Alfonso Iorio

Enoxaparin plus compression stockings compared with compression stockings alone in the prevention of venous thromboembolism after elective neurosurgery.

Background Compression stockings are recommended for prophylaxis against venous thromboembolism in patients undergoing neurosurgery, but anticoagulant agents have not gained wide acceptance because of concern about intracranial bleeding. Methods In a multicenter, randomized, double-blind trial, we assessed the efficacy and safety of enoxaparin in conjunction with the use of compression stockings in the prevention of venous thromboembolism in patients undergoing elective neurosurgery. Enoxaparin (40 mg once daily) or placebo was given subcutaneously for not less than seven days beginning within 24 hours after surgery. The primary end point was symptomatic, objectively confirmed venous thromboembolism or deep-vein thrombosis assessed by bilateral venography, which was performed in all patients on day 8±1. Bleeding side effects were carefully assessed. Results Among the 307 patients assigned to treatment groups, 129 of the 154 patients receiving placebo (84 percent) and 130 of the 153 patients receiving enoxaparin (85 percent) had venographic studies adequate for analysis. An additional patient in the placebo group died before venography of autopsyconfirmed pulmonary embolism. In this analysis, 42 patients given placebo (32 percent) and 22 patients given enoxaparin (17 percent) had deep-vein thrombosis (relative risk in the enoxaparin group, 0.52; 95 percent confidence interval, 0.33 to 0.82; P=0.004). The rates of proximal deep-vein thrombosis were 13 percent in patients receiving placebo and 5 percent in patients receiving enoxaparin (relative risk in the enoxaparin group, 0.41; 95 percent confidence interval, 0.17 to 0.95; P=0.04). Two patients in the placebo group died of autopsy-confirmed pulmonary embolism on days 9 and 16. Major bleeding occurred in four patients receiving placebo (intracranial bleeding in all four) and four patients (intracranial bleeding in three) receiving enoxaparin (3 percent of each group). Conclusions Enoxaparin combined with compression stockings is more effective than compression stockings alone for the prevention of venous thromboembolism after elective neurosurgery and does not cause excessive bleeding. (N Engl J Med 1998; 339:80-5.)

Impact of Thrombophilia on Risk of Arterial Ischemic Stroke or Cerebral Sinovenous Thrombosis in Neonates and Children A Systematic Review and Meta-Analysis of Observational Studies

Background— The aim of this study was to estimate the impact of thrombophilia on risk of first childhood stroke through a meta-analysis of published observational studies. Methods and Results— A systematic search of electronic databases (Medline via PubMed, EMBASE, OVID, Web of Science, The Cochrane Library) for studies published from 1970 to 2009 was conducted. Data on year of publication, study design, country of origin, number of patients/control subjects, ethnicity, stroke type (arterial ischemic stroke [AIS], cerebral venous sinus thrombosis [CSVT]) were abstracted. Publication bias indicator and heterogeneity across studies were evaluated, and summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with fixed-effects or random-effects models. Twenty-two of 185 references met inclusion criteria. Thus, 1764 patients (arterial ischemic stroke [AIS], 1526; cerebral sinus venous thrombosis [CSVT], 238) and 2799 control subjects (neonate to 18 years of age) were enrolled. No significant heterogeneity was discerned across studies, and no publication bias was detected. A statistically significant association with first stroke was demonstrated for each thrombophilia trait evaluated, with no difference found between AIS and CSVT. Summary ORs (fixed-effects model) were as follows: antithrombin deficiency, 7.06 (95% CI, 2.44 to 22.42); protein C deficiency, 8.76 (95% CI, 4.53 to 16.96); protein S deficiency, 3.20 (95% CI, 1.22 to 8.40), factor V G1691A, 3.26 (95% CI, 2.59 to 4.10); factor II G20210A, 2.43 (95% CI, 1.67 to 3.51); MTHFR C677T (AIS), 1.58 (95% CI, 1.20 to 2.08); antiphospholipid antibodies (AIS), 6.95 (95% CI, 3.67 to 13.14); elevated lipoprotein(a), 6.27 (95% CI, 4.52 to 8.69), and combined thrombophilias, 11.86 (95% CI, 5.93 to 23.73). In the 6 exclusively perinatal AIS studies, summary ORs were as follows: factor V, 3.56 (95% CI, 2.29 to 5.53); and factor II, 2.02 (95% CI, 1.02 to 3.99). Conclusions— The present meta-analysis indicates that thrombophilias serve as risk factors for incident stroke. However, the impact of thrombophilias on outcome and recurrence risk needs to be further investigated.

