Revised classification criteria for antiphospholipid syndrome and the thrombotic risk in patients with autoimmune diseases

BACKGROUND: The classification criteria for antiphospholipid syndrome (APS) were updated in 2006. Objective: The aim of the study was to analyze associations between clinical complications and laboratory test abnormalities typical for APS in a group of patients with autoimmune diseases, based on the recently updated criteria. PATIENTS/METHODS: Three hundred and thirty-six patients were enrolled into the study, with the majority (n = 235) suffering from systemic lupus erythematosus. Laboratory determinations included: lupus anticoagulant (LA), anticardiolipin (aCL) and anti-beta(2)-glycoprotein I (anti-beta(2)GPI) antibodies (ABs) [of both immunoglobulin G (IgG) and IgM class]. RESULTS: A significant association was found between laboratory and clinical features of APS; odds ratios (ORs) for thrombosis associated with the presence of LA, aCL, and anti-beta(2)GPI Abs were 4.04 [95% CI: 2.44-6.68], 3.71 (95% CI 2.32-5.92) and 2.57 (95% CI 1.60-4.1), respectively. Detailed analysis showed marked differences between the risk of clinical complications associated with the presence of an antibody in the IgG class (OR 4.15, 95% CI 2.42-7.12, and OR 4.77, 95% CI 2.37-9.61 for aCL and anti-beta(2)GPI, respectively) and in the IgM class (OR 2.2, 95% CI 1.31-3.70, and OR 1.9, 95% CI 1.15-3.14 for aCL and anti-beta(2)GPI, respectively). The postulated inclusion of anti-beta(2)GPI antibody positivity into the previous laboratory criteria changed only slightly the number of patients diagnosed with APS (from 112 to 117). CONCLUSIONS: The updated APS classification criteria clearly represent a step forward. However, our results argue against the use of overall positivity for aCL or anti-beta(2)GPI, and favor a clear distinction between the IgG and IgM classes of antiphospholipid ABs. Patients with both LA and anti-beta(2)GPI IgG or LA and aCL IgG positivity may represent the subgroups at the highest risk of thrombotic complications.     

Development of a calibrated automated thrombography based thrombin generation test in mouse plasma

BACKGROUND: Mouse models have become increasingly important in thrombosis research. However, only a limited number of assays are available for assessment of the coagulation system in mouse plasma. OBJECTIVES: To quantify tissue factor-initiated thrombin generation in murine platelet-rich and platelet-free plasma and to develop a test for measurement of resistance to activated protein C (APC) in mouse plasma. METHODS: Thrombin generation was monitored with calibrated automated thrombography (CAT) using a low-affinity fluorogenic substrate for thrombin. RESULTS: To overcome the higher activity of coagulation inhibitors in mouse plasma as compared with human plasma, the reaction temperature was lowered to 33 degrees C and the assay was carried out at a 2-fold higher final plasma dilution (1:3) than commonly used for CAT in human plasma. This increased the endogenous thrombin potential (ETP) 4- to 5-fold and enabled reliable measurement of thrombin generation in both platelet-free and platelet-rich mouse plasma. For the APC resistance measurement, the reaction conditions were further optimized with respect to tissue factor, phospholipid, APC and CaCl(2) concentrations. The test was validated using plasma of mice with different genetic background with respect to the factor V Leiden mutation (FV Leiden). Mice homozygous for FV Leiden had higher APC sensitivity ratios (mean 5.46; 95% CI 4.88-6.03) than heterozygous FV Leiden mice (mean 4.21; 95% CI 3.53-4.89) and than wild-type mice (mean 2.71; 95%CI 2.15-3.27). CONCLUSIONS: We have established reaction conditions for measurement of thrombin generation and APC resistance in mouse plasma. This assay enables evaluation of the coagulation system and the function of the protein C system in mouse models.     

