeding (the primary safety outcome). RESULTS: A total of 3424 patients (1804 undergoing total hip arthroplasty and 1620 undergoing total knee arthroplasty) were enrolled in the trial. Venous thromboembolism occurred in 11 of 1707 patients (0.64%) in the aspirin group and in 12 of 1717 patients (0.70%) in the rivaroxaban group (difference, 0.06 percentage points; 95% confidence interval [CI], -0.55 to 0.66; P<0.001 for noninferiority and P=0.84 for superiority). Major bleeding complications occurred in 8 patients (0.47%) in the aspirin group and in 5 (0.29%) in the rivaroxaban group (difference, 0.18 percentage points; 95% CI, -0.65 to 0.29; P=0.42). Clinically important bleeding occurred in 22 patients (1.29%) in the aspirin group and in 17 (0.99%) in the rivaroxaban group (difference, 0.30 percentage points; 95% CI, -1.07 to 0.47; P=0.43). CONCLUSIONS: Among patients who received 5 days of rivaroxaban prophylaxis after total hip or total knee arthroplasty, extended prophylaxis with aspirin was not significantly different from rivaroxaban in the prevention of symptomatic venous thromboembolism. (Funded by the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT01720108 .).

Risk of venous thromboembolism in pregnant women with essential thrombocythemia: a systematic review and meta-analysis.

We performed a meta-analysis to evaluate the risk of venous thromboembolism (VTE) in pregnant women with essential thrombocythemia. Twenty-one trials and 756 pregnancies met inclusion criteria. The absolute VTE risk in the antepartum period is not above a threshold where low-molecular-weight heparin (LMWH) prophylaxis is clearly indicated or below a threshold where LMWH should be withheld (2.5%; 95% CI, 1.3-4.3). Postpartum, the absolute VTE risk is above a threshold where postpartum LMWH prophylaxis should be considered (4.4%; 95% CI, 1.2-9.5).

The risk of cesarean delivery after labor induction among women with prior pregnancy complications: a subgroup analysis of the AFFIRM study.

BACKGROUND: To determine the risk of cesarean delivery after labor induction among patients with prior placenta-mediated pregnancy complications (pre-eclampsia, late pregnancy loss, placental abruption or intrauterine growth restriction). METHODS: The AFFIRM database includes patient level data from 9 randomized controlled trials that evaluated the role of LMWH versus no LMWH during pregnancy to prevent recurrent placenta-mediated pregnancy complications. The primary outcome of this sub-study was the proportion of women who had an unplanned cesarean delivery after induction of labor compared to after spontaneous labor. RESULTS: There were 512 patients from 7 randomized trials included in our sub-study. There was no difference in the risk of cesarean delivery between women with labor induction (21/148, 14.2%) and spontaneous labor (79/364, 21.7%) (odds ratio (OR) 0.60, 95% CI, 0.35-1.01; p = 0.052). Among 274 women who used LMWH prophylaxis during pregnancy, the risk of cesarean delivery was lower among those that underwent labor induction (9.8%) compared to spontaneous labor (22.4%) (OR 0.38, 95% CI, 0.17-0.84; p = 0.01). CONCLUSIONS: The risk of cesarean delivery is not increased after labor induction among a higher risk patient population with prior pregnancy complications. Our results suggest that women who receive LMWH during pregnancy might benefit from labor induction.

Screening for Occult Cancer in Unprovoked Venous Thromboembolism.