Aryl hydrocarbon receptor control of a disease tolerance defence pathway

Disease tolerance is the ability of the host to reduce the effect of infection on host fitness. Analysis of disease tolerance pathways could provide new approaches for treating infections and other inflammatory diseases. Typically, an initial exposure to bacterial lipopolysaccharide (LPS) induces a state of refractoriness to further LPS challenge (endotoxin tolerance). We found that a first exposure of mice to LPS activated the ligand-operated transcription factor aryl hydrocarbon receptor (AhR) and the hepatic enzyme tryptophan 2,3-dioxygenase, which provided an activating ligand to the former, to downregulate early inflammatory gene expression. However, on LPS rechallenge, AhR engaged in long-term regulation of systemic inflammation only in the presence of indoleamine 2,3-dioxygenase 1 (IDO1). AhR-complex-associated Src kinase activity promoted IDO1 phosphorylation and signalling ability. The resulting endotoxin-tolerant state was found to protect mice against immunopathology in Gram-negative and Gram-positive infections, pointing to a role for AhR in contributing to host fitness.

Predicting disease recurrence in patients with previous unprovoked venous thromboembolism: a proposed prediction score (DASH).

Summary.  Background:  In patients with unprovoked venous thromboembolism (VTE), the optimal duration of anticoagulation is anchored on estimating the risk of disease recurrence.

Rate of inhibitor development in previously untreated hemophilia A patients treated with plasma-derived or recombinant factor VIII concentrates: a systematic review

Summary.  Background: Different rates of inhibitor development after either plasma‐derived (pdFVIII) or recombinant (rFVIII) FVIII have been suggested. However, conflicting results are reported in the literature. Objectives: To systematically review the incidence rates of inhibitor development in previously untreated patients (PUPs) with hemophilia A treated with either pdFVIII or rFVIII and to explore the influence of both study and patient characteristics. Methods: Summary incidence rates (95% confidence interval) from all included studies for both pdFVIII and rFVIII results were recalculated and pooled. Sensitivity analysis was used to investigate the effect of study design, severity of disease and inhibitor characteristics. Meta‐regression and analysis‐of‐variance were used to investigate the effect of covariates (testing frequency, follow‐up duration and intensity of treatment). Results: Two thousand and ninety‐four patients (1167 treated with pdFVIII, 927 with rFVIII; median age, 9.6 months) from 24 studies were investigated and 420 patients were observed to develop inhibitors. Pooled incidence rate was 14.3% (10.4–19.4) for pdFVIII and 27.4% (23.6–31.5) for rFVIII; high responding inhibitor incidence rate was 9.3% (6.2–13.7) for pdFVIII and 17.4% (14.2–21.2) for rFVIII. In the multi‐way anova study design, study period, testing frequency and median follow‐up explained most of the variability, while the source of concentrate lost statistical significance. It was not possible to analyse the effect of intensity of treatment or trigger events such as surgery, and to completely exclude multiple reports of the same patient or changes of concentrate. Conclusions: These findings underscore the need for randomized controlled trials to address whether or not the risk of inhibitor in PUPs with hemophilia A differs between rFVIII and pdFVIII.

Risk of Recurrence After a First Episode of Symptomatic Venous Thromboembolism Provoked by a Transient Risk Factor: A Systematic Review

BACKGROUND We aimed to determine the risk of recurrence for symptomatic venous thromboembolism (VTE) provoked by different transient risk factors. DATA SOURCES MEDLINE, EMBASE, and Cochrane Collaboration Registry of Randomized Trials databases were searched. STUDY SELECTION Prospective cohort studies and randomized trials of patients with a first episode of symptomatic VTE provoked by a transient risk factor and treated for at least 3 months were identified. DATA EXTRACTION Number of patients and recurrent VTE during the 0- to 12-month and 0- to 24-month intervals after stopping therapy, study design, and provoking risk factor characteristics were extracted. DATA SYNTHESIS Annualized recurrence rates were calculated and pooled across studies. At 24 months, the rate of recurrence was 3.3% per patient-year (11 studies, 2268 patients) for all patients with a transient risk factor, 0.7% per patient-year (3 studies, 248 patients) in the subgroup with a surgical factor, and 4.2% per patient-year (3 studies, 509 patients) in the subgroup with a nonsurgical factor. In the same studies, the rate of recurrence after unprovoked VTE was 7.4% per patient-year. The rate ratio for a nonsurgical compared with a surgical factor was 3.0 and for unprovoked thrombosis compared with a nonsurgical factor was 1.8 at 24 months. CONCLUSIONS The risk of recurrence is low if VTE is provoked by surgery, intermediate if provoked by a nonsurgical risk factor, and high if unprovoked. These risks affect whether patients with VTE should undergo short-term vs indefinite treatment.