High rate of unprovoked recurrent venous thrombosis is associated with high thrombin‐generating potential in a prospective cohort study

Summary. Objective: To determine the predictive value of measurement of parameters of thrombin generation for unprovoked recurrent venous thrombosis. Methods: Measurements were made of thrombin generation in a prospective cohort study of 188 patients with a first episode of venous thrombosis that was unprovoked, or provoked by a non‐surgical trigger. Results: The endogenous thrombin potential (ETP) was the only parameter associated with unprovoked recurrent thrombosis in a multivariate model [hazard ratio (HR) 1.3 per 100 nmol L min^?1 increase, 95% confidence interval (CI) 1.0–1.6]. Patients with a high ETP had a significantly higher rate of unprovoked recurrence than those with a low ETP (HR 2.9, 95% CI  1.3–6.6, cumulative recurrence at 4 years 27% vs. 11%). Patients with an unprovoked first event had a significantly higher rate of unprovoked recurrence than those with a provoking factor (HR 2.7, 95% CI  1.2–6.1), and in these patients there was a significantly higher rate of unprovoked recurrence in association with a high ETP (HR 4.0, 95% CI  1.3–11.8). After adjustment for D‐dimer, thrombophilia, sex, and whether or not the first event was unprovoked, a high ETP remained a significant predictor of recurrence (HR 2.6, 95% CI  1.2–6.0). Conclusions: This study demonstrates a high rate of unprovoked recurrent venous thrombosis in patients presenting with a first episode of venous thrombosis and a high ETP.     

Antiphospholipid, anti-beta 2-glycoprotein-I and anti-oxidized-low-density-lipoprotein antibodies in antiphospholipid syndrome

Antiphospholipid antibodies (aPL), anti-beta 2-glycoprotein I (anti-beta 2-GPI) and anti-oxidized-low-density lipoprotein (LDL) antibodies are all implicated in the pathogenesis of antiphospholipid syndrome. To investigate whether different autoantibodies or combinations thereof produced distinct effects related to their antigenic specificities, we examined the frequencies of antiphospholipid syndrome (APS)-related features in the presence of different antibodies [aPL, beta 2-GPI, anti-oxidized low density lipoprotein (LDL)] in 125 patients with APS. Median follow-up was 72 months: 58 patients were diagnosed as primary APS and 67 as APS plus systemic lupus erythematosus (SLE). Anticardiolipin antibodies (aCL), anti-beta 2-GPI and anti-oxidized LDL antibodies were determined by ELISA; lupus anticoagulant (LA) by standard coagulometric methods. Univariate analysis showed that patients positive for anti-beta 2-GPI had a higher risk of recurrent thrombotic events (OR = 3.64, 95% CI, p = 0.01) and pregnancy loss (OR = 2.99, 95% CI, p = 0.004). Patients positive for anti-oxidized LDL antibodies had a 2.24-fold increase in the risk of arterial thrombosis (2.24, 95% CI, p = 0.03) and lower risk of thrombocytopenia (OR = 0.41 95% CI, p = 0.04). Patients positive for aCL antibodies had a higher risk of pregnancy loss (OR = 4.62 95% CI, p = 0.001). When these data were tested by multivariate logistic regression, the association between anti-beta 2-GPI and pregnancy loss and the negative association between anti-oxidized LDL antibodies and thrombocytopenia disappeared.     

Use of a new silica clotting time for diagnosing lupus anticoagulant in patients who meet the clinical criteria for antiphospholipid syndrome

The silica clotting time (SCT) is a phospholipid-dependent coagulation assay used for the laboratory diagnosis of lupus anticoagulant (LA) antibodies. The sensitivity and specificity of a new commercial SCT for identifying LA in patients who meet the clinical criteria for antiphospholipid syndrome (APS), and its association with thrombotic events were evaluated here. Forty-five patients who met the clinical criteria for APS according to the Sapporo International Consensus Statement were examined. Sixty-nine patients who did not meet the clinical criteria for APS, and 20 blood donors were used as controls. Plasma samples from the patients and controls were tested for LA using a new commercial SCT with low and high synthetic phospholipid concentrations. The results were compared with those obtained by diluted Russell's viper venom time (dRVVT) and activated partial thromboplastin time (APTT). SCT's sensitivity for identifying LA in patients who met the clinical criteria of APS was higher compared to APTT and dRVVT (53.3% vs. 31.1% and 31.1%), and the specificities of these assays were 96.6%, 100%, and 98.9%, respectively. When dRVVT was combined with SCT, and dRVVT was combined with APTT their sensitivities were 57.7% and 48.8%, and their specificities were 96.6% and 98.9%, respectively. A stepwise logistic regression analysis indicated that the combination of dRVVT with SCT was associated with total thrombotic events (odds ratio (OR)=11.5, 95% confidence interval (CI)=1.25-106.3, P=0.031) as well as with venous thrombosis (OR=4.09, 95% CI=1.16-14.43, P=0.028). According to our results, SCT is the most sensitive assay for identifying LA in patients who meet the clinical criteria for APS. Moreover, the highest sensitivity was reached with a combination of SCT and dRVVT. The method's association with total thrombotic events and venous thrombosis was in fact significant.     

