Oral surgery in patients on oral anticoagulant therapy: a randomized comparison of different INR targets.
Explore the source record for details and available documents.
Administration, Oral↗
Biomedical subjects
M Moia
Publications and source records attributed to M Moia.
The first ambulatory screening on thromboembolism: a multicentre, cross-sectional, observational study on risk factors for venous thromboembolism.
OBJECTIVES: To assess the prevalence of risk factors for venous thromboembolism (VTE) and the prevalence of recent (<1 year) VTE [including superficial vein thrombosis (SVT), deep vein thrombosis (DVT) and pulmonary embolism (PE)] amongst patients attending general practitioner (GP) surgeries. DESIGN: Multicentre, cross-sectional, observational study. SETTING: A total of 1536 GP surgeries. PARTICIPANTS: A total of 15 180 adult, co-operative subjects, who had consulted their GP for a health disorder and signed the informed consent form. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Prevalence of known VTE risk factors graded according to importance and prevalence of recent (<1 year) VTE events (including SVT), based on interviews. RESULTS: About 1:5 patients had at least one strong risk factor and about 1:20 had at least two risk factors, with no difference between sexes. The prevalence of strong risk factors increased with age. Most were related to medical conditions: history of SVT and/or DVT/PE, heart failure and malignancy. About 3:4 women and 2:3 men had at least one moderate to weak risk factor; nearly 1:2 women and 1:3 men had at least two moderate to weak risk factors. The most common were: history of VTE, smoking, history of miscarriage, estrogen therapy, obesity, and varicose veins. Overall, 80% women and 67% men had at least one risk factor, and 50% women and 35% men had at least two risk factors. The prevalence of recent (<1 year) VTE was 3.4% in women and 2.4% in men, and increased with age. The majority of cases were SVT in both sexes (2.5% in women and 1.5% in men). CONCLUSIONS: The prevalence of risk factors for VTE amongst patients attending GP surgeries is high. GPs should bear this in mind during their daily practice.
Adolescent↗
Heparin-induced thrombocytopenia and warfarin-induced skin necrosis in a child with severe protein C deficiency: successful treatment with dermatan sulfate and protein C concentrate.
Explore the source record for details and available documents.
Anticoagulants↗
Incidence of cancer after a first episode of idiopathic venous thromboembolism treated with 3 months or 1 year of oral anticoagulation.
BACKGROUND: A prolonged treatment with oral anticoagulants has been claimed to reduce the incidence of newly diagnosed cancer in the long-term follow-up of patients with venous thromboembolism. OBJECTIVES: In a multicenter prospective study we assessed the incidence of newly diagnosed clinically overt cancer in patients with a first episode of idiopathic venous thromboembolism (VTE) treated with oral anticoagulants for 3 months or 1 year. PATIENTS AND METHODS: Consecutive patients with an idiopathic venous thromboembolism who had completed 3 months of oral anticoagulant therapy without having a recurrence, bleeding or newly diagnosed cancer were randomized to discontinue oral anticoagulant therapy or to continue it for nine additional months. Idiopathic venous thromboembolism was defined as thrombosis occurring in the absence of known cancer, known thrombophilia, or temporary risk factors for venous thromboembolism. All patients were followed up for at least 1 year after randomization. RESULTS: A total of 429 patients, 265 patients with DVT and 164 with PE, were followed up for an average of 43.7 months after randomization. A newly diagnosed cancer occurred in 32 patients (7.5%), 13 (6.2%) of the 210 patients treated for 3 months and 19 (8.7%) of the 219 patients treated for 1 year (RR = 0.71, 95% confidence interval 0.36-1.41). CONCLUSIONS: The incidence of newly diagnosed clinically overt cancer is not reduced in patients with idiopathic venous thromboembolism treated with 1-year anticoagulant treatment compared with patients treated for 3 months.
Administration, Oral↗
Warfarin and acenocoumarol dose requirements according to CYP2C9 genotyping in North-Italian patients.
Explore the source record for details and available documents.
Acenocoumarol↗
Prevention of venous thrombosis with elastic stockings during long-haul flights: the LONFLIT 5 JAP study.
