Association between prophylactic low-molecular-weight heparin use in pregnancy and macrosomia: analysis of the Ottawa and Kingston birth cohort

Essentials Low-molecular-weight heparin (LMWH) is used to prevent venous thromboembolism (VTE) in pregnancy. We evaluated the association between LMWH and large for gestational age (LGA) infants. We found no significant associations between LMWH use and LGA. LMWH does not appear to increase the risk for the delivery of an LGA infant. SUMMARY: Background Low-molecular-weight heparin (LMWH), an anticoagulant, is the recommended drug for thromboprophylaxis and treatment of venous thromboembolism (VTE) in pregnancy. During pregnancy, LMWH is routinely prescribed to mothers with an increased risk of VTE or with a history of thrombosis. Although clinical reports of larger offspring born to women administered LMWH have been noted, no studies to date have evaluated or associated the use of LMWH and large for gestational age (LGA) infants. Objectives To determine whether there is an association between LMWH usage in mothers and the prevalence of LGA. Patients/Methods We performed an analysis of the Ottawa and Kingston (OaK) Birth Cohort and report characteristics of LMWH and association LGA (> 10%ile). We used coarsened exact matching (CEM) methods to account for bias and confounding. Results A total of 7519 women from the OaK Birth Cohort were included; 59 were administered LMWH during pregnancy (0.78%). Mothers prescribed LMWH had significantly greater BMI (P = 0.0001), age (P = 0.0001) and parity (P = 0.02). Gestational length was shorter among women administered LMWH compared to those without treatment (37.7 ± 2.0 vs. 39.2 ± 2.0, P < 0.0001), an iatrogenic finding. The odds ratio of an LGA delivery among women administered LMWH was 1.02 (95% confidence interval [CI], 0.48-2.16; P = 0.96) in unadjusted analyses and was 1.15 (95% CI, 0.49-2.71) in the matched sample adjusted for maternal age, BMI and gestational age. Conclusions These results, although exploratory, provide indirect evidence of no increased risk of LGA infants among women prescribed LMWH.

Association between remote major venous thromboembolism risk factors and the risk of recurrence after a first unprovoked episode

Essentials Is remote exposure to major venous thromboembolism (VTE) risk factor related to lower recurrence? We analyzed data from the REVERSE study, a cohort of patients with no recent major risk factor. We found no association between remote risk factors and the risk of recurrence. Patients with remote VTE risk factor should be managed as having had an unprovoked VTE.

SUMMARY

Background It has been shown that the risk of recurrence of venous thromboembolism (VTE) is significantly lower when provoked by a major risk factor such as surgery or trauma compared with an event that was unprovoked. Objectives In this study we aimed to assess the association between remote exposure (3-12 months prior to VTE) to major VTE risk factors and the risk of recurrent VTE. Methods This was a post-hoc analysis of the REVERSE study, a prospective cohort of 646 patients with a first VTE, not provoked by a recent (< 3 months) major risk factor. Results We found no difference in the recurrence rate in patients with or without remote exposure to major VTE risk factors, including immobilization (hazard-ratio [HR], 1.4; 95% confidence interval, 0.7-2.6), surgery (HR, 0.8; 0.3-1.9) and trauma (HR, 1.3; 0.5-3.6). Conclusion None of the tested risk factors were associated with a lower risk of recurrence during follow-up. Patients with remote exposure to major risk factors at the time of a first VTE should not be managed differently from patients with no VTE risk factors.

Net clinical benefit of hospitalization versus outpatient management of patients with acute pulmonary embolism

Essentials Clinical benefit of hospitalization vs. outpatient treatment in pulmonary embolism (PE) is unknown. We performed a propensity matched cohort study of hemodynamically stable PE patients. Regardless of the risk assessment, hospitalized patients had the highest rate of adverse event. If confirmed, ambulatory care of normotensive PE patients may be preferred whenever possible.

SUMMARY

Background The decision to hospitalize or not patients with acute pulmonary embolism (PE) is controversial. Despite the advantages of close monitoring, hospitalization by itself may lead to in-hospital complications and potentially worsen the prognosis of PE patients. Objectives To determine the net clinical benefit of hospitalization vs. outpatient management of normotensive patients with acute pulmonary embolism (PE). Methods Retrospective cohort propensity score analysis (radius marching with replacement). Hemodynamically stable PE patients treated as outpatients or inpatients were matched to balance out differences for 28 patient characteristics and known risk factors for adverse events. The primary outcome was the rate of adverse events at 14 days, including recurrent venous thromboembolism, major bleeding or death. Results Among 1127 eligible patients, 1081 were included in the matched cohort, 576 treated as inpatients and 505 as outpatients. The 14-day rate of adverse events was 13.0% for inpatients and 3.3% for outpatients (adjusted OR, 5.07; 95% CI, 1.68-15.28). The 3-month rate was 21.7% for inpatients and 6.9% for outpatients (OR, 4.90; 95% CI, 2.62-9.17). In the high-risk subgroup (Pulmonary Embolism Severity Index class III-V; n = 597), the 14-day rate of adverse events was 16.5% for hospitalized patients vs. 4.5% for outpatients (OR, 4.16; 95% CI, 1.2-14.35). Conclusion Outpatient treatment of hemodynamically stable PE patients seems to be associated with a lower rate of adverse events than hospitalization and, if confirmed, may be considered as first-line management in patients not requiring specific in-hospital care, regardless of their initial risk stratification, if proper outpatient care can be provided.