BACKGROUND: Venous thromboembolism may be the earliest sign of cancer. Currently, there is a great diversity in practices regarding screening for occult cancer in a person who has an unprovoked venous thromboembolism. We sought to assess the efficacy of a screening strategy for occult cancer that included comprehensive computed tomography (CT) of the abdomen and pelvis in patients who had a first unprovoked venous thromboembolism. METHODS: We conducted a multicenter, open-label, randomized, controlled trial in Canada. Patients were randomly assigned to undergo limited occult-cancer screening (basic blood testing, chest radiography, and screening for breast, cervical, and prostate cancer) or limited occult-cancer screening in combination with CT. The primary outcome measure was confirmed cancer that was missed by the screening strategy and detected by the end of the 1-year follow-up period. RESULTS: Of the 854 patients who underwent randomization, 33 (3.9%) had a new diagnosis of occult cancer between randomization and the 1-year follow-up: 14 of the 431 patients (3.2%) in the limited-screening group and 19 of the 423 patients (4.5%) in the limited-screening-plus-CT group (P=0.28). In the primary outcome analysis, 4 occult cancers (29%) were missed by the limited screening strategy, whereas 5 (26%) were missed by the strategy of limited screening plus CT (P=1.0). There was no significant difference between the two study groups in the mean time to a cancer diagnosis (4.2 months in the limited-screening group and 4.0 months in the limited-screening-plus-CT group, P=0.88) or in cancer-related mortality (1.4% and 0.9%, P=0.75). CONCLUSIONS: The prevalence of occult cancer was low among patients with a first unprovoked venous thromboembolism. Routine screening with CT of the abdomen and pelvis did not provide a clinically significant benefit. (Funded by the Heart and Stroke Foundation of Canada; SOME ClinicalTrials.gov number, NCT00773448.).

A meta-analysis of low-molecular-weight heparin to prevent pregnancy loss in women with inherited thrombophilia.

We performed a meta-analysis of randomized controlled trials comparing low-molecular-weight heparin (LMWH) vs no LMWH in women with inherited thrombophilia and prior late (≥10 weeks) or recurrent early (<10 weeks) pregnancy loss. Eight trials and 483 patients met our inclusion criteria. There was no significant difference in livebirth rates with the use of LMWH compared with no LMWH (relative risk, 0.81; 95% confidence interval, 0.55-1.19;P= .28), suggesting no benefit of LMWH in preventing recurrent pregnancy loss in women with inherited thrombophilia.

Are Anti-ß2 Glycoprotein 1 Antibodies Associated with Placenta-Mediated Pregnancy Complications? A Nested Case-Control Study.

BACKGROUND: While anti-ß2 glycoprotein 1 (anti-ß2GP1) antibody positivity is included in the diagnostic criteria for antiphospholipid syndrome (APS), the association between anti-ß2GP1 and the obstetrical complications of APS has been inconsistently reported and remains unclear. OBJECTIVE: We completed a case-control study nested within the Canadian Ottawa and Kingston (OaK) Birth Cohort to evaluate the association between anti-ß2GP1 antibody positivity and placenta-mediated pregnancy complications. STUDY DESIGN: Five hundred cases were randomly selected among pregnant women who experienced any of the following independently adjudicated placenta-mediated pregnancy complications: preeclampsia, placental abruption, late pregnancy loss (≥ 12 weeks' gestation), and birth of a small-for-gestational age (SGA) infant < 10th percentile. Five hundred pregnant women without any placenta-mediated pregnancy complications were selected as controls. Stored blood samples were analyzed for the presence of anti-ß2GP1 antibodies by enzyme-linked immunosorbent assay. RESULTS: Anti-ß2GP1 immunoglobulin G (IgG) and/or immunoglobulin M (IgM) antibodies in titers ≥ 20 G/M units (> 99th percentile) were present in 24 of 497 (4.8%) of controls and 33 of 503 (6.6%) of cases. There was no significant difference between cases and controls for the composite outcome of any placenta-mediated pregnancy complications (odds ratio, 1.38, 95% confidence interval [CI], 0.8-2.37, p = 0.25). CONCLUSION: Our results call into question the association between anti-ß2GP1 antibodies and placenta-mediated pregnancy complications, with further research needed.

Low-molecular-weight heparin and recurrent placenta-mediated pregnancy complications: a meta-analysis of individual patient data from randomised controlled trials.