Clinical accuracy for diagnosis of antiphospholipid syndrome in systemic lupus erythematosus: evaluation of 23 possible combinations of antiphospholipid antibody specificities

Summary. Objectives: To evaluate the clinical accuracy of antiphospholipid antibody (aPL) specificities both individually and/or in combination, in a wide cohort of systemic lupus erythematosus (SLE) patients in an attempt to identify a panel of tests that may provide the best accuracy for diagnosing antiphospholipid syndrome (APS). Patients and Methods: This study included 230 patients (218 women, mean age 42.7 ± 11.9 years, mean disease duration 12.2 ± 8.7 years), all fulfilling the 1982 criteria for SLE. All patients were tested for lupus anticoagulant (LA), anti‐cardiolipin (aCL), anti‐β₂glycoprotein I (anti‐β2GPI), solid phase anti‐prothrombin (aPT), anti‐phosphatidylserine/prothrombin (aPS/PT), and anti‐phosphatidylethanolamine (aPE) antibodies. Sensitivity, specificity and predictive values were calculated. The diagnostic accuracy for each combination of tests was assessed by ROC and their area under the curve analysis as well as by the Youden’s index (YI). Results: Testing for six aPL derived 23 possible combinations of results. Among them, LA + anti‐β₂GPI + aPS/PT had the best diagnostic accuracy for APS as a whole and individually for both thrombosis and pregnancy loss (AUC 0.712, OR 3.73 [95% CI 1.82–5.38], P = 0.0001, YI = 0.32 and AUC 0.709, OR 3.75 [95% CI 2.13–6.62], P = 0.0001, YI = 0.37 and AUC 0.677, OR 4.82 [95% CI 2.17–10.72], P = 0.0007, YI = 0.38, respectively) and the best specificity when compared with all the other obtainable combination of tests. Triple positivity for LA + anti‐β₂GPI + aPS/PT was more strongly associated with clinical events (thrombosis and/or PL) when compared with double or single positivity (OR 23.2 [95% CI 2.57–46.2] vs. OR 7.3 [95% CI 2.21–25.97], OR 5.7 [95% CI 2.12–17.01] or OR 3.11 [95% CI 1.56–7.8] for single positivity for LA, aPS/PT and anti‐β₂GPI, respectively). Conclusions: Combining LA, anti‐β₂GPI and aPS/PT improves the diagnostic power and helps in stratifying the risk for each patient, according to their aPL profile.     

Increased acquired activated protein C resistance in unselected patients with hematological malignancies

Summary.  Background: We have previously found that activation of coagulation in patients with various hematological malignancies was apparently not initiated by tissue factor (TF). Acquired activated protein C (APC) resistance may be another mechanism responsible for such hypercoagulation, and has been demonstrated in patients with solid tumors, but not in patients with hematological malignancy. Objective: To investigate acquired APC resistance in a hypercoagulable cohort of patients with hematological malignancies. Patients/methods: Blood samples from 93 patients with acute myeloid leukemia (AML), chronic lymphatic leukemia, multiple myeloma, or non-Hodgkin's lymphoma, were analyzed before start and after completion of cancer therapy. APC resistance was measured using calibrated automated thrombography. The APC sensitivity ratio (APC-SR) was calculated as the ratio of the endogenous thrombin potential (ETP) determined in plasma probed with either APC or buffer. Results: Untreated patients were found to have higher APC-SR than healthy controls, and patients with AML had higher APC-SR as compared to the other diagnoses, both findings being consistent with acquired APC resistance. The acquired APC resistance was partly ameliorated with cancer treatment. Decreased levels of protein S and TF pathway inhibitor were inversely correlated to APC resistance. Conclusions: APC resistance may contribute to the hypercoagulable state in hematological malignancies.     