Risk of recurrence after venous thromboembolism in men and women: patient level meta-analysis

Objective To determine the effect of sex on the risk of recurrent venous thromboembolism in all patients and in patients with venous thromboembolism that was unprovoked or provoked (by non-hormonal factors). Data source Comprehensive search of electronic databases (Medline, Embase, CINAHL, Cochrane Central Register of Controlled Trials) until July 2010, supplemented by review of conference abstracts and contact with content experts. Study selection Seven prospective studies investigating an association between D-dimer, measured after anticoagulation was stopped, and disease recurrence in patients with venous thromboembolism. Data extraction Patient level databases were obtained, transferred to a central database, checked, and completed with further information provided by authors. Data synthesis 2554 patients with a first venous thromboembolism had follow-up for a mean of 27.1 (SD 19.6) months. The one year incidence of recurrent venous thromboembolism was 5.3% (95% confidence interval 4.1% to 6.7%) in women and 9.5% (7.9% to 11.4%) in men, and the three year incidence of recurrence was 9.1% (7.3% to 11.3%) in women and 19.7% (16.5% to 23.4%) in men. Among patients with unprovoked venous thromboembolism, men had a higher risk of recurrence than did women (hazard ratio 2.2, 95% confidence interval 1.7 to 2.8). After adjustment for women with hormone associated initial venous thromboembolism, the risk of recurrence remained higher in men (hazard ratio 1.8, 1.4 to 2.5). In patients with provoked venous thromboembolism, occurring after exposure to a major risk factor, recurrence of disease did not differ between men and women (hazard ratio 1.2, 0.6 to 2.4). In women with hormone associated venous thromboembolism and no other risk factors, recurrence was lower than that in women with unprovoked venous thromboembolism and no previous hormone use (hazard ratio 0.5, 0.3 to 0.8). Conclusion In patients with a first unprovoked venous thromboembolism, men have a 2.2-fold higher risk of recurrent venous thromboembolism than do women, which remained 1.8-fold higher in men after adjustment for previous hormone associated venous thromboembolism in women. In patients with a first provoked venous thromboembolism, risk of recurrence does not differ between men and women with or without hormone associated venous thromboembolism. Indefinite anticoagulation may be given greater consideration in men than in women after a first venous thromboembolism.

Low-molecular-weight heparin for the long-term treatment of symptomatic venous thromboembolism: meta-analysis of the randomized comparisons with oral anticoagulants

Summary.  Background: The management of venous thromboembolism (VTE) requires an initial treatment with unfractionated heparin (UFH) or low‐molecular‐weight heparin (LMWH), followed by oral anticoagulants (OA) for at least 3 months. OA treatment however, requires laboratory monitoring of anticoagulation, carries a definite risk of bleeding, and may be contraindicated in some patients. As an alternative to vitamin K antagonists, subcutaneous LMWH has been proposed and evaluated in randomized clinical trials, but they are all small studies that lack the power to establish if these two treatment modalities are equivalent in efficacy or safety. Objectives: The objective of this review was to evaluate the efficacy (VTE recurrence) and safety (bleeds and deaths) of long‐term treatment of VTE with LMWH compared with OA. A secondary endpoint was to evaluate the effect of LMWH on cancer mortality. Methods: Computerized searches of MedLine and EmBase were performed. In addition, randomized clinical trials were located through personal communication with colleagues, and through the manual scanning of meeting proceedings and reference lists of relevant studies. When necessary, the authors of the selected papers were called to obtain additional information. Two reviewers (AI and FG) reviewed and extracted data independently using a standard form. The primary analysis was performed for efficacy and safety endpoints on an intention‐to‐treat basis for the study period of randomized treatment. A meta‐regression analysis was used to investigate the relationship between daily dose and clinical outcome. Results: Seven studies that fulfillled our predefined criteria were identified, for a total of 1379 patients. When all studies were combined, a statistically non‐significant reduction in the risk of VTE (OR 0.66; 95% confidence interval [CI] 0.41, 1.07) and in the risk of major bleeding (OR 0.45; 95% CI 0.18, 1.11) in favor of LMWH treatment was found. No difference in total mortality (OR 1.19; 95% CI 0.78, 1.83) or in cancer‐related mortality was observed between the LMWH and the OA treatment. Conclusions: The results of this meta‐analysis indicate that a 3‐month course of LMWH is as effective and safe as a corresponding period of OA treatment, and may thus be considered as a valuable alternative option for patients in whom OA treatment appears contraindicated or problematic.

