Suzanne C. Cannegieter

Optimal oral anticoagulant therapy in patients with mechanical heart valves

BACKGROUND The optimal intensity of oral anticoagulant therapy for patients with mechanical heart valves (i.e., the level at which thromboembolic complications are effectively prevented without excessive bleeding) is not known. We attempted to determine the optimal intensity by calculating the incidence of both complications at different levels of anticoagulation. METHODS Data were collected on all patients with mechanical heart valves who have been seen at four regional Dutch anticoagulation clinics since 1985. The primary outcome events were episodes of thromboembolism or major bleeding. The intensity-specific incidence of each type of event was calculated as the number of events that occurred at a certain intensity of anticoagulation (expressed in terms of the international normalized ratio [INR]) divided by the number of patient-years during which the INR was at this level in the total patient population. RESULTS A total of 1608 patients were followed during 6475 patient-years. Cerebral embolism occurred in 43 patients (0.68 per 100 patient-years) and peripheral embolism in 2 (0.03 per 100 patient-years). Intracranial and spinal bleeding occurred in 36 patients (0.57 per 100 patient-years) and major extracranial bleeding in 128 (2.1 per 100 patient-years). The optimal intensity of anticoagulation, at which the incidence of both complications was lowest, was achieved when the INR was between 2.5 and 4.9. CONCLUSIONS The intensity of anticoagulant therapy for patients with prosthetic heart valves is optimal when the INR is between 2.5 and 4.9. To achieve this level of anticoagulation, a target INR of 3.0 to 4.0 is recommended.

Thromboembolic and bleeding complications in patients with mechanical heart valve prostheses.

BackgroundPatients with mechanical heart valve prostheses may experience valve thrombosis and subsequent systemic embolism for which they are treated with oral anticoagulant therapy. It is essential to know reliable estimates of the risks and benefits of this therapy in order to answer a number of clinical questions rationally. We sought to obtain more precise estimates of the risks and benefits by combining the data from individual studies by using meta-analysis. Methods and ResultsWe searched for studies in which the incidences were reported of embolic or bleeding complications in patients with mechanical heart valve prostheses. They were collected from the Medline and Current Contents database and by cross-references between 1970 and 1992. Since most studies vary greatly in many respects, we used a number of inclusion criteria, thus selecting comparable studies of acceptable quality only. The influence of antithrombotic therapy, valve position, and valve type was analyzed by univariate and by multivariate analysis with Poisson regression techniques. Forty-six studies were found, including 13 088 patients studied for 53 647 patient-years. We found an incidence of major embolism in the absence of antithrombotic therapy of 4 per 100 patient-years. With antiplatelet therapy this risk was 2.2 per 100 patient-years, and with cumarin therapy it was reduced to 1 per 100 patient-years. This risk varied with the type and the site of the prosthesis. A prosthesis in mitral position increased the risk almost twice as compared with the aortic position. Tilting disc valves and bileaflet valves showed a lower incidence of major embolism than caged ball valves. An incidence of major bleeding was found in patients treated with cumarin derivatives of 1.4 per 100 patient-years. The incidence of bleeding became significantly higher with the addition of antiplatelet therapy, although this did not decrease the risk of thromboembolism any further. ConclusionsThese data provide a reference for future studies and give adequate risk estimates for clinical decision making.

Incidence and mortality of venous thrombosis: a population-based study

Background:  Estimates of the incidence of venous thrombosis (VT) vary, and data on mortality are limited.

Epidemiology of cancer-associated venous thrombosis

Cancer-associated venous thrombosis is a common condition, although the reported incidence varies widely between studies depending on patient population, start and duration of follow-up, and the method of detecting and reporting thrombotic events. Furthermore, as cancer is a heterogeneous disease, the risk of venous thrombosis depends on cancer types and stages, treatment measures, and patient-related factors. In general, cancer patients with venous thrombosis do not fare well and have an increased mortality compared with cancer patients without. This may be explained by the more aggressive type of malignancies associated with this condition. It is hypothesized that thromboprophylaxis in cancer patients might improve prognosis and quality of life by preventing thrombotic events. However, anticoagulant treatment leads to increased bleeding, particularly in this patient group, so in case of proven benefit of thromboprophylaxis, only patients with a high risk of venous thrombosis should be considered. This review describes the literature on incidence of and risk factors for cancer-associated venous thrombosis, with the aim to provide a basis for identification of high-risk patients and for further development and refinement of prediction models. Furthermore, knowledge on risk factors for cancer-related venous thrombosis may enhance the understanding of the pathophysiology of thrombosis in these patients.