Clinical course of high‐risk patients diagnosed with antiphospholipid syndrome

See also Galli M. The antiphospholipid triangle. This issue, pp 234–6. Summary. Background: The characteristics and the clinical course of antiphospholipid syndrome (APS) in high‐risk patients that are positive for all three recommended tests that detect the presence of antiphospholipid (aPL) antibodies have not been described. Methods: This retrospective analysis of prospectively collected data examined patients referred to Italian Thrombosis Centers that were diagnosed with definite APS and tested positive for aPL [lupus anticoagulant (LA), anti‐cardiolipin (aCL), and anti‐β2‐glycoprotein I (β2GPI) antibodies]. Laboratory data were confirmed in a central reference laboratory. Results: One hundred and sixty patients were enrolled in this cohort study. The qualifying events at diagnosis were venous thromboembolism (76 cases; 47.5%), arterial thromboembolism (69 cases; 43.1%) and pregnancy morbidity (11 cases; 9.7%). The remaining four patients (2.5%) suffered from catastrophic APS. The cumulative incidence of thromboembolic events in the follow‐up period was 12.2% (95%CI, 9.6–14.8) after 1 year, 26.1% (95%CI, 22.3–29.9) after 5 years and 44.2% (95%CI, 38.6–49.8) after 10 years. This was significantly higher in those patients not taking oral anticoagulants as compared with those on treatment (HR=2.4 95%CI 1.3–4.1; P < 0.003). Major bleeding associated with oral anticoagulant therapy was low (0.8% patient/years). Ten patients died (seven were cardiovascular deaths). Conclusions: Patients with APS and triple positivity for aPL are at high risk of developing future thromboembolic events. Recurrence remains frequent despite the use of oral anticoagulants, which significantly reduces the risk of thromboembolism.     

Markers of cardiovascular risk in patients with antiphospholipid syndrome: A meta-analysis of literature studies

Abstract

Several studies reported on the association between antiphospholipid syndrome (APS) and venous thrombosis. In contrast, little is known about cardiovascular (CV) risk in APS. We performed a meta-analysis on the impact of APS on major markers of CV risk.

Studies on the relationship between APS and common carotid artery intima-media thickness (CCA-IMT), internal carotid artery IMT (ICA-IMT), carotid bifurcation IMT (BIF-IMT), prevalence of carotid plaques, flow-mediated dilation (FMD), nitrate-mediated dilation (NMD), and ankle-brachial index (ABI) were systematically searched in PubMed, Web of Science, Scopus, and EMBASE databases. Twenty case-control studies (668 cases, 678 controls) were included. Compared to controls, APS patients showed a higher CCA-IMT (mean difference [MD] 0.11 mm; 95% CI 0.07, 0.14), ICA-IMT (MD 0.08 mm; 95% CI 0.05, 0.11), BIF-IMT (MD 0.09 mm; 95% CI 0.06, 0.12) and a higher frequency of carotid plaques (OR 3.87; 95% CI 1.61, 9.31). Moreover, a lower FMD was found in APS subjects than in controls (MD –4.49%; 95% CI –6.20, –2.78), with no differences in NMD (MD –1.80%; 95% CI –4.01, 0.42). Finally, an increased prevalence of pathological ABI was found in APS patients compared to controls (OR 7.26; 95% CI 1.77, 29.71).

Despite heterogeneity among studies, APS appears significantly associated with markers of subclinical atherosclerosis and CV risk. These findings can be useful to plan adequate prevention strategies and therapeutic approaches.     

Acquired activated protein C resistance associated with IgG antibodies against beta2-glycoprotein I and prothrombin as a strong risk factor for venous thromboembolism