A randomised trial of the cool pad pillow topper versus standard care for sleep disturbance and hot flushes in women on endocrine therapy for breast cancer

PURPOSE

Quality of life in women receiving adjuvant endocrine therapy for breast cancer (BC) may be impaired by hot flushes and night sweats. The cool pad pillow topper (CPPT) is a commercial product, promoted to improve quality of sleep disrupted by hot flushes. This study aimed to identify if the CPPT reduces severity of sleep disturbance by minimising effects of hot flushes.

METHODS

This randomised phase II trial, recruited women with BC, on adjuvant endocrine therapy, experiencing hot flushes and insomnia. Participants were randomised (stratified by baseline sleep efficiency score (SES) and menopausal status) to the intervention arm (CPPT + standard care) or control arm (standard care). Participants completed Hospital Anxiety and Depression Scale and Functional Assessment of Cancer Therapy-Breast (FACT-B) questionnaires and fortnightly sleep/hot flush diaries (where responses were averaged over 2-week periods). The primary endpoint was change in average SES from -2 to 0 weeks to 2 to 4 weeks.

RESULTS

Seventy-four pre- (68.9 %) and post-menopausal (31.1 %) women were recruited. Median age was 49.5 years. Endocrine therapies included tamoxifen (93.2 %). Median SES at weeks 2 to 4 improved in both arms but the increase on the intervention arm was almost twice that on the control arm (p = 0.024). There were significantly greater reductions in hot flushes and HADS depression in the intervention arm (p = 0.09 and p = 0.036, respectively). There were no significant differences in FACT-B or HADS anxiety.

CONCLUSION

This study supports the use of the CPPT as an aid to reduce sleep disturbance and the frequency/severity of hot flushes.

Interobserver reliability of compression ultrasound for residual thrombosis after first unprovoked deep vein thrombosis

BACKGROUND

Accurate assessment of residual thrombosis is of clinical importance for diagnostic baseline imaging, and may be of value in risk stratification for recurrent venous thromboembolism (VTE). This study evaluated the interobserver reliability of the measurement of residual thrombosis in patients 6 months after a first unprovoked deep vein thrombosis (DVT) of the leg.

PATIENTS/METHODS

All enrolled patients received two ultrasound examinations by two independent blinded ultrasound technicians 5-7 months after their first unprovoked DVT. In total, 49 patients completed the two baseline ultrasound examinations. During the examinations, the presence of residual thrombosis was evaluated. If residual thrombosis was present, a detailed description of the size and location was reported. After all ultrasound results had been collected, the interobserver agreement was calculated by use of the kappa statistics, Pearson correlation, and the Bland-Altman plot. Furthermore, the clinical implications of interobserver reliability were examined.

RESULTS

The interobserver reliability of the assessment of whether residual thrombosis is present was very good (κ = 0.92). The interobserver reliability of the measurement of residual thrombosis was good (r2 = 0.648), with a limited number of patients being misclassified. For the assessment of the percentage of residual occlusion, the interobserver reliability was fair (r2 = 0.357).

CONCLUSIONS

Our results suggest that the interobserver reliability for measurement of residual thrombosis is high, and that the variability introduced by interobserver reliability has minimal clinical implications. Our study is important for the use of baseline imaging for the diagnostic and prognostic management of recurrent VTE.

Excessive gestational weight gain predicts large for gestational age neonates independent of maternal body mass index

OBJECTIVE

To determine the effects of maternal pre-pregnancy body mass index (BMI) and gestational weight gain (GWG) on large-for-gestational-age (LGA) birth weight (≥90th % ile).

METHODS

We examined 4321 mother-infant pairs from the Ottawa and Kingston (OaK) birth cohort. Multivariate logistic regression (controlling for gestational and maternal age, pre-pregnancy weight, parity, smoking) were performed and odds ratios (ORs) calculated.

RESULTS

Prior to pregnancy, a total of 23.7% of women were overweight and 16.2% obese. Only 29.3% of women met GWG targets recommended by the Institute of Medicine (IOM), whereas 57.7% exceeded the guidelines. Adjusting for smoking, parity, age, maternal height, and achieving the IOM's recommended GWG, overweight (OR 1.99; 95%CI 1.17-3.37) or obese (OR 2.64; 95% CI 1.59-4.39) pre-pregnancy was associated with a higher rate of LGA compared to women with normal BMI. In the same model, exceeding GWG guidelines was associated with higher rates of LGA (OR 2.86; 95% CI 2.09-3.92), as was parity (OR 1.49; 95% CI 1.22-1.82). Smoking (OR 0.53; 95%CI 0.35-0.79) was associated with decreased rates of LGA. The adjusted association with LGA was also estimated for women who exceeded the GWG guidelines and were overweight (OR 3.59; 95% CI 2.60-4.95) or obese (OR 6.71; 95% CI 4.83-9.31).