BACKGROUND: Placenta-mediated pregnancy complications include pre-eclampsia, late pregnancy loss, placental abruption, and birth of a small-for-gestational-age (SGA) neonate. These complications are leading causes of maternal, fetal, and neonatal morbidity and mortality in high-income countries. Affected women are at high risk of recurrence in subsequent pregnancies; however, effective strategies to prevent recurrence are absent. Findings from our previous study-level meta-analysis suggested that low-molecular-weight heparin reduced the risk of recurrent placenta-mediated pregnancy complications. However, we identified significant heterogeneity in the results, possibly due to trial design or inclusion criteria. To identify which patients benefit from, and which outcomes are prevented by, low-molecular-weight heparin, we did an individual patient data meta-analysis. METHODS: We did a systematic review in May, 2013, which identified eight eligible randomised trials done between 2000 and 2013 of low-molecular-weight heparin to prevent recurrent placenta-mediated pregnancy complications. We excluded studies on the basis of the wrong population, the study being ongoing, inability to confirm eligibility of participants, intervention stopped too early, and no response from the principal investigator. We requested individual patient data from the study authors for eligible women (women pregnant at the time of the study with a history of previous pregnancy that had been complicated by one or more of the following: pre-eclampsia, placental abruption, birth of an SGA neonate [<10th percentile], pregnancy loss after 16 weeks' gestation, or two losses after 12 weeks' gestation) and recoded, combined, and analysed the data for our meta-analysis. The primary outcome was a composite of early-onset (<34 weeks) or severe pre-eclampsia, birth of an SGA neonate (<5th percentile), late pregnancy loss (≥20 weeks' gestation), or placental abruption leading to delivery, assessed on an intention-to-treat basis. We assessed risk of bias with the Cochrane Risk of Bias tool. This study is registered with PROSPERO, number CRD42013006249. FINDINGS: We analysed data from 963 eligible women in eight trials: 480 randomly assigned to low-molecular-weight heparin and 483 randomly assigned to no low-molecular-weight heparin. Overall, the risk of bias was not substantial enough to affect decisions regarding trial inclusion. Participants were mostly white (795/905; 88%) with a mean age of 30·9 years (SD 5·0) and 403/963 (42%) had thrombophilia. In the primary analysis, low-molecular-weight heparin did not significantly reduce the risk of recurrent placenta-mediated pregnancy complications (low-molecular-weight heparin 62/444 [14%] versus no low-molecular-weight heparin 95/443 (22%) absolute difference -8%, 95% CI -17·3 to 1·4, p=0·09; relative risk 0·64, 95% CI 0·36-1·11, p=0·11). We noted significant heterogeneity between single-centre and multicentre trials. In subgroup analyses, low-molecular-weight heparin in multicentre trials reduced the primary outcome in women with previous abruption (p=0·006) but not in any of the other subgroups of previous complications. INTERPRETATION: Low-molecular-weight heparin does not seem to reduce the risk of recurrent placenta-mediated pregnancy complications in at-risk women. However, some decreases in event rates might have been too small for the power of our study to explore. FUNDING: Canadian Institutes of Health Research.

Pulmonary Complications of Pregnancy: Venous Thromboembolism.

Unique considerations are needed when diagnosing and treating venous thromboembolism (VTE) in women who are pregnant or postpartum. What are the risks to the fetus, such as drug exposure or the risk of radiation with diagnostic imaging? How does the physiology of pregnancy affect imaging techniques and anticoagulation management? How should anticoagulation be managed around labor and delivery? These questions highlight some of the important considerations needed when managing a pregnant patient with suspected or confirmed VTE. This review outlines what is known about the epidemiology, pathophysiology, clinical risk factors, diagnosis, and therapeutic management of VTE in pregnancy. We also review our preferred diagnostic and treatment algorithm for a pregnant patient with suspected or confirmed VTE.

Meta-analysis of low-molecular-weight heparin to prevent recurrent placenta-mediated pregnancy complications.

