Discharge from the emergency department and outpatient clinic in cancer patients with acute symptomatic and incidental pulmonary embolism: A multicenter retrospective cohort study.

BACKGROUND: It is unclear how often cancer patients with acute pulmonary embolism (PE) are discharged from the emergency department (ED) or outpatient clinic and whether direct discharge is safe. We assessed treatment setting and early safety outcomes in cancer patients with acute symptomatic and incidental PE. METHODS: Cancer patients diagnosed with PE at the ED or outpatient clinic between August 2017 and May 2021 were included in Four Cities VTE Cancer, a Dutch multicenter retrospective cohort study. The main outcome was direct discharge versus hospitalization. Safety outcomes were cumulative 14-day mortality and PE-related readmission incidences. RESULTS: We included 602 patients (median age 71 years; 49.5 % female) of whom 285 (47.3 %) were discharged directly and 317 (52.7 %) were hospitalized. The cumulative 14-day mortality incidence was 0.7 % (95 % CI, 0.1-2.4 %) in patients discharged directly and 9.0 % (95 % CI, 6.2-12.5 %) in those hospitalized. The cumulative 14-day PE-related readmission incidence was 1.8 % (95 % CI, 0.7-3.9 %) and 1.4 % (95 % CI, 0.5-3.3 %) in directly discharged and hospitalized patients, respectively. Of the 220 patients with incidental PE, 180 (81.8 %) were discharged directly compared to 105 of 382 (27.5 %) patients with symptomatic PE (P < 0.001). Mortality and readmission incidences in symptomatic and incidental PE were consistent with the main analysis. CONCLUSIONS: About 28 % and 82 % of cancer patients with symptomatic or incidental PE, respectively, were discharged directly, with low 14-day mortality and PE-related readmission incidences. These data underline the need for PE risk stratification in oncological populations and suggest that clinicians successfully identify a proportion of patients in whom direct discharge is safe.

Treatment of arterial calcification in patients with chronic limb threatening ischemia with etidronate: protocol of an investigator-initiated multicenter, double blind, placebo-controlled, randomized clinical trial.

BACKGROUND: Pathologic studies have shown that in patients with critical limb threatening ischaemia (CLTI) medial arterial calcifications are frequently found and may be responsible for aggravating the disease. These extensive calcifitcations are found not only in arteries of the leg but also in the coronary arteries and the aorta. The progression of these calcifications is fast and they stiffen the vessel wall and may thus increase the cardiovascular risk. Reduction of progression of calcification may not only reduce the burden of CLTI but may also reduce the high residual cardiovascular risk. Medial calcifications have been halted by etidronate in other trials. Its potential to reduce the burden from peripheral vascular disease in CLTI and residual cardiovascular risk remains to be established. METHODS: This is an investigator-initiated multicenter, double blind, placebo-controlled, randomized trial comparing the effects of etidronate versus placebo in patients with CLTI. Subjects will be randomized to either treatment with etidronate for 12 months (cyclical 20 mg/kg for 2 weeks on and 10 weeks off) orally or placebo for 12 months (in a similar routine). The primary endpoint is the change in arterial calcification as quantified by CT-scan. Secondary endpoints are the number of amputations above and below the ankle, mortality, number of vascular interventions and quality of life. DISCUSSION: Up to now, the inert end stage of vascular disease in patients with CLTI, has been considered calcification of vessel walls. We believe there is reason to reverse causation and hypothesize that calcification causes vascular disease. This reversal can be proven in a clinical trial if halting the calcification process improves the outcome of the patient. Therefore we use etidronate, a bisphosphate that has proven to stop the calcification in several rare monogenetic calcifying diseases. We aim to perform this mechanistic proof-of-concept study hopefully leading to a clinical outcome study later on.

Effect of an interactive, educational app about venous thromboembolism and anticoagulation on patient satisfaction: A randomized controlled trial.