CONCLUSION

Pregravid overweight or obesity and gaining in excess of the IOM 2009 GWG guidelines strongly increase a woman's chance of having a larger baby. Lifestyle interventions that aim to optimize GWG by incorporating healthy eating and exercise strategies during pregnancy should be investigated to determine their effects on LGA neonates and down-stream child obesity.

Residual vein obstruction as a predictor for recurrent thromboembolic events after a first unprovoked episode: data from the REVERSE cohort study

OBJECTIVES

There is growing interest in using residual vein obstruction (RVO) to guide the duration of oral anticoagulant therapy (OAT) for unprovoked deep vein thrombosis (DVT). We sought to determine if RVO as determined by compression ultrasonography (CUS) after completion of 5-7 months of anticoagulation for unprovoked DVT is associated with an increased risk of recurrent venous thromboembolism (VTE).

MATERIALS AND METHODS

This was a multicentre multinational prospective cohort study undertaken in tertiary care centers. Patients with a first 'unprovoked' major VTE were enrolled over a 4-year period and completed a mean 18-month follow-up in September 2006. All 452 patients with DVT had baseline CUS at inclusion to assess any RVO before stopping OAT at 5-7 months. During follow-up off OAT, all episodes of suspected recurrent VTE were independently adjudicated with reference to baseline imaging.

RESULTS

Forty-five out of 231 patients with abnormal CUS (19.5%) had recurrent VTE during follow-up, as compared with 32 out of 220 patients with normal CUS (14.6%), and one patient had inadequate CUS. There was no significant association between an abnormal CUS at inclusion and the risk of recurrent VTE: hazard ratio 1.4 (95% confidence interval, 0.9-2.1), P=0.19. None of the different degrees of clot resolution on baseline CUS was statistically significantly associated with the risk of recurrent VTE.

CONCLUSION

In our study, the presence of RVO at the time of OAT withdrawal was not associated with a statistically significant higher risk of recurrent VTE. RVO assessment may not be useful to guide duration of anticoagulation.

Safety of outpatient treatment in acute pulmonary embolism

INTRODUCTION

Data regarding outpatient treatment of pulmonary embolism (PE) is scarce. This study evaluates the safety of outpatient management of acute PE.

METHODS

This is a retrospective cohort study of consecutive patients presenting at the Ottawa Hospital with acute PE diagnosed between 1 January 2007 and 31 December 2008. PE was defined as an arterial filling defect on CTPA or a high probability V/Q scan. Patients were managed as outpatients if they were hemodynamically stable, did not require supplemental oxygenation and did not have contraindications to low-molecular-weight heparin therapy.

RESULTS

In this cohort of 473 patients with acute PE, 260 (55.0%) were treated as outpatients and 213 (45.0%) were admitted to the hospital. The majority of the patients were admitted because of severe comorbidities (45.5%) or hypoxia (22.1%). No outpatient died of fatal PE during the 3-month follow-up period. At the end of follow-up, the overall mortality was 5.0% (95% CI, 2.7-8.4%). The rates of recurrent venous thromboembolism (VTE) in outpatients were 0.4% (95% CI, 0.0-2.1%) and 3.8% (95% CI, 1.9-7.0%) within 14 days and 3 months, respectively. The rates of major bleeding episodes were 0% (95% CI, 0-1.4%) and 1.5% (95% CI, 0.4-3.9%) within 14 days and 3 months, respectively. Four (1.5%) outpatients were admitted to the hospital within 14 days.

CONCLUSIONS

A majority of patients with acute PE can be managed as outpatients with a low risk of mortality, recurrent VTE and major bleeding episodes.

D-dimer testing in pregnant patients: towards determining the next 'level' in the diagnosis of deep vein thrombosis

SUMMARY BACKGROUND

The role of D-dimer in excluding deep vein thrombosis (DVT) in pregnancy is currently uncertain. We hypothesized that the specificity of sensitive D-dimer assays could be improved without compromising sensitivity by using higher D-dimer cut-off values.

OBJECTIVE

To determine the test characteristics of two rapid enzyme-linked immunosorbent assays and three latex agglutination assays in pregnancy.

METHOD

We recruited consecutive pregnant women who presented to participating centers with suspected DVT for the study. Symptomatic women were investigated with compression ultrasonography, and received 3 months of clinical follow-up to assess for the presence of venous thrombosis. Plasma samples for D-dimer were collected and frozen at the time of presentation. The median and mean D-dimer values for respective trimesters of pregnancy in patients with and without DVT were calculated. Receiver operating curves (ROCs) were plotted for respective assays to establish the best cut-points. The test characteristics corresponding to standard cut-points and these 'pregnancy' cut-points are presented.