Does the clinical presentation and extent of venous thrombosis predict likelihood and type of recurrence? A patient-level meta-analysis

Summary.  Aim: To determine if the mode of presentation of venous thromboembolism (VTE), as deep vein thrombosis (DVT) or pulmonary embolism (PE), predicts the likelihood and type of recurrence. Methods: We carried out a patient‐level meta‐analysis of seven prospective studies in patients with a first VTE who were followed after anticoagulation was stopped. We used Kaplan‐Meier analysis to determine the cumulative incidence of recurrent VTE according to mode of presentation, and multivariable Cox regression to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for mode of and extent of DVT as potential risk factors for recurrence. Results: The 5‐year cumulative rate of recurrent VTE in 2554 patients was 22.6%. In 869 (36.1%) patients with PE, the 5‐year rate of any recurrence (DVT or PE) was 22.0%, and recurrence as PE was 10.6%. In 1365 patients with proximal DVT, the 5‐year recurrence rate was 26.4%, and recurrence with PE was 3.6%. The risk of recurrence as PE was 3.1‐fold greater in patients presenting with symptomatic PE than in patients with proximal DVT (HR, 3.1; 95% CI, 1.9–5.1). Patients with proximal DVT had a 4.8‐fold higher cumulative recurrence rate than those with distal DVT (HR, 4.8; 95% CI, 2.1–11.0). Conclusion: Whilst DVT and PE are manifestations of the same disease, the phenotypic expression is predetermined. Patients presenting with PE are three times more likely to suffer recurrence as PE than patients presenting with DVT. Patients presenting with calf DVT are at low risk of recurrence and at low risk of recurrence as PE.

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

BACKGROUND In patients with a first unprovoked venous thromboembolism (VTE), an elevated d-dimer level after anticoagulation is stopped is a risk factor for recurrent VTE. However, questions remain about the utility of measuring d-dimer in clinical practice. PURPOSE To determine whether the timing of testing, patient age, and the cut point used to define a positive or negative result affect the ability of d-dimer testing to distinguish risk for recurrent disease. DATA SOURCES Comprehensive search of electronic databases (MEDLINE, EMBASE, CINAHL, and the Cochrane Central Register of Controlled Trials) until July 2010, supplemented by reviewing conference abstracts and contacting content experts. STUDY SELECTION 7 prospective studies that investigated an association between d-dimer, measured after stopping anticoagulation, and disease recurrence in patients with a first unprovoked VTE (proximal deep venous thrombosis, pulmonary embolism, or both). DATA EXTRACTION Patient-level databases were obtained, transferred to a central database, checked, completed with further information provided by study investigators, and pooled into a single database. DATA SYNTHESIS 1818 patients with a first unprovoked VTE were followed for a mean of 26.9 months (SD, 19.1). A study-stratified multivariate Cox regression model, which included patient age, sex, hormone therapy use at the time of the index event, body mass index, timing of postanticoagulation d-dimer testing, and inherited thrombophilia as possible confounders, indicated that the hazard ratio for d-dimer status (positive vs. negative) was 2.59 (95% CI, 1.90 to 3.52). Only male sex had a significant effect on risk for recurrent VTE independent of d-dimer status. The Cox regression model and the log-rank test confirmed that the risk for recurrent VTE was higher in patients with a positive d-dimer result than in those with a negative result, regardless of the timing of postanticoagulation d-dimer testing or patient age. No study- or assay-specific d-dimer effect was found, and reassessing the analysis after recoding data according to specific quantitative d-dimer cut points (500 µg/L and 250 µg/L) did not change the results. LIMITATIONS Unmeasured variables could have affected the risk for recurrent VTE. The study population was predominantly white. CONCLUSION In patients with a first unprovoked VTE who have their d-dimer level measured after stopping anticoagulation, the timing of d-dimer testing, patient age, and the assay cut point used do not affect the ability of d-dimer to distinguish patients with a higher or lower risk for recurrent VTE.