BACKGROUND: Adequate patient education is essential for patients to engage in shared decision-making when deciding to stop or continue anticoagulation after 3 months for venous thromboembolism (VTE). Our objectives were to evaluate the effect of an interactive, educational app on patients' level of satisfaction with information, perceived level of knowledge, decisional conflict and extent of shared decision-making when deciding on treatment duration of VTE. MATERIALS AND METHODS: This randomized controlled trial in 1 academic and 3 general Dutch hospitals included adult patients diagnosed with VTE without malignancy or prolonged anticoagulation for other indications. Patients were randomized in 1:1 ratio to receive the app (intervention group) in addition to hospital-specific standard of care. The app, created for this study, contains information on VTE and anticoagulation on an interactive timeline. In the week preceding the consultation when treatment duration is decided, patients were provided with daily videos using push notifications. Outcomes were assessed through self-reported questionnaires at baseline, 1-2 days before and 1 day after consultation. Data were analyzed using t-tests and linear mixed models for repeated measurements. RESULTS: Data of 56 patients were analyzed (mean age 57 ± 13; 27% female). On a numeric rating scale from 0 to 10, patients who received the app were 0.9 points (95%CI 0.0-1.7; p 0.04) more satisfied with the provided information. Patients who received the app experienced significantly less decisional conflict. No differences in other outcomes were observed. CONCLUSIONS: An educational app about VTE and anticoagulation increases patients' satisfaction and reduces decisional conflict when deciding on treatment duration of VTE. This study was registered in the Netherlands Trial Register (NL7037).

Sex-specific performance of pre-imaging diagnostic algorithms for pulmonary embolism.

Essentials Decision rules for pulmonary embolism are used indiscriminately despite possible sex-differences. Various pre-imaging diagnostic algorithms have been investigated in several prospective studies. When analysed at an individual patient data level the algorithms perform similarly in both sexes. Estrogen use and male sex were associated with a higher prevalence in suspected pulmonary embolism. SUMMARY: Background In patients suspected of pulmonary embolism (PE), clinical decision rules are combined with D-dimer testing to rule out PE, avoiding the need for imaging in those at low risk. Despite sex differences in several aspects of the disease, including its diagnosis, these algorithms are used indiscriminately in women and men. Objectives To compare the performance, defined as efficiency and failure rate, of three pre-imaging diagnostic algorithms for PE between women and men: the Wells rule with fixed or with age-adjusted D-dimer cut-off, and a recently validated algorithm (YEARS). A secondary aim was to determine the sex-specific prevalence of PE. Methods Individual patient data were obtained from six studies using the Wells rule (fixed D-dimer, n = 5; age adjusted, n = 1) and from one study using the YEARS algorithm. All studies prospectively enrolled consecutive patients with suspected PE. Main outcomes were efficiency (proportion of patients in which the algorithm ruled out PE without imaging) and failure rate (proportion of patients with PE not detected by the algorithm). Outcomes were estimated using (multilevel) logistic regression models. Results The main outcomes showed no sex differences in any of the separate algorithms. With all three, the prevalence of PE was lower in women (OR, 0.66, 0.68 and 0.74). In women, estrogen use, adjusted for age, was associated with lower efficiency and higher prevalence and D-dimer levels. Conclusions The investigated pre-imaging diagnostic algorithms for patients suspected of PE show no sex differences in performance. Male sex and estrogen use are both associated with a higher probability of having the disease.

The YEARS algorithm for suspected pulmonary embolism: shorter visit time and reduced costs at the emergency department.

Essentials The YEARS algorithm was designed to simplify the diagnostic workup of suspected pulmonary embolism. We compared emergency ward turnaround time of YEARS and the conventional algorithm. YEARS was associated with a significantly shorter emergency department visit time of ˜60 minutes. Treatment of pulmonary embolism was initiated 53 minutes earlier with the YEARS algorithm SUMMARY: Background Recently, the safety of the YEARS algorithm, designed to simplify the diagnostic work-up of pulmonary embolism (PE), was demonstrated. We hypothesize that by design, YEARS would be associated with a shorter diagnostic emergency department (ED) visit time due to simultaneous assessment of pre-test probability and D-dimer level and reduction in number of CT scans. Aim To investigate whether implementation of the YEARS diagnostic algorithm is associated with a shorter ED visit time compared with the conventional algorithm and to evaluate the associated cost savings. Methods We selected consecutive outpatients with suspected PE from our hospital included in the YEARS study and ADJUST-PE study. Different time-points of the diagnostic process were extracted from the to-the-minute accurate electronic patients' chart system of the ED. Further, the costs of the ED visits were estimated for both algorithms. Results All predefined diagnostic turnaround times were significantly shorter after implementation of YEARS: patients were discharged earlier from the ED; 54 min (95% CI, 37-70) for patients managed without computed tomography pulmonary angiography (CTPA) and 60 min (95% CI, 44-76) for the complete study population. Importantly, patients diagnosed with PE by CTPA received the first dose of anticoagulants 53 min (95% CI, 22-82) faster than those managed according to the conventional algorithm. Total costs were reduced by on average €123 per visit. Conclusion YEARS was shown to be associated with a shorter ED visit time compared with the conventional diagnostic algorithm, leading to faster start of treatment in the case of confirmed PE and savings on ED resources.