RESULTS

The prevalence of DVT in our cohort was 6.6% (95% confidence interval 4.0-10.6%). The mean and median D-dimer values were significantly increased throughout pregnancy. Overall, women with confirmed DVT had higher D-dimer levels than women without DVT (P < 0.0001). Improved specificities (62-79%) were observed with the use of higher cut-points obtained from ROCs for all five assays, and high sensitivities were maintained (80-100%) for DVT diagnosis.

CONCLUSION

Using higher cut-points than those used in non-pregnant patients, the specificity of D-dimer assays for the diagnosis of DVT in pregnancy can be improved without compromising sensitivity. Validation in prospective management studies is needed.

Prediction of the warfarin maintenance dose after completion of the 10 mg initiation nomogram: do we really need genotyping?

INTRODUCTION

Initiation of warfarin therapy is complicated by its narrow therapeutic index and inter-patient dose-effect variability. A '10-mg nomogram' warfarin initiation protocol permits safe therapeutic anticoagulation in outpatients started on warfarin. We aimed to develop a safe and effective warfarin maintenance dose prediction tool in these patients.

METHODS

Baseline potential predictor variables were collected on a retrospective cohort of outpatients initiated on warfarin for venous thromboembolism treatment. The primary outcome was the warfarin maintenance dose, defined as mean warfarin dose over the last 10 days of the first month of warfarin treatment. Univariate and multivariate analyses were performed to determine which baseline variables were warfarin maintenance dose predictors. An independent cohort of patients validated the derived warfarin maintenance dose prediction rule.

RESULTS

Patient's age and weight, cumulative dose of warfarin over the first week of induction and international normalized ratio (INR) on days 3, 5 and 8 were statistically significant predictors of the warfarin maintenance dose. Our final prediction rule reads: maintenance dose (in mg) = 2.5 + 10% of the first week cumulative dose - INR value at day 8 + 1.5 if INR was below 2.0 at day 5. In the validation cohort, the predicted dose was strongly correlated with the actual maintenance dose (r = 0.88, P < 0.0001). The mean difference between observed and predicted dose was not clinically significant: -0.1 +/- 1.1 mg.

CONCLUSION

In outpatients initiated on warfarin using a '10-mg nomogram', a simple prediction rule can accurately predict warfarin maintenance dose. Prospective studies employing the rule are indicated.

Validation of a diagnostic approach to exclude recurrent venous thromboembolism

SUMMARY INTRODUCTION

The diagnosis of recurrent venous thromboembolism (VTE) is a challenge in clinical practice. Our objective was to evaluate the safety of a diagnostic strategy utilizing comparison of diagnostic test results with baseline imaging results to rule out suspected recurrent VTE.

METHODS

The REVERSE study was a prospective cohort study whose primary aim was to develop a clinical prediction rule for recurrent VTE. We included and followed patients who completed 5-7 months of anticoagulant therapy after a first unprovoked VTE. Suspected cases of recurrent VTE were assessed according to standardized diagnostic criteria based on comparison of diagnostic test results with those obtained at the time of anticoagulant treatment withdrawal.

RESULTS

Out of the 398 suspected events, a recurrent VTE was diagnosed in 106 cases (26.6%) and excluded in 292 cases. In 76 cases (19%), the diagnosis of recurrent VTE was excluded on the basis of the fact that no significant change on diagnostic imaging was detected when compared to baseline imaging. During the ensuing 3 months, six patients received anticoagulant therapy after recurrent VTE was excluded, and two were lost to follow-up. Eight of 284 remaining patients in whom recurrent VTE had been excluded, who were not treated and who were not lost to follow-up were diagnosed with subsequent VTE (3-month risk, 2.8%; 95% confidence interval, 1.4-5.5%). Six of these eight patients with subsequent recurrent VTE had a known superficial or distal thrombosis at the time of initial suspected recurrent VTE.

CONCLUSION

A diagnostic strategy comparing diagnostic test results obtained at the time of the suspected recurrent event with those obtained at baseline can safely and effectively rule out recurrent VTE in a significant proportion of patients. Registered at http://www.clinicaltrials.gov identifier: NCT00261014.

Dose escalation of low molecular weight heparin to manage recurrent venous thromboembolic events despite systemic anticoagulation in cancer patients

SUMMARY BACKGROUND

Cancer patients with venous thromboembolism (VTE) are at high risk of recurrent VTE despite standard anticoagulation. To date, very little published literature is available to guide the treatment of cancer patients with recurrent VTE.

OBJECTIVES

To evaluate the benefit and risk of low molecular weight heparin (LMWH) dose escalation in cancer patients with recurrent VTE.

PATIENTS AND METHODS

This was a retrospective cohort study of consecutive cancer outpatients referred for management of a symptomatic, recurrent VTE while receiving an anticoagulant. Confirmed episodes of recurrent VTE were treated with either dose escalation of LMWH in patients already anticoagulated with LMWH, or initiation of therapeutic dose LMWH in patients who were taking a vitamin K antagonist (VKA). All patients were followed for a minimum of 3 months after the index recurrent VTE unless they died during this period.