BACKGROUND: Venous thromboembolic events such as deep vein thrombosis and pulmonary embolism are common manifestations of antiphospholipid syndrome. Our aim was to clarify the roles of anti-phospholipid (aPL) antibodies in the pathogenesis of venous thromboembolism (VTE) in patients with systemic lupus erythematosus (SLE). METHODS AND RESULTS: We examined anti-cardiolipin/beta2-glycoprotein I (anti-CL/beta2-GPI) antibody concentrations, anti-phosphatidylserine/prothrombin (anti-PS/PT) antibody concentrations, and lupus anticoagulant (LA) activity in 87 patients with SLE (21 with VTE and 66 without thrombosis). Both anti-CL/beta2-GPI and anti-PS/PT antibodies strongly correlated with LA activity. Multivariate logistic analysis confirmed that both anti-CL/beta2-GPI and anti-PS/PT antibodies were significant independent risk factors for VTE (odds ratios = 4.98 and 7.54, respectively; 95% confidence intervals, 1.51-16.4 and 2.30-24.7, respectively). We therefore studied the in vitro effects of IgG fractions containing anti-CL/beta2-GPI or anti-PS/PT antibodies on the anticoagulant activity of activated protein C (APC) and found that purified IgG containing anti-CL/beta2-GPI or anti-PS/PT antibodies significantly hampered the anticoagulant activity of APC. We also studied the ability of IgG fractions to impede the anticoagulant activity of APC before and after complete removal of anti-CL/beta2-GPI or anti-PS/PT antibodies by adsorption. Removal of anti-CL/beta2-GPI or anti-PS/PT antibodies from all positive IgG samples clearly decreased the inhibitory effect of those samples on APC anticoagulant activity. CONCLUSIONS: Anti-CL/beta2-GPI and anti-PS/PT antibodies independently cause APC resistance, which may contribute to risk of VTE in patients with SLE.     

Coagulation factors and the protein C system as determinants of thrombin generation in a normal population.

BACKGROUND: Thrombin generation is a powerful tool to probe overall plasma coagulability. OBJECTIVE: To determine which plasma factors influence the various parameters of the thrombin generation curve, for example lag time, peak height and endogenous thrombin potential (ETP), under different experimental conditions. PATIENTS AND METHODS: Plasma levels of coagulation factors and inhibitors, as well as thrombin generation at 1 pm tissue factor (TF) +/- thrombomodulin (TM) and at 13.6 pm TF +/- activated protein C (APC), were determined in plasma from 140 healthy individuals. Data were analysed by multiple regression models. RESULTS: Thrombin generation increased with age and was higher in females than in males. Under all conditions, the lag time was mainly dependent on the levels of free tissue factor pathway inhibitor (TFPI), free protein S (PS), factor VII (FVII), FIX and fibrinogen. The major determinants of thrombin generation (ETP and peak height) at 1 pm TF were fibrinogen, FXII (despite inhibition of contact activation), free TFPI and antithrombin (AT), both in the absence and in the presence of TM. Thrombin generation in the presence of TM was also dependent on protein C levels. At 13.6 pm TF, thrombin generation was determined by prothrombin, AT, fibrinogen, free TFPI and FV levels in the absence of APC, and by free TFPI, free PS and FX levels in the presence of APC. CONCLUSIONS: The lag time, ETP and peak height of thrombin generation depend on the levels of multiple coagulation factors and inhibitors. The specific assay determinants vary with the experimental conditions.     

The anticardiolipin assay is required for sensitive screening for antiphospholipid antibodies.

The importance of testing for anticardiolipin antibodies (aCL) in the diagnosis of antiphospholipid syndrome (APS) in patients with thrombosis has recently been challenged (ISTH SSC meeting, Boston 2002). We have analyzed the antiphospholipid serology of 123 patients with persistent antiphospholipid antibodies (aPL) attending our hematology department. The cohort was tested for anti-beta(2)-glycoprotein I (beta(2)-GPI) antibodies and aCL of IgG and IgM class and for lupus anticoagulant (LA). Ninety-six of these patients fulfilled Sapporo clinical criteria for APS and 70 of these patients had venous and/or arterial thrombosis. Patients with LA plus anti-beta(2)-GPI antibodies had significantly higher levels of IgG aCL and anti-beta(2)-GPI antibodies than those exhibiting positivity for only LA or anti-beta(2)-GPI antibodies (P < 0.05). Patients with aCL IgG levels over 60 GPLU were found in all cases to be positive for LA and anti-beta(2)-GPI antibodies; 25.2% (31/123) of all patients and 26.04% (25/96) of patients fulfilling Sapporo clinical criteria for APS were positive for aCL only. The mean IgG aCL level in the Sapporo clinical criteria positive patients who had aCL only was 11.5 GPLU (normal < 5 GPLU). These data indicate that omission of aCL testing from the clinical investigation of APS could lead to a failure to diagnose the syndrome in a proportion of patients.     