The aim of this study was to evaluate deep venous thrombosis (DVT) prophylaxis with specific elastic stockings in long-haul flights (11-13 hours), in high-risk subjects. A group of 300 subjects was included; 76 were excluded for several problems including concomitant treatments; 224 were randomized into two groups (stockings vs. controls) to evaluate prophylaxis with below-knee stockings. An exercise program was used in both groups. Scholl (UK) Flight Socks (14-17 mmHg of pressure at the ankle) were used. DVT was diagnosed with ultrasound scanning. The femoral, popliteal, and tibia] veins were scanned before and within 90 minutes after the flights. Of the 205 included subjects, 102 controls and 103 treated subjects completed the study. Drop-outs were due to flight connection problems. Age, gender, and risk distributions were comparable in the two groups. In the treatment group (103 subjects; mean age, 42; SD 9; M:F, 55:48), one limited, distal DVT was observed (0.97%). In the control group (102 subjects; mean age, 42.1; SD 10.3; M:F, 56:46), six subjects (5.8%) had a DVT. There were no superficial thromboses. The difference in DVT incidence is significant (p<0.0025; six times greater in the control group). Intention-to-treat analysis counts 18 failures in the control group (12 lost to follow-up + six thromboses) of 112 subjects (15.8%) versus eight failures (7.3%) in the treatment group (p<0.05). The tolerability of the stockings was very good and there were no complaints or side effects. All events were asymptomatic. Considering these observations, Scholl Flight Socks are effective in reducing the incidence of DVT in high-risk subjects.
Adult↗
Venous thromboembolism in the antiphospholipid syndrome: management guidelines for secondary prophylaxis.
Venous thromboembolism (VTE) in patients suffering from the antiphospholipid syndrome (APS) has been reported in almost any location of the vessel tree and the risk of recurrences has been found in several studies to be more closely associated with the presence of lupus anticoagulant than with the positivity for anti-cardiolipin antibodies. The thrombophilic state of APS raises the problem of the secondary prophylaxis to avoid VTE recurrences. For APS patients with VTE, published data appear to support a longer warfarin treatment if compared with the standard management of antiphospholipid (aPL)-negative patients with VTE. The question of how long oral anticoagulant treatment should be continued for APS patients, however, remains unanswered. Concerning the intensity of anticoagulation, several authors recommend a target international normalized ratio (INR) between 3.0 and 4.0 to efficiently protect from VTE recurrences. A recent decision analysis study does support such a suggestion. On the contrary, in a few prospective studies regimens with lower target INRs appear to be effective, and some authors therefore recommend a target INR of between 2.0 and 3.0. Specific large and prospective trials are needed to address this question. Until such information becomes available, individualized treatment according to the patient's individual risk factors for both bleeding and thrombosis is the general practice.
Administration, Oral↗
Central venous catheter-related complications in patients with hematological malignancies: a retrospective analysis of risk factors and prophylactic measures.
UNLABELLED: We retrospectively analyzed the incidence of thrombotic and infectious complications in relation with the use of central venous catheters (CVCs), in a series of patients with hematological malignancies and low platelet and leucocyte counts. PATIENTS AND METHODS: 126 patients with hematological malignancies were analyzed. A total of 207 CVCs were implanted: 137 centrally (CICCs) and 70 peripherally (PICCs). The median duration of the CVCs was 19 days for a total of 4051 catheter-days. Antithrombotic prophylaxis was unfractionated heparin (UFH), 2,500 IU daily by 24 h continuous infusion in 169 CVCs, low molecular weight heparin (LMWH), 3,800 IU daily by single bolus intravenous injection (i.v.) in 21 and warfarin in one. No prophylaxis was given in 16 CVCs. Thrombotic complications developed in 15.5% of the CVCs (7.9 events/1000 catheter days), and the frequency of infectious complications was 10.6% (5.2 events/1000 catheter days). On multivariate analysis thromboses were more frequent and earlier with PICCs than CICCs (p = 0.0001), and in patients on UFH (16.6%) than in LMWH prophylaxis (4.7%), but the last difference was not statistically significant. In conclusions the incidence of thrombotic complications in our series was comparable to that observed in non-thrombocytopenic patients and was significantly higher in those carrying PICC than CICC (p = 0.0001). There were fewer thrombotic events in the patients receiving i.v. LMWH prophylaxis than in those receiving i.v. UFH. The use of anticoagulants was safe and not associated with hemorrhages.
Adolescent↗
p-Methylthioamphetamine and 1-(m-chlorophenyl)piperazine, two non-neurotoxic 5-HT releasers in vivo, differ from neurotoxic amphetamine derivatives in their mode of action at 5-HT nerve endings in vitro.