RESULTS

Seventy cancer patients with a recurrent VTE despite ongoing anticoagulation were included. At the time of the recurrence, 67% of patients were receiving LMWH, and 33% were receiving a VKA. A total of six patients [8.6%; 95% confidence interval (CI) 4.0-17.5%] had a second recurrent VTE during the 3-month follow-up period, at an event rate of 9.9 per 100 patient-years (95% CI 2.0-17.8%). Three patients (4.3%; 95% CI 1.5-11.9%), or 4.8 per 100 patient-years (95% CI 0.0-10.3%) of follow-up, had bleeding complications. The median time between the index recurrent VTE to death was 11.4 months (range, 0-83.9 months).

CONCLUSIONS

Cancer patients with recurrent VTE have a short median survival. Escalating the dose of LMWH can be effective for treating cases that are resistant to standard, weight-adjusted doses of LMWH or a VKA.

Dalteparin for the prevention of recurrence of placental-mediated complications of pregnancy in women without thrombophilia: a pilot randomized controlled trial

BACKGROUND

The role of anticoagulants for the prevention of placental-mediated pregnancy complications is uncertain.

OBJECTIVES

Our aim was to investigate the effectiveness of dalteparin, a low-molecular-weight heparin, in preventing the recurrence of these complications in women without thrombophilia.

PATIENTS/METHODS

Between August 1 2000 and June 20 2007, 116 pregnant women with: (i)

RESULTS

Among the 110 women included in the final analysis, dalteparin was associated with a lower rate of the primary outcome [5.5% (n = 3/55) vs. 23.6% (n = 13/55), adjusted odds ratio (OR) 0.15, 95% confidence interval (CI) 0.03-0.70]. Secondary outcomes were not statistically different between the groups. Bleeding problems or thrombocytopenia did not occur.

CONCLUSION

In this pilot study, dalteparin is effective in decreasing the recurrence of placental-mediated complications in women without thrombophilia. Our results require confirmation in further randomized trials.

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MESH Headings

• Adult
• Dalteparin/adverse effects
• Dalteparin/therapeutic use
• Female
• Fetal Death
• Humans
• Infant, Low Birth Weight
• Infant, Newborn
• Pilot Projects
• Placenta/physiopathology
• Pre-Eclampsia/prevention & control
• Pregnancy
• Pregnancy Complications/drug therapy
• Pregnancy Complications/prevention & control
• Pregnancy Outcome
• Secondary Prevention

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Grants Collapse

Affiliation(s)

E Rey Division of Obstetrics Medicine, Department of Obstetrics and Gynaecology, CHU Sainte-Justine, Montreal, QC, Canada.
P Garneau
M David
R Gauthier
L Leduc
N Michon
F Morin
C Demers
S R Kahn
L A Magee
M Rodger

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A pilot study of central venous catheter survival in cancer patients using low-molecular-weight heparin (dalteparin) and warfarin without catheter removal for the treatment of upper extremity deep vein thrombosis (The Catheter Study)

BACKGROUND

Central venous catheters in patients with cancer are associated with development of deep vein thrombosis (DVT); however, there is no accepted standard treatment.

OBJECTIVES

To assess the safety and effectiveness of a management strategy for central venous catheter-related DVT in cancer patients consisting of dalteparin and warfarin without the need for line removal.

PATIENTS/METHODS

Patients older than 18 years of age with an active malignancy and who had symptomatic, acute, objectively documented UEDVT were eligible. Patients were treated with dalteparin 200 IU kg(-1) per day for 5-7 days and warfarin with a target International Normalized Ratio of 2.0-3.0. Patients were followed for 3 months for recurrent venous thromboembolism, major hemorrhage and survival of the central venous catheter.

RESULTS

There were 74 patients (48 males). The average age was 58 years. There were no episodes of recurrent venous thromboembolism and three (4%) major bleeds. No lines were removed because of infusion failure or recurrence/extension of DVT.

CONCLUSION

Treatment of UEDVTs secondary to central catheters in cancer patients with standard dalteparin/warfarin can allow the central line to remain in situ with little risk of line failure or recurrence/extension of the DVT.

Predictors of the post-thrombotic syndrome during long-term treatment of proximal deep vein thrombosis

BACKGROUND

The post-thrombotic syndrome is a chronic, poorly understood complication of deep venous thrombosis (DVT).

OBJECTIVES

To evaluate predictors of the post-thrombotic syndrome, including intensity of long-term anticoagulation, and to assess the impact of the post-thrombotic syndrome on quality of life.

PATIENTS AND METHODS

The setting was 13 Canadian hospitals and one US hospital. One hundred and forty-five patients with an unprovoked episode of proximal DVT who were initially treated with 3 months of conventional-intensity warfarin [target International Normalized Ratio (INR) of 2.5] then participated in a trial comparing two intensities of long-term warfarin therapy (target INR 2.5 vs. INR 1.7). Post-thrombotic syndrome was assessed at the end of the trial using a validated clinical scale. Generic and venous disease-specific quality of life was compared in patients with and without the post-thrombotic syndrome. Multivariable regression analyses were performed to identify predictors of the post-thrombotic syndrome and of its severity.