Argatroban dosing of patients with heparin-induced thrombocytopenia and an elevated aPTT due to antiphospholipid antibody syndrome

OBJECTIVE: To describe the clinical characteristics, management, and outcomes of patients with heparin-induced thrombocytopenia with thrombosis (HITTS) or without thrombosis (HIT) who also had an elevated baseline activated partial thromboplastin time (aPTT) due to antiphospholipid antibody syndrome (APS). CASE SUMMARY: Four patients with HIT/HITTS and an elevated baseline aPTT due to APS were identified. Two patients had venous thrombosis, 1 had limb ischemia, and 1 had isolated HIT. All 4 were managed with a weight-based fixed dose of argatroban without laboratory monitoring. None of the patients had thrombotic or bleeding complications once therapy was initiated. DISCUSSION: Management of patients with HIT/HITTS and an abnormal baseline aPTT due to APS is problematic. We review alternative management strategies, such as monitoring direct thrombin inhibitors with the ecarin clotting time or thrombin inhibition time or using an alternative anticoagulant, such as fondaparinux. As of March 13, 2006, none of these management strategies has been evaluated in a clinical trial for this patient population. We report the successful use of weight-based, fixed-dose argatroban without laboratory monitoring in patients with APS. CONCLUSIONS: Use of a fixed-dose argatroban regimen without laboratory monitoring is a potential management strategy for patients with HIT/HITTS and an elevated baseline aPTT due to APS.     

Antibodies against phospholipids and beta 2-glycoprotein I increase the risk of recurrent venous thromboembolism in patients without systemic lupus erythematosus

We studied the prognostic significance of antiphospholipid antibodies for recurrence of venous thromboembolism (VTE), in 71 patients admitted for acute VTE (deep-vein thrombosis or pulmonary embolism) in a single internal medicine unit. Lupus anticoagulant (LA), antibodies directed against beta 2-glycoprotein I (beta 2GPI) and antibodies against both beta 2GPI and a mixture of phospholipids (cardiolipin, phosphatidylserine and phosphatidic acid) (APAs) were measured. The patients were followed-up (mean 4.9 years) to determine the time to the next VTE. We found LA in nine patients, anti-beta 2GPI antibodies in seven patients and APAs in six patients. The cumulative risk of recurring VTE was higher in patients with beta 2GPI-binding antibodies (hazard ratio 12.6, 95% CI 1.5-104.9; p = 0.0029). The risk associated with APAs was 11.5 (95% CI 1.3-98.9; p = 0.0049) and that for LA was 3.7 (95% CI 0.9-15.6; p = 0.055). The risk of VTE recurring was higher both in patients with antibodies directed against beta 2GPI, and in patients with antibodies directed against beta 2GPI and a mixture of phospholipids, than in patients without these antibodies.      

A randomized clinical trial of high-intensity warfarin vs. conventional antithrombotic therapy for the prevention of recurrent thrombosis in patients with the antiphospholipid syndrome (WAPS).

BACKGROUND: The optimal intensity of oral anticoagulation for the prevention of recurrent thrombosis in patients with antiphospholipid antibody syndrome is uncertain. Retrospective studies show that only high-intensity oral anticoagulation [target international normalized ratio (INR) >3.0] is effective but a recent randomized clinical trial comparing high (INR range 3.0-4.0) vs. moderate (INR 2.0-3.0) intensities of anticoagulation failed to confirm this assumption. METHODS: We conducted a randomized trial in which 109 patients with antiphospholipid syndrome (APS) and previous thrombosis were given either high-intensity warfarin (INR range 3.0-4.5, 54 patients) or standard antithrombotic therapy (warfarin, INR range 2.0-3.0 in 52 patients or aspirin alone, 100 mg day(-1) in three patients) to determine whether intensive anticoagulation is superior to standard treatment in preventing symptomatic thromboembolism without increasing the bleeding risk. RESULTS: The 109 patients enrolled in the trial were followed up for a median time of 3.6 years. Mean INR during follow-up was 3.2 (SD 0.6) in the high-intensity warfarin group and 2.5 (SD 0.3) (P < 0.0001) in the conventional treatment patients given warfarin. Recurrent thrombosis was observed in six of 54 patients (11.1%) assigned to receive high-intensity warfarin and in three of 55 patients (5.5%) assigned to receive conventional treatment [hazard ratio for the high intensity group, 1.97; 95% confidence interval (CI) 0.49-7.89]. Major and minor bleeding occurred in 15 patients (two major) (27.8%) assigned to receive high-intensity warfarin and eight (three major) (14.6%) assigned to receive conventional treatment (hazard ratio 2.18; 95% CI 0.92-5.15). CONCLUSIONS: High-intensity warfarin was not superior to standard treatment in preventing recurrent thrombosis in patients with APS and was associated with an increased rate of minor hemorrhagic complications.     