The mechanism underlying the serotoninergic neurotoxicity of some amphetamine derivatives, such as p-chloroamphetamine (pCA) and 3,4-methylenedioxymethamphetamine (MDMA), is still debated. Their main acute effect, serotonin (5-HT) release from nerve endings, involves their interaction with 5-HT transporters (SERTs), as substrates. Although this interaction is required for the neurotoxic effects, 5-HT release alone may not be sufficient to induce long-term 5-HT deficits. Some non-neurotoxic compounds, including p-methylthioamphetamine (MTA) and 1-(m-chlorophenyl)piperazine (mCPP), have 5-HT releasing properties in vivo and in brain slices comparable to that of neurotoxic amphetamine derivatives. We measured 5-HT release in superfused rat brain synaptosomes preloaded with [3H]5-HT, a model that distinguishes a releasing effect from reuptake inhibition. MTA and mCPP induced much lower release than pCA and MDMA. The striking difference between our findings in synaptosomes and those obtained in vivo or in brain slices is probably related to a different compartmentalisation of 5-HT in the different experimental models. Studies in synaptosomes, where the vesicular storage of 5-HT is predominant, could therefore bring to light differences between neurotoxic and non-neurotoxic 5-HT releasing agents which cannot be appreciated in other experimental models and might be useful to identify the mechanisms responsible for the neurotoxicity induced by amphetamine derivatives.
Amphetamines↗
Three months versus one year of oral anticoagulant therapy for idiopathic deep venous thrombosis. Warfarin Optimal Duration Italian Trial Investigators.
BACKGROUND: In patients with idiopathic deep venous thrombosis, continuing anticoagulant therapy beyond three months is associated with a reduced incidence of recurrent thrombosis during the period of therapy. Whether this benefit persists after anticoagulant therapy is discontinued is controversial. METHODS: Patients with a first episode of idiopathic proximal deep venous thrombosis who had completed three months of oral anticoagulant therapy (with warfarin, in 97 percent of the cases and acenocoumarol in 3 percent) were randomly assigned to the discontinuation of oral anticoagulants or to their continuation for nine additional months. The primary study outcome was recurrence of symptomatic, objectively confirmed venous thromboembolism during at least two years of follow-up. RESULTS: The primary intention-to-treat analysis showed that of 134 patients assigned to continued oral anticoagulant therapy, 21 had a recurrence of venous thromboembolism (15.7 percent; average follow-up, 37.8 months), as compared with 21 of 133 patients assigned to the discontinuation of oral anticoagulant therapy (15.8 percent; average follow-up, 37.2 months), resulting in a relative risk of 0.99 (95 percent confidence interval, 0.57 to 1.73). During the initial nine months after randomization (after all patients received three months of therapy), 1 patient had a recurrence while receiving oral anticoagulant therapy (0.7 percent), as compared with 11 of the patients assigned to the discontinuation of oral anticoagulant therapy (8.3 percent; P=0.003). The incidence of recurrence after the discontinuation of treatment was 5.1 percent per patient-year in patients in whom oral anticoagulant therapy was discontinued after 3 months (95 percent confidence interval, 3.2 to 7.5 percent; average interval since discontinuation, 37.2 months) and 5.0 percent per patient-year in patients who received an additional 9 months of oral anticoagulant therapy (95 percent confidence interval, 3.1 to 7.8 percent; average interval since discontinuation, 29.4 months). None of the recurrences were fatal. Four patients had non-fatal major bleeding during the extended period of anticoagulant therapy (3.0 percent). CONCLUSIONS: In patients with idiopathic deep venous thrombosis, the clinical benefit associated with extending the duration of anticoagulant therapy to one year is not maintained after the therapy is discontinued.
Acenocoumarol↗
Analysis of the tissue factor pathway inhibitor gene and antigen levels in relation to venous thrombosis.
Tissue factor pathway inhibitor (TFPI) inhibits tissue factor-induced coagulation. The major part of TFPI is releasable by heparin. We recently found eight patients with thrombosis and low levels of heparin-releasable TFPI in whom we investigated the TFPI gene for mutations. A transition of G to A coding for Valine264Methionine in the heparin-binding domain was found. The Val264Met polymorphism had an allele frequency of 3% in 96 healthy individuals. A silent polymorphism was identified in TFPI exon IV (T-->C), which does not alter Tyrosine 56. Apart from Val264Met, which was detected in one out of the eight patients, no other mutations in the TFPI gene were found in patients with low heparin-releasable TFPI. Analysis of Val264Met in 317 patients with deep vein thrombosis (DVT) and 292 controls showed no association between Val264Met and DVT. However, a study of total TFPI antigen levels in 122 DVT patients and 126 controls demonstrated an association between TFPI levels and venous thrombosis (P = 0.0001). These results provide evidence for a relationship between venous thrombosis and total TFPI level as a possible risk factor, whereas they do not support a link between DVT and mutations in the nine exons of the TFPI gene.