RESULTS

After an average follow-up of 2.2 years, the prevalence of post-thrombotic syndrome was 37% and of severe post-thrombotic syndrome was 4%. Quality of life was worse in patients with the post-thrombotic syndrome compared with patients who did not have it. The presence of factor (F)V Leiden or the prothrombin gene mutation was an independent predictor of both a lower risk (P = 0.006) and reduced severity (P = 0.045) of the post-thrombotic syndrome. Intensity of anticoagulation did not influence the risk of developing the post-thrombotic syndrome.

CONCLUSIONS

The post-thrombotic syndrome is a frequent and burdensome complication of proximal DVT, even among patients maintained on long-term oral anticoagulation. While the presence of FV Leiden or prothrombin gene mutation appears to be associated with a reduced risk of post-thrombotic syndrome, this finding requires further evaluation in prospective studies.

Single-Arm Study of Bridging Therapy With Low-Molecular-Weight Heparin for Patients at Risk of Arterial Embolism Who Require Temporary Interruption of Warfarin

Background— When warfarin is interrupted for surgery, low-molecular-weight heparin is often used as bridging therapy. However, this practice has never been evaluated in a large prospective study. This study was designed to assess the efficacy and safety of bridging therapy with low-molecular-weight heparin initiated out of hospital.

Methods and Results— This was a prospective, multicenter, single-arm cohort study of patients at high risk of arterial embolism (prosthetic valves and atrial fibrillation with a major risk factor). Warfarin was held for 5 days preoperatively. Low-molecular-weight heparin was given 3 days preoperatively and at least 4 days postoperatively. Patients were followed up for 3 months for thromboembolism and bleeding. Eleven Canadian tertiary care academic centers participated; 224 patients were enrolled. Eight patients (3.6%; 95% CI, 1.8 to 6.9) had an episode of thromboembolism, of which 2 (0.9%; 95% CI, 0.2 to 3.2) were judged to be due to cardioembolism. Of these 8 episodes of thromboembolism, 6 occurred in patients who had warfarin deferred or withdrawn because of bleeding. There were 15 episodes of major bleeding (6.7%; 95% CI, 4.1 to 10.8): 8 occurred intraoperatively or early postoperatively before low-molecular-weight heparin was restarted, 5 occurred in the first postoperative week after low-molecular-weight heparin was restarted, and 2 occurred well after low-molecular-weight heparin was stopped. There were no deaths.

Conclusions— Bridging therapy with subcutaneous low-molecular-weight heparin is feasible; however, the optimal approach for the management of patients who require temporary interruption of warfarin to have invasive procedures is uncertain.

Diagnosis of pulmonary embolism

Pulmonary embolism (PE) is a common, lethal yet treatable disease. The clinical diagnosis of PE remains to be a problem due to the nonspecific presenting signs, symptoms, electrocardiographic findings, arterial blood gas abnormalities and chest X-ray changes. Despite these nonspecific clinical findings, clinicians are adept at assigning pretest probability using overall clinical assessment. Clinical models have been developed to improve the accuracy of pretest probability assessment. D-dimers are becoming a widely available clinical tool useful in the diagnostic management of suspected PE. The limitations of the imaging modalities for PE [ventilation-perfusion (V/Q) scanning, spiral computerised tomography, pulmonary angiography and venous leg imaging] necessitate the use of these tests in series and in combination with clinical pretest probability assessment and D-dimer in diagnostic management algorithms. These algorithms permit safe diagnostic management of patients with suspected PE while limiting invasiveness, inaccessibility and expense.

Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer

BACKGROUND

The limitations of the current diagnostic standard, ventilation-perfusion lung scanning, complicate the management of patients with suspected pulmonary embolism. We previously demonstrated that determining the pretest probability can assist with management and that the high negative predictive value of certain D -dimer assays may simplify the diagnostic process.

OBJECTIVE

To determine the safety of using a simple clinical model combined with D -dimer assay to manage patients presenting to the emergency department with suspected pulmonary embolism.

DESIGN

Prospective cohort study.

SETTING

Emergency departments at four tertiary care hospitals in Canada.

PATIENTS

930 consecutive patients with suspected pulmonary embolism.

INTERVENTIONS

Physicians first used a clinical model to determine patients' pretest probability of pulmonary embolism and then performed a D -dimer test. Patients with low pretest probability and a negative D -dimer result had no further tests and were considered to have a diagnosis of pulmonary embolism excluded. All other patients underwent ventilation-perfusion lung scanning. If the scan was nondiagnostic, bilateral deep venous ultrasonography was done. Whether further testing (by serial ultrasonography or angiography) was done depended on the patients' pretest probability and the lung scanning results.

MEASUREMENTS

Patients received a diagnosis of pulmonary embolism if they had a high-probability ventilation-perfusion scan, an abnormal result on ultrasonography or pulmonary angiography, or a venous thromboembolic event during follow-up. Patients for whom the diagnosis was considered excluded were followed up for 3 months for the development of thromboembolic events.