Combination of Pulmonary Embolism Rule-out Criteria and YEARS Algorithm in a European Cohort of Patients with Suspected Pulmonary Embolism.

BACKGROUND: Both the YEARS algorithm and the pulmonary embolism (PE) rule-out criteria (PERC) were created to exclude PE with limited diagnostic tests. A diagnostic strategy combining both scores might save additional computed tomography pulmonary angiography (CTPA) scans, but they have never been evaluated in conjunction. AIM: The aim of this study was to determine the safety and efficiency of combining YEARS and PERC in a single diagnostic strategy for suspected PE. METHODS: The PERC rule was assessed in 1,316 consecutive patients with suspected PE who were managed according to YEARS. We calculated the absolute difference (with 95% confidence interval [CI]) in failure rate and the number of 'saved' CTPAs for the scenario that PE would have been ruled out without CTPA in the absence of all PERC items. RESULTS: Using the YEARS algorithm, PE was diagnosed in 189 patients (14%), 680 patients (52%) were managed without CTPA and the 3-month rate of venous thromboembolism in patients in whom PE was ruled out was 0.44% (95% CI: 0.19-1.0). Only 6 of 154 patients (3.9%; 95% CI: 1.4-8.2) with no YEARS items who were referred for CTPA would have been PERC negative, of whom none were diagnosed with PE at baseline or during follow-up (0%; 95% CI: 0-64). Applying PERC before YEARS in all patients would have led to a failure rate of 1.42% (95% CI: 0.87-2.3%), 0.98% (95% CI: 0.17-1.9) more than shown in patients managed by YEARS. CONCLUSION: Combining YEARS with PERC would have yielded only a modest improvement of efficiency in patients without a YEARS item and an unacceptable failure rate in patients with ≥ 1 YEARS item.

No added value of the age-adjusted D-dimer cut-off to the YEARS algorithm in patients with suspected pulmonary embolism.

Essentials Imaging is warranted in the majority of patients to confirm or rule out pulmonary embolism (PE). The age-adjusted D-dimer (ADJUST) reduced the number of required imaging tests in patients ≥ 50 years. The YEARS algorithm was designed to improve the efficiency in patients with suspected PE. There was no added value of implementing ADJUST in the YEARS algorithm in our cohort. SUMMARY: Background The YEARS algorithm was designed to simplify the diagnostic work-up of pulmonary embolism (PE) and to reduce the number of necessary computed tomography pulmonary angiography (CTPA) scans. An alternative strategy to reduce the number of CTPAs is the age-adjusted D-dimer cut-off (ADJUST) in patients aged 50 years or older. We aimed to investigate whether a combination of both diagnostic strategies might save additional CTPAs. Methods The YEARS algorithm consists of three items (clinical signs of deep venous thrombosis, hemoptysis, 'PE most likely diagnosis') with simultaneous D-dimer testing using a pre-test dependent threshold. We performed a post hoc analysis in 3465 patients managed according to YEARS to compare the number of patients managed without CTPA scans and associated diagnostic failures in hypothetical scenarios with different YEARS-ADJUST combinations. Results Following the YEARS algorithm, 1651 patients (48%) were managed without CTPA; PE was diagnosed in 456 (13%) patients at baseline and 18 patients with initial normal testing suffered venous thromboembolism (VTE) during 3-month follow-up (failure rate 0.61%; 95% confidence interval [CI], 0.36-0.96). If ADJUST had been fully integrated in YEARS, 1627 patients (47%) would have been managed without CTPA (absolute decrease of 0.69%; 95% CI -1.7 to 3.0), at cost of four additional missed PE diagnoses at baseline, for a projected 3-month VTE failure rate of 0.75% (95% CI, 0.49-1.13). None of the other studied scenarios showed relevant improvements in efficiency as well, but all led to more missed diagnoses. Conclusion In our cohort, there was no added value of implementing ADJUST in the YEARS algorithm.

Use of clinical prediction rules and D-dimer tests in the diagnostic management of pregnant patients with suspected acute pulmonary embolism.