A 35-year-old woman with recurrent severe placenta-mediated pregnancy complications in her 2 pregnancies asks: Will low-molecular-weight heparin help prevent recurrent placenta-mediated pregnancy complications in my next pregnancy? We performed a meta-analysis of randomized controlled trials (RCTs) comparing low-molecular-weight heparin (LMWH) vs no LMWH for the prevention of recurrent placenta-mediated pregnancy complications. We identified six RCTs that included a total of 848 pregnant women with prior placenta-mediated pregnancy complications. The primary outcome was a composite of pre-eclampsia (PE), birth of a small-for-gestational-age (SGA) newborn (<10th percentile), placental abruption, or pregnancy loss >20 weeks. Overall, 67 (18.7%) of 358 of women being given prophylactic LMWH had recurrent severe placenta-mediated pregnancy complications compared with 127 (42.9%) of 296 women with no LMWH (relative risk reduction, 0.52; 95% CI, 0.32 to 0.86; P = .01; I(2), 69%, indicating moderate heterogeneity). We identified similar relative risk reductions with LMWH for individual outcomes, including any PE, severe PE, SGA <10th percentile, SGA <5th percentile, preterm delivery <37 weeks, and preterm delivery <34 weeks with minimal heterogeneity. LMWH may be a promising therapy for recurrent, especially severe, placenta-mediated pregnancy complications, but further research is required.

Antepartum dalteparin versus no antepartum dalteparin for the prevention of pregnancy complications in pregnant women with thrombophilia (TIPPS): a multinational open-label randomised trial.

BACKGROUND: Thrombophilias are common disorders that increase the risk of pregnancy-associated venous thromboembolism and pregnancy loss and can also increase the risk of placenta-mediated pregnancy complications (severe pre-eclampsia, small-for-gestational-age infants, and placental abruption). We postulated that antepartum dalteparin would reduce these complications in pregnant women with thrombophilia. METHODS: In this open-label randomised trial undertaken in 36 tertiary care centres in five countries, we enrolled consenting pregnant women with thrombophilia at increased risk of venous thromboembolism or with previous placenta-mediated pregnancy complications. Eligible participants were randomly allocated in a 1:1 ratio to either antepartum prophylactic dose dalteparin (5000 international units once daily up to 20 weeks' gestation, and twice daily thereafter until at least 37 weeks' gestation) or to no antepartum dalteparin (control group). Randomisation was done by a web-based randomisation system, and was stratified by country and gestational age at randomisation day with a permuted block design (block sizes 4 and 8). At randomisation, site pharmacists (or delegates) received a randomisation number and treatment allocation (by fax and/or e-mail) from the central web randomisation system and then dispensed study drug to the local coordinator. Patients and study personnel were not masked to treatment assignment, but the outcome adjudicators were masked. The primary composite outcome was independently adjudicated severe or early-onset pre-eclampsia, small-for-gestational-age infant (birthweight <10th percentile), pregnancy loss, or venous thromboembolism. We did intention-to-treat and on-treatment analyses. This trial is registered with ClinicalTrials.gov, number NCT00967382, and with Current Controlled Trials, number ISRCTN87441504. FINDINGS: Between Feb 28, 2000, and Sept 14, 2012, 292 women consented to participate and were randomly assigned to the two groups. Three women were excluded after randomisation because of ineligibility (two in the antepartum dalteparin group and one in the control group), leaving 146 women assigned to antepartum dalteparin and 143 assigned to no antepartum dalteparin. Some patients crossed over to the other group during treatment, and therefore for on-treatment and safety analysis there were 143 patients in the dalteparin group and 141 in the no dalteparin group. Dalteparin did not reduce the incidence of the primary composite outcome in both intention-to-treat analysis (dalteparin 25/146 [17·1%; 95% CI 11·4-24·2%] vs no dalteparin 27/143 [18·9%; 95% CI 12·8-26·3%]; risk difference -1·8% [95% CI -10·6% to 7·1%)) and on-treatment analysis (dalteparin 28/143 [19·6%] vs no dalteparin 24/141 [17·0%]; risk difference +2·6% [95% CI -6·4 to 11·6%]). In safety analysis, the occurrence of major bleeding did not differ between the two groups. However, minor bleeding was more common in the dalteparin group (28/143 [19·6%]) than in the no dalteparin group (13/141 [9·2%]; risk difference 10·4%, 95% CI 2·3-18·4; p=0·01). INTERPRETATION: Antepartum prophylactic dalteparin does not reduce the occurrence of venous thromboembolism, pregnancy loss, or placenta-mediated pregnancy complications in pregnant women with thrombophilia at high risk of these complications and is associated with an increased risk of minor bleeding. FUNDING: Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, and Pharmacia and UpJohn.