Survival and prognostic factors of death risk in antiphospholipid syndrome: results of 8-year follow-up

AIM: To evaluate survival and mortality in antiphospholipid syndrome (APS) as well as prognostic factors of APS deterioration. MATERIAL AND METHODS: We retrospectively studied 248 case histories of patients admitted to the Institute of Rheumatology for 8 years. Primary APS was diagnosed in 35 patients, SLE + APS (according to criteria of ACR, 1982)--in 122 patients and SLE without APS--in 91 patients. Mean age was 31.2 +/- 15.0 years (range from 14 to 63), median length of follow-up from the time of diagnosis was 11.9 +/- 5.4 years. During 8 year period all the patients annually and the latest 5 years at least twice a year were examined for the presence of IgG and IgM-anticardiolipin antibodies (aCL) and lupus anticoagulant (LA). Thrombotic events were verified with special techniques. RESULTS: Thirty-eight patients (15%) died during the follow-up period. Mean age of the decreased was 35.4 +/- 12.2 years (range 21-52 years) and the disease duration 8.6 +/- 8.2 years (range 0.6-20), the median length of the survival from the time of the diagnosis was 6.2 +/- 4.3 years. The 8-year survival for SLE patients without APS was 98%, for those with SLE + APS-75% and for patients with primary APS-83%. The presence of APS in SLE patients was significantly associated with high mortality (chi 2 = 12.3, freedom = 4, p = 0.006). Cox regression analysis revealed that the activity of the disease at onset, arterial thrombosis, especially recurrent, thrombocytopenia, valvular disease of the heart, capillaritis, digital necrosis and nephritis were independent risk factors for mortality (p < 0.05). CONCLUSION: Thus, long-term follow-up is necessary for patients with antiphospholipid antibodies especially with APS which lowers survival of SLE patients. Such patients need early corrective therapy to prevent thrombotic events.     

Association of increased fibrinogen concentration with impaired activation of anticoagulant protein C

BACKGROUND: Low levels of activated protein C (APC) are a risk factor for venous thrombosis. The mechanisms leading to interindividual differences in APC are not totally elucidated. Protein C is activated by the thrombin-thrombomodulin complex. As thrombin binds to fibrinogen and thrombomodulin through a common region, it is conceivable that fibrinogen influences the activation of protein C. This would help to explain the association between high levels of fibrinogen and an increased thrombotic risk. METHODS: We analyzed the association between circulating APC levels and fibrinogen concentration in 382 healthy subjects. Subsequently, we studied the effect of increasing fibrinogen concentrations on the APC generation on cultured endothelial cells. RESULTS: An independent inverse association between circulating APC levels and fibrinogen was found [betacoefficient, -0.16; 95% confidence interval (95% CI) -0.26, -0.06; P = 0.001]. For each 100 mg dL(-1) increase in fibrinogen, the independent risk of having low APC levels (<0.7 ng mL(-1)) was almost three times higher (OR 2.8; 95% CI 1.1, 7.2; P = 0.04). Accordingly, a notable association between increasing fibrinogen concentrations and the reduction in the thrombin-thrombomodulin dependent activation of protein C on endothelial cells was found (r = -0.57; P = 0.002). CONCLUSIONS: We present evidence of an inverse association between circulating APC and fibrinogen levels. According to this finding together with the results of our in vitro experiments, we propose that the impairment in the generation of APC on endothelial cells constitutes a new prothrombotic mechanism of fibrinogen.     