Because pregnant women have an increased risk of venous thromboembolism (VTE) and at the same time normal pregnancy is associated with symptoms, mimicking those present in the setting of acute pulmonary embolism (PE), the latter diagnosis is frequently suspected in this patient category. Since imaging tests expose both mother and foetus to ionizing radiation, the ability to rule out PE based on non-radiological diagnostic tests is of paramount importance. However, clinical decision rules have only been scarcely evaluated in the pregnant population with suspected PE, while D-dimer levels lose diagnostic accuracy due to a physiological increase during normal pregnancy. Consequently, clinical guidelines provide contradicting and weak recommendations on this subject and the optimal diagnostic strategy remains highly debated. With this systematic review, we aimed to summarize current evidence on the safety and efficacy of clinical decision rules and biomarkers used in the diagnostic management of suspected acute PE in pregnant patients.

What role do coagulation disorders play in the pathogenesis of leptospirosis?

Leptospirosis is a zoonosis of worldwide distribution, spread by the urine of infected animals. It is a major public health problem, especially in developing countries, where circumstances for transmission are most favourable. The clinical picture varies from mild disease to a severe illness with haemostatic derangements and multiorgan failure eventually leading to death. Although the haemorrhagic complications of severe disease are serious, the pathophysiology is scarcely elucidated. The complex mechanisms involved in inflammation-induced coagulation activation are extensively studied in various infectious diseases, i.e. Gram-negative sepsis. Tissue factor-mediated coagulation activation, impairment of anticoagulant and fibrinolytic pathways in close concert with the cytokine network are thought to be important. But for human leptospirosis, data are limited. Because of the growing interest in this field, the impact of leptospirosis, and the availability of new therapeutic strategies, we reviewed the evidence regarding the role of coagulation in leptospirosis and provide suggestions for future research.

Increased PAI-1 plasma levels and risk of death from dengue: no association with the 4G/5G promoter polymorphism.

BACKGROUND: Dengue virus infected patients have high plasminogen activator inhibitor type I (PAI-1) plasma concentrations. Whether the insertion/deletion (4G/5G) polymorphism in the promotor region of the PAI-1 gene is associated with increased PAI-1 plasma concentrations and with death from dengue is unknown. We, therefore, investigated the relationship between the 4G/5G polymorphism and PAI-1 plasma concentrations in dengue patients and risk of death from dengue. METHODS: A total of 194 patients admitted to the Dr. Kariadi Hospital in Semarang, Indonesia, with clinical suspected severe dengue virus infection were enrolled. Blood samples were obtained on day of admission, days 1, 2 and 7 after admission and at a 1-month follow-up visit. Plasma concentrations of PAI-1 were measured using a sandwich ELISA kit. The PAI-1 4G/5G polymorphism was typed by allele-specific PCR analysis. RESULTS: Concentrations of PAI-1 on admission and peak values of PAI-1 during admission were higher than the values measured in healthy controls. Survival was significantly worse in patients with PAI-1 concentrations in the highest tertile (at admission: OR 4.7 [95% CI 0.9-23.8], peak value during admission: OR 6.3 [95%CI 1.3-30.8]). No association was found between the PAI-1 4G/5G polymorphism, and PAI-1 plasma concentrations, dengue disease severity and mortality from dengue. CONCLUSION: These data suggest that the 4G/5G polymorphism has no significant influence on PAI-1 concentrations in dengue virus infected patients and is not associated with the risk of death from dengue. Other factors contributing to the variability of PAI-1 plasma concentrations in patients with dengue need to be explored.

Population pharmacokinetics of lopinavir in combination with ritonavir in HIV-1-infected patients.

AIMS: To develop a population pharmacokinetic model for lopinavir in combination with ritonavir, in which the interaction between both drugs was characterized, and in which relationships between patient characteristics and pharmacokinetics were identified. METHODS: The pharmacokinetics of lopinavir in combination with ritonavir were described using NONMEM (version V, level 1.1). First, ritonavir data were fitted to a previously developed model to obtain individual Bayesian estimates of pharmacokinetic parameters. Hereafter, an integrated model for the description of the pharmacokinetics of lopinavir with ritonavir was designed. RESULTS: From 122 outpatients 748 lopinavir and 748 ritonavir plasma concentrations were available for analysis. The interaction between the drugs was described by a time-independent inverse relationship between the exposure to ritonavir over a dosing-interval and the apparent clearance (CL/F) of lopinavir. The model parameters volume of distribution and absorption rate constant were 61.6 l (95% prediction interval (PI) 22.4, 83.7) and 0.564 h(-1) (95% PI 0.208, 0.947), respectively. The model yielded a theoretical value for the CL/F of lopinavir without ritonavir of 14.8 l h(-1) (95%PI 12.1, 20.1), which translates to a value of 5.73 l h(-1) in the presence of ritonavir. The only factor with significant effect on the pharmacokinetics was concurrent use of non-nucleoside reverse transcriptase inhibitors (NNRTI), which increased the CL/F of lopinavir by 39% (P < 0.001). CONCLUSIONS: We have developed a model that has defined a time-independent inverse relationship between the exposure to ritonavir and the CL/F of lopinavir, and provided an adequate description of the pharmacokinetic parameters for the latter. Concomitant use of the NNRTIs efavirenz and nevirapine increased the CL/F of lopinavir.