RESULTS

The pretest probability of pulmonary embolism was low, moderate, and high in 527, 339, and 64 patients (1.3%, 16.2%, and 37.5% had pulmonary embolism), respectively. Of 849 patients in whom a diagnosis of pulmonary-embolism had initially been excluded, 5 (0.6% [95% CI, 0.2% to 1.4%]) developed pulmonary embolism or deep venous thrombosis during follow-up. However, 4 of these patients had not undergone the proper diagnostic testing protocol. In 7 of the patients who received a diagnosis of pulmonary embolism, the physician had performed more diagnostic tests than were called for by the algorithm. In 759 of the 849 patients in whom pulmonary embolism was not found on initial evaluation, the diagnostic protocol was followed correctly. Only 1 (0.1% [CI, 0.0% to 0.7%]) of these 759 patients developed thromboembolic events during follow-up. Of the 437 patients with a negative D -dimer result and low clinical probability, only 1 developed pulmonary embolism during follow-up; thus, the negative predictive value for the combined strategy of using the clinical model with D -dimer testing in these patients was 99.5% (CI, 99.1% to 100%).

CONCLUSION

Managing patients for suspected pulmonary embolism on the basis of pretest probability and D -dimer result is safe and decreases the need for diagnostic imaging.

Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer

BACKGROUND

The limitations of the current diagnostic standard, ventilation-perfusion lung scanning, complicate the management of patients with suspected pulmonary embolism. We previously demonstrated that determining the pretest probability can assist with management and that the high negative predictive value of certain D -dimer assays may simplify the diagnostic process.

OBJECTIVE

To determine the safety of using a simple clinical model combined with D -dimer assay to manage patients presenting to the emergency department with suspected pulmonary embolism.

DESIGN

Prospective cohort study.

SETTING

Emergency departments at four tertiary care hospitals in Canada.

PATIENTS

930 consecutive patients with suspected pulmonary embolism.

INTERVENTIONS

Physicians first used a clinical model to determine patients' pretest probability of pulmonary embolism and then performed a D -dimer test. Patients with low pretest probability and a negative D -dimer result had no further tests and were considered to have a diagnosis of pulmonary embolism excluded. All other patients underwent ventilation-perfusion lung scanning. If the scan was nondiagnostic, bilateral deep venous ultrasonography was done. Whether further testing (by serial ultrasonography or angiography) was done depended on the patients' pretest probability and the lung scanning results.

MEASUREMENTS

Patients received a diagnosis of pulmonary embolism if they had a high-probability ventilation-perfusion scan, an abnormal result on ultrasonography or pulmonary angiography, or a venous thromboembolic event during follow-up. Patients for whom the diagnosis was considered excluded were followed up for 3 months for the development of thromboembolic events.

RESULTS

The pretest probability of pulmonary embolism was low, moderate, and high in 527, 339, and 64 patients (1.3%, 16.2%, and 37.5% had pulmonary embolism), respectively. Of 849 patients in whom a diagnosis of pulmonary-embolism had initially been excluded, 5 (0.6% [95% CI, 0.2% to 1.4%]) developed pulmonary embolism or deep venous thrombosis during follow-up. However, 4 of these patients had not undergone the proper diagnostic testing protocol. In 7 of the patients who received a diagnosis of pulmonary embolism, the physician had performed more diagnostic tests than were called for by the algorithm. In 759 of the 849 patients in whom pulmonary embolism was not found on initial evaluation, the diagnostic protocol was followed correctly. Only 1 (0.1% [CI, 0.0% to 0.7%]) of these 759 patients developed thromboembolic events during follow-up. Of the 437 patients with a negative D -dimer result and low clinical probability, only 1 developed pulmonary embolism during follow-up; thus, the negative predictive value for the combined strategy of using the clinical model with D -dimer testing in these patients was 99.5% (CI, 99.1% to 100%).

CONCLUSION

Managing patients for suspected pulmonary embolism on the basis of pretest probability and D -dimer result is safe and decreases the need for diagnostic imaging.

Diagnostic value of the electrocardiogram in suspected pulmonary embolism

The electrocardiogram is shown to be of limited diagnostic value for determining pulmonary embolism in a prospective cohort study of unselected patients with suspected pulmonary embolism.

Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer

We have previously demonstrated that a clinical model can be safely used in a management strategy in patients with suspected pulmonary embolism (PE). We sought to simplify the clinical model and determine a scoring system, that when combined with D-dimer results, would safely exclude PE without the need for other tests, in a large proportion of patients. We used a randomly selected sample of 80% of the patients that participated in a prospective cohort study of patients with suspected PE to perform a logistic regression analysis on 40 clinical variables to create a simple clinical prediction rule. Cut points on the new rule were determined to create two scoring systems. In the first scoring system patients were classified as having low, moderate and high probability of PE with the proportions being similar to those determined in our original study. The second system was designed to create two categories, PE likely and unlikely. The goal in the latter was that PE unlikely patients with a negative D-dimer result would have PE in less than 2% of cases. The proportion of patients with PE in each category was determined overall and according to a positive or negative SimpliRED D-dimer result. After these determinations we applied the models to the remaining 20% of patients as a validation of the results. The following seven variables and assigned scores (in brackets) were included in the clinical prediction rule: Clinical symptoms of DVT (3.0), no alternative diagnosis (3.0), heart rate >100 (1.5), immobilization or surgery in the previous four weeks (1.5), previous DVT/PE (1.5), hemoptysis (1.0) and malignancy (1.0). Patients were considered low probability if the score was <2.0, moderate of the score was 2.0 to 6.0 and high if the score was over 6.0. Pulmonary embolism unlikely was assigned to patients with scores < or =4.0 and PE likely if the score was >4.0. 7.8% of patients with scores of less than or equal to 4 had PE but if the D-dimer was negative in these patients the rate of PE was only 2.2% (95% CI = 1.0% to 4.0%) in the derivation set and 1.7% in the validation set. Importantly this combination occurred in 46% of our study patients. A score of <2.0 and a negative D-dimer results in a PE rate of 1.5% (95% CI = 0.4% to 3.7%) in the derivation set and 2.7% (95% CI = 0.3% to 9.0%) in the validation set and only occurred in 29% of patients. The combination of a score < or =4.0 by our simple clinical prediction rule and a negative SimpliRED D-Dimer result may safely exclude PE in a large proportion of patients with suspected PE.

Cost-effectiveness of low-molecular-weight heparin and unfractionated heparin in treatment of deep vein thrombosis

BACKGROUND

Acute deep vein thrombosis has traditionally been treated with unfractionated heparin (UFH), administered intravenously, but low-molecular-weight heparins (LMWH), administered subcutaneously, have recently become available. The authors sought to determine which therapy was more cost-effective for inpatient and outpatient treatment of deep vein thrombosis.

METHODS

An incremental cost-effectiveness analysis based on a decision tree was performed for 4 treatment strategies for deep vein thrombosis. Rate of major hemorrhage while receiving heparin, rate of recurrence of venous thromboembolism 3 months after treatment and mortality rate 3 months after treatment were determined by meta-analysis. Costs for the UFH therapy were prospectively collected by a case-costing accounting system for 105 patients with deep vein thrombosis treated in fiscal year 1995/96. The costs for LMWH therapy were modelled, and cost-effectiveness was determined by decision analysis.

RESULTS

Meta-analysis revealed a mean difference in risk of hemorrhage of -1.1% (95% confidence interval [CI] -2.4% to 0.3%), a mean difference in risk of recurrence of venous thromboembolism of -2.6% (95% CI -4.5% to -0.7%) and a mean difference in risk of death of -1.9% (95% CI -3.6% to -0.4%), all in favour of subcutaneous unmonitored administration of LMWH. The cost to treat one inpatient was $2993 for LMWH and $3048 for UFH. Even more would be saved if LMWH was delivered on an outpatient basis (cost of $1641 per patient). The cost-effectiveness analysis showed that LMWH in any treatment setting is more cost effective than UFH. A sensitivity analysis demonstrated the robustness of this conclusion.

INTERPRETATION

Treatment of deep vein thrombosis with LMWH is more cost effective than treatment with UFH in both inpatient and outpatient settings.

Morphological and molecular characteristics of living human fetuses between Carnegie stages 7 and 23: ultrasound scanning and direct measurements

The developmental age of an embryo in the first trimester of pregnancy is generally determined by ultrasound scanning and/or by calculation from menstrual age. In the original studies, validation of the estimate of gestational age by ultrasound was not possible as the exact date of conception was unknown. Variation in growth rates of identically aged fetuses has previously been reported after assisted conception and with the use of ultrasound scanning. As these pregnancies were ongoing the accuracy of the scanning results could not be determined. Comparison of scanning and direct measurements after termination of pregnancy and menstrual age were carried out to determine the accuracy in fetal dating. The results suggest that the use of ultrasound scanning to determine gestational age is of less use than previously thought, and that the use of menstrual age is severely limited.

Restriction endonuclease analysis of DNA from two isolates of Chlamydia psittaci obtained from human abortions

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Thoracic duct-to-pulmonary vein shunt in the treatment of experimental right heart failure

Elevated venous pressure in right heart failure leads not only to an increase in lymph formation but also to progressive resistance in the neck to the return of lymph to the circulation via the thoracic duct. Sequestration of fluid behind the failing heart tends to protect the circulation but at the same time leads to the clinical manifestations of heart failure.

The present study was performed on 40 dogs with combined tricuspid insufficiency and pulmonary stenosis. Thoracic duct lymph flow was greatly increased. Pressure was considerably greater in the systemic veins than in the pulmonary vein beyond the right heart obstruction. Lymph flow was substantially enhanced when the thoracic duct was connected to the lower pressure pulmonary veins. Furthermore, direct anastomosis of the thoracic duct to the pulmonary vein resulted in fall in systemic venous pressure, increase in renal excretion of salt and water, and reduction in ascites. These results indicate that alterations in the flow of thoracic duct lymph have important bearing on the manifestations and treatment of right heart failure.