Activation of coagulation system during air travel: a crossover study

BACKGROUND There is an increased risk of venous thrombosis after air travel, but the underlying mechanism is unclear. Our aim was to ascertain whether flying leads to a hypercoagulable state. METHODS We did a crossover study in 71 healthy volunteers (15 men, 56 women), in whom we measured markers of activation of coagulation and fibrinolysis before, during, and after an 8-h flight. The same individuals participated in two control exposure situations (8-h movie marathon and daily life) to separate the effect of air travel on the coagulation system from those of immobilisation and circadian rhythm. To study the effect of risk factors for thrombosis, we included participants with the factor V Leiden mutation (n=11), those who took oral contraceptives (n=15), or both (n=15), as well as 30 individuals with no specific risk factors. FINDINGS After the flight, median concentrations of thrombin-antithrombin (TAT) complex increased by 30.1% (95% CI 11.2-63.2), but decreased by 2.1% (-11.2 to 14) after the cinema and by 7.9% (-16.2 to -1.2) after the daily life situation. We recorded a high response in TAT levels in 17% (11 of 66) of individuals after air travel (3% [2 of 68] for movie marathon; 1% [1 of 70] in daily life). These findings were most evident in the group with the factor V Leiden mutation who used oral contraceptives. We noted a high response in all variables (prothrombin fragment 1 and 2, TAT, and D-dimer) in four of 63 (6.3%) volunteers after the flight, but in no-one after either of the control situations. INTERPRETATION Activation of coagulation occurs in some individuals after an 8-h flight, indicating an additional mechanism to immobilisation underlying air travel related thrombosis.

Travel-Related Venous Thrombosis: Results from a Large Population-Based Case Control Study (MEGA Study)

Background Recent studies have indicated an increased risk of venous thrombosis after air travel. Nevertheless, questions on the magnitude of risk, the underlying mechanism, and modifying factors remain unanswered. Methods and Findings We studied the effect of various modes and duration of travel on the risk of venous thrombosis in a large ongoing case-control study on risk factors for venous thrombosis in an unselected population (MEGA study). We also assessed the combined effect of travel and prothrombotic mutations, body mass index, height, and oral contraceptive use. Since March 1999, consecutive patients younger than 70 y with a first venous thrombosis have been invited to participate in the study, with their partners serving as matched control individuals. Information has been collected on acquired and genetic risk factors for venous thrombosis. Of 1,906 patients, 233 had traveled for more than 4 h in the 8 wk preceding the event. Traveling in general was found to increase the risk of venous thrombosis 2-fold (odds ratio [OR] 2.1; 95% confidence interval [CI] 1.5–3.0). The risk of flying was similar to the risks of traveling by car, bus, or train. The risk was highest in the first week after traveling. Travel by car, bus, or train led to a high relative risk of thrombosis in individuals with factor V Leiden (OR 8.1; 95% CI 2.7–24.7), in those who had a body mass index of more than 30 kg/m2 (OR 9.9; 95% CI 3.6–27.6), in those who were more than 1.90 m tall (OR 4.7; 95% CI 1.4–15.4), and in those who used oral contraceptives (estimated OR > 20). For air travel these synergistic findings were more apparent, while people shorter than 1.60 m had an increased risk of thrombosis after air travel (OR 4.9; 95% CI 0.9–25.6) as well. Conclusions The risk of venous thrombosis after travel is moderately increased for all modes of travel. Subgroups exist in which the risk is highly increased.

Multisystem Morbidity and Mortality in Cushing's Syndrome: A Cohort Study

CONTEXT Cushings syndrome (CS) is associated with hypercoagulability, insulin resistance, hypertension, bone loss, and immunosuppression. To date, no adequately large cohort study has been performed to assess the multisystem effects of CS. OBJECTIVE We aimed to examine the risks for mortality, cardiovascular disease, fractures, peptic ulcers, and infections in CS patients before and after treatment. DESIGN Population-based cohort study. SETTING Source population was the entire population of Denmark (1980 to 2010). Data were obtained from the Danish National Registry of Patients and the Danish Civil Registration System. PATIENTS Benign CS of adrenal or pituitary origin and a matched population comparison cohort were included. OUTCOME MEASURES We used Cox regression, and computed hazard ratios (HR) with 95% confidence intervals (95% CI). Morbidity was investigated in the 3 years before diagnosis; morbidity and mortality were assessed during complete follow-up after diagnosis and treatment. RESULTS Included were 343 CS patients and 34 300 controls. Mortality was twice as high in CS patients (HR 2.3, 95%CI 1.8-2.9) compared with controls. Patients with CS were at increased risk for venous thromboembolism (HR 2.6, 95%CI 1.5-4.7), myocardial infarction (HR 3.7, 95%CI 2.4-5.5), stroke (HR 2.0, 95%CI 1.3-3.2), peptic ulcers (HR 2.0, 95%CI 1.1-3.6), fractures (HR 1.4, 95%CI 1.0-1.9), and infections (HR 4.9, 95%CI 3.7-6.4). This increased multimorbidity risk was present before diagnosis. Mortality and risk of myocardial infarction remained elevated during long-term follow-up. Mortality and risks for acute myocardial infarction, venous thromboembolism, stroke, and infections were similarly increased in adrenal and pituitary CS. CONCLUSIONS Despite the apparently benign character of the disease, CS is associated with clearly increased mortality and multisystem morbidity, even before diagnosis and treatment.