Compression stockings to prevent post-thrombotic syndrome: a randomised placebo-controlled trial.

BACKGROUND: Post-thrombotic syndrome (PTS) is a common and burdensome complication of deep venous thrombosis (DVT). Previous trials suggesting benefit of elastic compression stockings (ECS) to prevent PTS were small, single-centre studies without placebo control. We aimed to assess the efficacy of ECS, compared with placebo stockings, for the prevention of PTS. METHODS: We did a multicentre randomised placebo-controlled trial of active versus placebo ECS used for 2 years to prevent PTS after a first proximal DVT in centres in Canada and the USA. Patients were randomly assigned to study groups with a web-based randomisation system. Patients presenting with a first symptomatic, proximal DVT were potentially eligible to participate. They were excluded if the use of compression stockings was contraindicated, they had an expected lifespan of less than 6 months, geographical inaccessibility precluded return for follow-up visits, they were unable to apply stockings, or they received thrombolytic therapy for the initial treatment of acute DVT. The primary outcome was PTS diagnosed at 6 months or later using Ginsberg's criteria (leg pain and swelling of ≥1 month duration). We used a modified intention to treat Cox regression analysis, supplemented by a prespecified per-protocol analysis of patients who reported frequent use of their allocated treatment. This study is registered with ClinicalTrials.gov, number NCT00143598, and Current Controlled Trials, number ISRCTN71334751. FINDINGS: From 2004 to 2010, 410 patients were randomly assigned to receive active ECS and 396 placebo ECS. The cumulative incidence of PTS was 14·2% in active ECS versus 12·7% in placebo ECS (hazard ratio adjusted for centre 1·13, 95% CI 0·73-1·76; p=0·58). Results were similar in a prespecified per-protocol analysis of patients who reported frequent use of stockings. INTERPRETATION: ECS did not prevent PTS after a first proximal DVT, hence our findings do not support routine wearing of ECS after DVT. FUNDING: Canadian Institutes of Health Research.

Management of pregnancy associated venous-thromboembolism: a survey of practices.

INTRODUCTION: Low-molecular-weight heparin (LMWH) is frequently recommended for the treatment of pregnancy associated venous thromboembolism (PAVTE). Given that prior reports have suggested a wide variation in dosing of LMWH in pregnancy and the use of anti-Xa monitoring in pregnancy, the principal aim of this survey was to assess current practices for the management of PAVTE. METHODS: An electronic survey was conducted. The target sample was members of the North American Society of Obstetric Medicine and Thrombosis Interest Group of Canada. RESULTS: The final sample consisted of 27/69 hematologists (39.1%), 30/69 internists (43.5%), 8/69 obstetricians (11.6%), and 4/69 from other specialties (5.7%). For the acute treatment of patients pregnant patients with deep vein thrombosis 42/69 (60.8%) preferred LMWH given twice a day 42/69 (60.8%), whereas 25/69 (36.2%) preferred once daily. These results were similar for patients with pulmonary embolism (PE). For long-term treatment more than 70% of the respondents favoured treatment with full doses of LMWH given once a day or twice a day and 16/69 (23.2%) intermediate doses for patients diagnosed with DVT. These results were similar for patients with PE. Fourteen physicians out of 69 (20.3%) did not measure anti-Xa monitoring during acute treatment period and 24/69 (34.8%) never used anti-Xa levels during the long term treatment period. Management during the peri-partum period varied widely according to the time of the diagnosis of PAVTE. DISCUSSION: In conclusion, our survey shows wide variation in practice regarding LMWH dosing and anti-Xa monitoring in pregnancy associated VTE and calls for trials comparing different long term strategies using LMWH in patients with PAVTE.