High thrombin generation measured in the presence of thrombomodulin is associated with an increased risk of recurrent venous thromboembolism

Summary.  Background:  The assessment of the risk of recurrent venous thromboembolism (VTE) is important to determine the optimal duration of secondary prophylaxis. The risk can be estimated by measuring individual parameters reflecting hypercoagulability. Because of the large numbers of such putative parameters, the assessment in individual patients is complex. Application of global assays reflecting the pro-/anti-coagulant balance in vivo would be desirable. Objectives:  To investigate the relationship between recurrent VTE and thrombin generation (TG). Patients-methods:  Two hundred and fifty-four patients were followed-up after a first episode of unprovoked, objectively documented VTE for a period of 2.7 years after discontinuation of treatment with vitamin K antagonists. TG was measured 1 month after discontinuation of treatment as endogenous thrombin potential (ETP), peak thrombin and lag-time in the presence or absence of thrombomodulin. The study outcome was objectively documented symptomatic recurrent VTE. Results:  Patients with ETP or peak (measured in the presence of thrombomodulin) of >960 n m _*min or >193 n m had hazard ratios (HR) (95% CI) for recurrent VTE of 3.41 (1.34–8.68) or 4.57 (1.70–12.2) as compared with those with an ETP <563 n m _*min or peak <115 n m . Patients with lag-time <14.5 min had HR of 3.19 (1.29–7.89) as compared with those with lag-time >20.8 min. HR for ETP, peak or lag-time measured in the absence of thrombomodulin were smaller than those measured in the presence of thrombomodulin. Conclusions:  The measurement of TG helps to identify patients at higher risk of VTE recurrence. The increased risk may be better appreciated if the test is performed in the presence of thrombomodulin.     

狼疮抗凝物伴凝血因子Ⅷ、Ⅸ和Ⅺ缺乏的检验诊断:附13例报告

目的 探讨狼疮抗凝物伴凝血因子(Ⅷ、Ⅸ和Ⅺ)缺乏的检验诊断方法.方法 检测13例狼疮抗凝物伴凝血因子(Ⅷ、、Ⅸ和Ⅺ)缺乏患者(包括长期服用氯丙嗪的精神分裂症5例、抗磷脂综合征2例、天疱疹1例、原因未明5例)、1O例血友病A患者和48名健康志愿者的凝血因子活性、凝血因子抗体、抗心磷脂抗体(ACA)、狼疮抗凝物(LA)以及凝血酶的生成.结果 13例狼疮抗凝物伴凝血因子(Ⅷ、Ⅸ和Ⅺ)缺乏患者的活化部分凝血活酶时间(APTT)延长,凝血因子Ⅷ、Ⅸ、Ⅺ活性(FⅧ∶C、FⅨ∶C、FⅪ∶C)降低,针对这些凝血因子的抗体及LA均为阳性,6例ACA为阳性.其中LA阳性、伴凝血因子(Ⅷ、Ⅸ和Ⅺ)缺乏组中,11例无出血患者的凝血酶生成试验(TGT)的延迟时间值为(5.60±1.18)min,高于正常对照组的(1.88±0.25)min,差异具有统计学意义(t=10.05,P＜0.01);达峰时间值为(8.11±1.91)min,高于正常对照组的(4.10±0.36)min,差异具有统计学意义(t=8.83,P＜0.01);凝血酶生成潜力(ETP)值为(1640.87±279.80)nmol·L-1·min-1,高于遗传性血友病A组的(734.59±118.30)nmol·L-1·min-1,差异具有统计学意义(t=9.77,P＜0.01);ETP比值为(86.00±14.66)%,高于遗传性血友病A组的(38.50±6.20)%,差异具有统计学意义(t=9.77,P＜0.01).遗传性血友病A组的达峰时问值为(8.01±1.81)min,高于正常对照组的(4.10±0.36)min,差异具有统计学意义(t=8.20,P＜0.01);而延迟时间值为(2.01±0.84)min,与正常对照组的(1.88±0.25)min比较,差异无统计学意义(t=1.26,P＞0.05).结论 狼疮抗凝物伴凝血因子(Ⅷ、Ⅸ和Ⅺ)缺乏和遗传性血友病是以APTT、PT、PLT和APTT纠正试验作为筛选试验;以LA、FⅧ∶C、FⅨ∶C、FⅪ∶C和它们的抗体检测作为确诊试验;检测LA和ACA可为寻找病因提供依据;ETP值和ETP比值是判断LA阳性伴凝血因子(Ⅷ、Ⅸ和Ⅺ)缺乏患者临床是否出血的较敏感指标.