[Acute respiratory tract infections and acute coronary syndromes]. / Acute luchtweginfecties en acute coronaire syndromen.

Epidemiological research indicates a correlation between respiratory-tract infections and acute cardiovascular events. Chronic infections have been linked to the development of atherosclerosis. As a result of chronic infections a prolonged and elevated inflammatory activity arises. Inflammation and the associated vessel-wall damage play an important role in the pathophysiology of atherosclerosis. Acute infections have been linked to a transient increased risk of unstable angina pectoris and an acute myocardial infarct. The consequence of acute infections is a systemic inflammatory response which results in changes in the atherosclerotic plaque, thrombotic activation and a prothrombotic condition. The inflammatory response and prothrombotic condition reinforce each other. This can result in coagulation on ruptured atherosclerotic plaques and erosions in the vessel wall, which can give rise to the sudden constriction or blockage of coronary arteries.

Non-invasive diagnostic work-up of patients with clinically suspected pulmonary embolism; results of a management study.

BACKGROUND: Clinicians often deviate from the recommended algorithm for the diagnosis of pulmonary embolism consisting of ventilation-perfusion scintigraphy and pulmonary angiography. OBJECTIVES: To assess the safety and feasibility of a diagnostic algorithm which reduces the need for lung scintigraphy and avoids the use of angiography. PATIENTS AND METHODS: Consecutive patients with a clinical suspicion of pulmonary embolism were prospectively investigated according to an algorithm in which the diagnosis of pulmonary embolism was excluded after a low clinical probability estimate and a normal d-dimer test result, a normal perfusion scintigraphy result, or a non-high probability scintigraphy result in combination with normal serial ultrasonography of the legs. In these patients anticoagulant treatment was withheld and they were followed up for 3 months to record possible thromboembolic events. During the study period, 923 consecutive patients were seen, of whom 292 were excluded because of predefined criteria. RESULTS: Of the 631 included patients, the diagnosis was refuted on the basis of a low clinical probability estimate and a normal d-dimer test result (95 patients), normal perfusion scintigraphy (161 patients) and non-high probability lung scintigraphy followed by normal serial ultrasonography (210 patients). Of these 466 patients, venous thromboembolic complications during follow-up occurred in six (complication rate 1.3%, 95% confidence interval 0.5, 2.8). The diagnostic protocol was completed in 92% of all included patients. CONCLUSION: The diagnosis of pulmonary embolism can be safely ruled out by a non-invasive algorithm consisting of d-dimer testing combined with a clinical probability estimate, lung scintigraphy, or serial ultrasonography of the legs (in case of non-diagnostic lung scintigraphy).

Dengue: an arthropod-borne disease of global importance.

Dengue viruses cause a variable spectrum of disease that ranges from an undifferentiated fever to dengue fever to the potentially fatal dengue shock syndrome. Due to the increased incidence and geographical distribution of dengue in the last 50 years, dengue is becoming increasingly recognised as one of the world's major infectious diseases. This article will review clinical and diagnostic aspects of dengue virus infections. It also presents our current knowledge of the pathophysiology of severe dengue and addresses the importance of dengue virus infections in those travelling to parts of the world where dengue is endemic.

Evaluation of clinical pharmacist interventions on drug interactions in outpatient pharmaceutical HIV-care.