Analysis of Variance↗
In vitro binding studies with two hypericum perforatum extracts--hyperforin, hypericin and biapigenin--on 5-HT6, 5-HT7, GABA(A)/benzodiazepine, sigma, NPY-Y1/Y2 receptors and dopamine transporters.
Interactions between neurotransmitter receptors involved in the pathophysiology of depression, anxiety and ethanol consumption and two extracts (hydromethanolic and lipophilic extracts obtained with hypercritical CO2) from Hypericum Perforatum L or St. John's wort (SJW) and three constituents (hyperforin, hypericin and biapigenin) were evaluated by in vitro binding assays. The two extracts, tested at 10 microg/ml, did not inhibit ligand binding at the following receptors: serotonin 5-HT6 and 5-HT7, benzodiazepine, sigma and neuropeptide Y (NPY) Y1 and Y2 receptors. The hydromethanolic extract, but not the lipophilic extract, interacted with GABA(A) receptors (IC50 5.5 microg/ml), while both interacted with the dopamine (DA) transporters, albeit with high IC50 values (24.5 and 12.9 microg/ml, respectively). Biapigenin (1 microg/ml, 2 microM) inhibited ligand binding at benzodiazepine receptors only (IC50: 2 microM). Hyperforin (1 microg/ml, 2 microM) only inhibited [3H]WIN-35,428 binding to DA transporters, although the IC50 (5 microM) was higher than the IC50 found for inhibition of the synaptosomal DA reuptake (0.8 microM). This finding extended the same observation previously described for the 5-HTergic system to the DAergic system, confirming that the inhibition of monoamine reuptake is due to a different mechanism than that of synthetic antidepressants. Hypericin showed micromolar affinities for both NPY-Y1 and Y2 receptors and for sigma receptors (IC50 3-4 microM). These hypericin activities might be of interest because NPY and sigma receptors have been associated with anxiety disorders, depressive illnesses and ethanol consumption. However, they were present at relatively high hypericin concentrations, and were also light-dependent (i.e. the IC50 values increased when binding assays were carried out in the dark). Thus, our in vitro binding results may suggest that either the pharmacological effects of SJW are due to other molecules than hypericin or hyperforin (other constituents or active metabolites), or that the mechanism of action is different from those that have been considered up to now.
Animals↗
Effect of computer-aided management on the quality of treatment in anticoagulated patients: a prospective, randomized, multicenter trial of APROAT (Automated PRogram for Oral Anticoagulant Treatment).
BACKGROUND AND OBJECTIVES: We carried out a prospective, randomized trial to test whether a computer-based decision support system to initiate and maintain oral anticoagulant (OA) treatment can improve the laboratory quality of therapy. DESIGN AND METHODS: Two separate sets of patients on oral anticoagulants, in five Italian anticoagulant clinics, were studied: 335 patients in the first three months of treatment (stabilization phase), 916 patients (775 patient-years) beyond the third month of treatment (maintenance phase). Patients were randomized to a computerized system, which included algorithms able to suggest OA dosing and to schedule appointments (computer-aided dosing) or to an arm in which OA were prescribed by the same teams of expert physicians without such algorithms (control group). Primary outcomes were: A) the percentage of patients reaching a stable state of anticoagulation during each of the first three months of treatment; B) the percentage of time individuals spent within the aimed therapeutic range (maintenance phase). RESULTS: Patients in the computer-aided dosing group achieved a stable state significantly faster (p<0.01) and they spent more time within the therapeutic range during maintenance (p<0.001) than controls. The favorable effect of computer-aided dosing was mainly due to a reduction of the time spent below the therapeutic range and was associated with an increase of mean INR value, of anticoagulant drug dosage, and with a reduction of the number of appointments per patient (all changes significant: p<0.001). INTERPRETATION AND CONCLUSIONS: The computer decision-aided support improves the laboratory quality of anticoagulant treatment, both during long-term maintenance and in the early, highly unstable phase of treatment, and it also significantly reduces the number of scheduled laboratory controls.
Algorithms↗
Accuracy of a portable prothrombin time monitor (Coagucheck) in patients on chronic oral anticoagulant therapy: a prospective multicenter study.