Risk factors for venous thrombosis – current understanding from an epidemiological point of view

Epidemiological research throughout the last 50 years has provided the long list of risk factors for venous thrombosis that are known today. Although this has advanced our current understanding about the aetiology of thrombosis, it does not give us all the answers: many people have several of these risk factors but never develop thrombosis; others suffer from thrombosis but have none. In this review, we discuss how risk factors for venous thrombosis can be interpreted with use of several epidemiological models. We comment on how to explain why risk factors for first venous thrombosis differ from recurrent venous thrombosis, and use a causal model to better understand risk of first and recurrent venous thrombosis.

Use of glucocorticoids and risk of venous thromboembolism: A nationwide population-based case-control study

IMPORTANCE Excess endogenous cortisol has been linked to venous thromboembolism (VTE) risk, but whether this relationship applies to exogenous glucocorticoids remains uncertain. Because the prevalence of glucocorticoid use and the incidence of VTE are high, an increased risk of VTE associated with glucocorticoid use would have important implications. BACKGROUND To examine the association between glucocorticoid use and VTE. DESIGN Population-based case-control study using nationwide databases. SETTING Denmark (population 5.6 million). PARTICIPANTS We identified 38,765 VTE cases diagnosed from January 1, 2005, through December 31, 2011, and 387,650 population controls included through risk-set sampling and matched by birth year and sex. The VTE diagnosis date for the case was the index date for cases and matched controls. EXPOSURE We classified individuals who filled their most recent glucocorticoid prescription 90 days or less, 91 to 365 days, and more than 365 days before the index date as present, recent, and former users, respectively. Present users were subdivided into new (first-ever prescription 90 days or less before the index date) and continuing users (others). MAIN OUTCOMES AND MEASURES We used conditional logistic regression adjusted for VTE risk factors to estimate incidence rate ratios (IRRs) and 95% CIs for glucocorticoid users vs nonusers. RESULTS Systemic glucocorticoids increased VTE risk among present (adjusted IRR, 2.31; 95% CI, 2.18-2.45), new (3.06; 2.77-3.38), continuing (2.02; 1.88-2.17), and recent (1.18; 1.10-1.26) users but not among former users (0.94; 0.90-0.99). The adjusted IRR increased from 1.00 (95% CI, 0.93-1.07) for a prednisolone-equivalent cumulative dose of 10 mg or less to 1.98 (1.78-2.20) for more than 1000 to 2000 mg, and to 1.60 (1.49-1.71) for doses higher than 2000 mg. New use of inhaled (adjusted IRR, 2.21; 95% CI, 1.72-2.86) and intestinal-acting (2.17; 1.27-3.71) glucocorticoids also increased VTE risk. CONCLUSIONS AND RELEVANCE The risk of VTE is increased among glucocorticoid users. Although residual confounding may partly explain this finding, we consider a biological mechanism likely because the association followed a clear temporal gradient, persisted after adjustment for indicators of severity of underlying disease, and existed also for noninflammatory conditions. Hence, our observations merit clinical attention.

Elevated endogenous thrombin potential is associated with an increased risk of a first deep venous thrombosis but not with the risk of recurrence

Measurement of the thrombin generating potential could provide a method for quantifying the composite effect of multiple risk factors. This study assessed the risk of a first as well as a recurrent venous thrombotic event associated with an increased endogenous thrombin potential (ETP). Analyses were performed in 360 patients and 404 control subjects of the Leiden Thrombophilia Study. The ETP was measured directly using a fluorogenic assay (ThrombinoscopeTM). Individuals with an increased ETP, i.e. above 90th percentile measured in control subjects (>2109·0 nM·min) had a 1·5‐fold [95% confidence interval (CI): 0·9–2·3] increased risk of a first deep venous thrombosis. The risk was more pronounced after the analysis was restricted to idiopathic thromboses, i.e. 1·7‐fold (95% CI: 1·0–2·8). Overall, the hazard ratio of a recurrent thrombotic event associated with a high ETP, adjusted for age, sex and oral anticoagulant use was 1·1 (95% CI: 0·5–2·2). Thus, a high ETP was not associated with an increased relative risk of recurrent venous thrombosis. At present, the clinical relevance of the thrombin generation assay in predicting recurrent venous thrombosis remains uncertain.