OBJECTIVE: To evaluate the usefulness of intervention in drug interactions of antiretroviral drugs with coadministered agents by a clinical pharmacist in outpatient HIV-treatment. METHODS: The study design included two intervention arms (A and B), which were both preceded by a control observation period. In arm A, a complete list of the currently used drugs, extracted from pharmacy records was provided to the treating physician. In arm B the same list was provided but with a notification when a drug interaction was present and an advice how to handle this. The infectious disease specialist obtained the information before the patient's visit to the outpatient clinic (time point 0). Three months prior (time point -3) and 3 months after (time point +3) the intervention, pharmacy records were also screened for drug interactions. The number of drug interactions (total and per patient) was determined at the three different time points (-3, 0, +3). In addition, drug interactions encountered at time points -3 and 0 were checked for their presence at time points 0 and +3, respectively, for both intervention arms. RESULTS: Arms A and B included 115 and 105 patients, respectively. Patient characteristics of both intervention arms were similar at time point 0. The number of interactions and the number of patients with interactions were similar in both intervention arms at time point 0. There were 42 and 40 potential drug interactions in 30 and 24 patients in arms A and B, respectively. The reduction in the number of interactions per patient over time and after intervention was small but significant, and was equal in both intervention arms. The advice of the clinical pharmacist had thus no additional value. CONCLUSION: Both interventions were effective in reducing the number of drug interactions per patient. The advice of a clinical pharmacist was, however, redundant in the studied setting.

Is clinical outcome of dengue-virus infections influenced by coagulation and fibrinolysis? A critical review of the evidence.

Despite efforts to elucidate the pathogenesis of dengue fever, the progression into severe disease remains poorly understood. In-vitro findings suggest that coagulopathy and disturbances in fibrinolysis have a pivotal role in the pathophysiology. If disturbances in these processes are predictive of clinical outcome in this disease, there could be important consequences for both diagnosis and treatment. We have critically reviewed publications on this topic to assess whether there is an association between activation of coagulation and fibrinolysis and clinical outcome of dengue-virus infections. In general, the selected studies showed activation of both the coagulation and fibrinolytic systems in this infection. The activation was more pronounced in severe infections and in cases with a poor clinical outcome. However, the findings were not consistent, and owing to a lack of detailed information on characteristics of patients, disease, and study design, we could not ascertain whether inconsistencies were caused by differences in these characteristics, selection bias, or confounding factors. We conclude that an association between activation of coagulation and fibrinolysis and clinical outcome of dengue-virus infections is conceivable but has been inadequately assessed and that methodologically sound studies, complemented with complete and reliable reporting, are needed to show whether there is a true association.

Kinetics of dengue virus-specific serum immunoglobulin classes and subclasses correlate with clinical outcome of infection.

The kinetics of dengue virus (DEN)-specific serum immunoglobulin classes (immunoglobulin M [IgM] and IgA) and subclasses (IgG1 to IgG4) were studied in patients suffering from dengue fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS). Serum samples from non-DEN febrile patients were included as controls. IgM, IgG1, and IgG3 serum antibodies were the predominant immunoglobulins throughout the course of illness in all three patient groups. In contrast, IgA antibodies were significantly higher in the acute phase in DSS patients compared to those in DF patients (P < 0.05). The levels of IgG1 differed significantly between patients with DF and those with DHF and DSS (P < 0.05). A significant difference was also found in IgG3 levels between DF patients and DHF patients (P < 0.05) but not between DF patients and DSS patients. Finally, levels of IgG4 antibodies differed significantly between DF patients and DSS patients (P < 0.05). Collectively, these data show that increased levels of DEN-specific IgA, IgG1, and IgG4 serum antibodies are risk markers for the development of DHF and DSS and that their measurement may provide valuable guidance for early therapeutic intervention.

Activation of coagulation factor XI, without detectable contact activation in dengue haemorrhagic fever.

A prospective cohort study was performed in 50 patients with dengue haemorrhagic fever (DHF) to determine the potential role of the contact activation system and factor XI activation (intrinsic pathway) in the coagulation disorders in DHF. To establish whether TAFI (thrombin-activatable fibrinolysis inhibitor) was involved in the severity of the coagulation disorders, the TAFI antigen and activity levels were also determined. Markers of contact activation (kallikrein--C1-inhibitor complexes), the intrinsic pathway of coagulation (factor XIa--C1-inhibitor complexes) and TAFI were measured and correlated to thrombin generation markers (thrombin--anti-thrombin complexes (TAT), prothrombin fragment 1+2 (F1+2)) and a marker for fibrinolysis [plasmin--alpha 2--anti-plasmin complexes (PAP)]. Activation of the intrinsic pathway of coagulation was clearly demonstrated by elevated levels of factor XIa--C1-inhibitor complexes, without evidence of contact activation, reflected by undetectable kallikrein--C1-inhibitor complexes. Both TAFI antigen and activity levels were decreased in all patients, which may contribute to the severity of bleeding complications in DHF because of the impaired capacity of the coagulation system to protect the fibrin clot from fibrinolysis. These findings in a human viral infection model are in accordance with earlier findings in bacterial sepsis.