A portable prothrombin time (PT) monitor allows patients on oral anticoagulant therapy (OAT) to measure their PT at home. The purpose of the study was to evaluate the accuracy and precision of a portable PT monitor (Coagucheck, Roche Diagnostics, Mannheim, Germany) as compared with laboratory methods. The prospective study was conducted in four centers of the Italian Federation of Anticoagulation Clinics. A one-month instruction phase was followed by a six-month surveillance phase. Seventy-eight subjects on stable OAT (48 men, 30 women, age range: 18-75) were selected on a volunteer basis. Dual measurements of INR values were performed in each subject both from finger capillary blood by the monitor and from venous blood by the Anticoagulation Clinic laboratory in three instruction sessions. The mean difference (bias) of the monitor INR results when compared with the average of laboratory INR and monitor INR results was -0.025 (limits of agreement-LA: -0.84/+0.81 INR units). The mean bias was -0.0675 (LA: -0.37/+0.23), +0.018 (LA: -0.39/+0.35), and +0.039 (LA: -0.49/+0.55), respectively, for INR values lower than 2.0, between 2.0 and 3.0, and greater than 3.0. The overall precision coefficient of monitor INR was 0.370, while it was 0.23, 0.46, 0.29, and 0.21, respectively, in Centers 1, 2, 3, and 4. The overall variation coefficient was 6.5% while it was 3.7%, 8.5%, 4.7%, and 4.9%, respectively, in Centers 1, 2, 3, and 4. Coagucheck has an acceptable level of accuracy for INR values in the range between 2.0 and 3.0. A wide variation in monitor performance was found among centers.
Administration, Oral↗
Oral anticoagulation treatment in the elderly: a nested, prospective, case-control study.
BACKGROUND: Whether elderly patients are at increased risk of complications during oral anticoagulant treatment (OAT) is still a matter of debate. METHOD: Bleeding and thrombotic events occurring during OAT in 461 patients, aged 75 years or older when they started OAT, and in 461 patients younger than 70 years, matched for sex, OAT indication, and treating center, were examined in a prospective, multicenter, inception-cohort study. RESULTS: Bleeding rate was 9.9% and 6.6% patient-years in elderly and young patients, respectively (P = .07), and 2.1% and 1.1% for major bleeding (P = .19); 6 and 1 events, respectively, were fatal (all intracranial, relative risk, 6.4; P = .05). In the elderly, bleeding rate was lower (4.5%) for international normalized ratios (INRs) between 2.0 and 2.9; it was higher during the first 90 treatment days (P = .05) and when arterial vascular disease was the indication for OAT (P = .03). Thrombosis rate was 4.2% and 2.5% patient-years in elderly and young patients, respectively (P = .10); however, 13 and 5 events were fatal (relative risk, 2.8; P = .04). Thrombosis rate was lower (1.5%) for INRs between 2.0 and 2.9; it was higher during the first 90 treatment days (P<.001) and 6 of 7 venous events occurred at lower than 2.0 INRs. CONCLUSIONS: A nonsignificant trend was noted toward a higher rate of both bleeding and thrombotic complications in elderly vs matched younger patients. Intracranial bleeding and fatal thrombotic events were significantly more frequent in the elderly. Our results also indicate that lower than 2.0 INRs do not preclude bleeding in the elderly nor offer adequate protection from thrombotic events. Moderate anticoagulation (2.0-3.0 INRs) in elderly patients seems the safest and most effective.
Administration, Oral↗
The G1691 --> A mutation of factor V, but not the G20210 --> A mutation of factor II or the C677 --> T mutation of methylenetetrahydrofolate reductase genes, is associated with venous thrombosis in patients with lupus anticoagulants.
Arterial and venous thrombosis are the most common manifestations of antiphospholipid syndrome. To investigate whether genetic determinants contribute to their thrombotic risk, we studied the prevalence of the G1691 --> A mutation in the gene coding for factor V, the G20210 --> A mutation in the prothrombin gene and the C677 --> T mutation in the methylenetetrahydrofolate reductase gene in 152 patients with lupus anticoagulants. One hundred and twenty-eight cases (84%) also had increased titres of anticardiolipin antibodies. History of thrombosis was present in 96 patients (63%); 67 suffered from venous thrombosis only, 23 cases had arterial thrombosis only, six patients had both venous and arterial thrombosis. Five patients were heterozygous for the G1691 --> A mutation in the factor V gene (3%). All of them (100%) suffered from venous thrombosis compared with 68 out of the 147 cases without the mutation (46%) (P = 0.0474). The prevalence of the G20210 --> A mutation in the prothrombin gene was evaluated in 145 patients; eight of these patients were heterozygous (5%). Four of these patients (50%) experienced venous thrombosis compared with 65 out of the 137 patients without the mutation (47%) (P = ns). Neither mutation was associated with arterial thrombotic events. No patient carried both mutations. The C677 --> T mutation in the methylenetetrahydrofolate reductase gene was assessed in 83 patients; 15 of them (18%) were homozygous and 37 (44%) were heterozygous. There was no significant association between the status of the mutation and history of venous and arterial thrombosis. No significant correlation was found among the three groups. In conclusion, only the G1691 --> A mutation in the factor V gene was associated with the thrombotic risk of patients with lupus anticoagulants.
Antibodies, Anticardiolipin↗
A comparison of the safety and efficacy of oral anticoagulation for the treatment of venous thromboembolic disease in patients with or without malignancy.
The optimal long-term treatment of acute venous thromboembolism (VTE) in patients with malignancy remains undefined. In particular, based on current evidence, it is uncertain whether secondary prophylaxis using standard intensity oral anticoagulant therapy is associated with higher risks of bleeding and recurrent thrombosis in patients with cancer than in those without cancer. This study compared the outcome of anticoagulation courses in 95 patients with malignancy with those of 733 patients without malignancy. All patients were participants in a large, nation-wide population study and were prospectively followed from the initiation of their oral anticoagulant therapy. Based on 744 patient-years of treatment and follow-up, the rates of major (5.4% vs 0.9%), minor (16.2% vs 3.6%) and total (21.6% vs 4.5%) bleeding were statistically significantly higher in cancer patients compared with patients without cancer. Bleeding was also a more frequent cause of early anticoagulation withdrawal in patients with malignancy (4.2% vs. 0.7%; p <0.01; RR 6.2 (95% CI 1.95-19.4). There was a trend towards a higher rate of thrombotic complications in cancer patients (6.8% vs. 2.5%; p = 0.058; RR 2.5 [CI 0.96-6.5]) but this did not achieve statistical significance. In the group of patients with cancer, the bleeding rate was high across the different INR categories and was independent of the temporally associated International Normalized Ratio (INR). In contrast, the bleeding rate was increased only with INR values greater than 4.5 in the group of patients without cancer. The rate of thrombotic events was significantly higher in both cohorts when the INR was less than 2.0. In conclusion, patients with malignancy treated with oral anticoagulants have a higher rate of bleeding and possibly an increased risk of recurrent thrombosis compared with patients without malignancy. Safer and more effective anticoagulant therapy is needed for this challenging group of patients.
Administration, Oral↗
The incidence of venous thromboembolism in asymptomatic carriers of a deficiency of antithrombin, protein C, or protein S: a prospective cohort study.
Deficiencies of antithrombin, protein C, and protein S are associated with an increased risk of venous thromboembolism. The objective of this study was to prospectively assess the incidence of venous thromboembolism in nontreated asymptomatic subjects with such a deficiency. We conducted a prospective cohort study in asymptomatic family members of unselected patients who presented with a venous thromboembolic event and who were found to have a deficiency of antithrombin, protein C, or protein S. No anticoagulant prophylaxis was given to the study participants, except during risk periods for venous thromboembolism. All venous thromboembolic events were diagnosed by objective diagnostic tests. A total of 208 individuals with a mean age of 37 years (range, 15 to 79) were included in the study. A total of 611 patient observation years was obtained. Nine venous thromboembolic events occurred, resulting in an annual incidence of 1.5% (95% confidence interval [CI], 0.7 to 2.8) for the 3 deficiencies combined. Five of these events occurred spontaneously, resulting in an annual incidence of spontaneous venous thromboembolism of 0.8% (95% CI, 0.3 to 1.9). For antithrombin, protein C, and protein S deficiencies separately, this figure was 1.6%, 1.0%, and 0.4%, respectively. Thirty-four subjects experienced a total of 40 risk periods during which 4 venous thromboembolic events occurred (10% per risk period). We conclude that the use of continuous anticoagulant prophylaxis seems not warranted in asymptomatic individuals with a deficiency of antithrombin, protein C, or protein S. During risk periods for venous thromboembolism, adequate anticoagulant prophylaxis is necessary.
Adult↗