Ellen Brodin

Association of Mild to Moderate Chronic Kidney Disease With Venous Thromboembolism Pooled Analysis of Five Prospective General Population Cohorts

Background— Recent findings suggest that chronic kidney disease (CKD) may be associated with an increased risk of venous thromboembolism (VTE). Given the high prevalence of mild-to-moderate CKD in the general population, in depth analysis of this association is warranted. Methods and Results— We pooled individual participant data from 5 community-based cohorts from Europe (second Nord-Trondelag Health Study [HUNT2], Prevention of Renal and Vascular End-stage Disease [PREVEND], and the Tromso study) and the United States (Atherosclerosis Risks in Communities [ARIC] and Cardiovascular Health Study [CHS]) to assess the association of estimated glomerular filtration rate (eGFR), albuminuria, and CKD with objectively verified VTE. To estimate adjusted hazard ratios for VTE, categorical and continuous spline models were fit by using Cox regression with shared-frailty or random-effect meta-analysis. A total of 1178 VTE events occurred over 599 453 person-years follow-up. Relative to eGFR 100 mL/min per 1.73 m2, hazard ratios for VTE were 1.29 (95% confidence interval, 1.04–1.59) for eGFR 75, 1.31 (1.00–1.71) for eGFR 60, 1.82 (1.27–2.60) for eGFR 45, and 1.95 (1.26–3.01) for eGFR 30 mL/min per 1.73 m2. In comparison with an albumin-to-creatinine ratio (ACR) of 5.0 mg/g, the hazard ratios for VTE were 1.34 (1.04–1.72) for ACR 30 mg/g, 1.60 (1.08–2.36) for ACR 300 mg/g, and 1.92 (1.19–3.09) for ACR 1000 mg/g. There was no interaction between clinical categories of eGFR and ACR ( P =0.20). The adjusted hazard ratio for CKD, defined as eGFR <60 mL/min per 1.73 m2 or albuminuria ≥30 mg/g, (versus no CKD) was 1.54 (95% confidence interval, 1.15–2.06). Associations were consistent in subgroups according to age, sex, and comorbidities, and for unprovoked versus provoked VTE, as well. Conclusions— Both eGFR and ACR are independently associated with increased risk of VTE in the general population, even across the normal eGFR and ACR ranges. # Clinical Perspective {#article-title-41}Background— Recent findings suggest that chronic kidney disease (CKD) may be associated with an increased risk of venous thromboembolism (VTE). Given the high prevalence of mild-to-moderate CKD in the general population, in depth analysis of this association is warranted. Methods and Results— We pooled individual participant data from 5 community-based cohorts from Europe (second Nord-Trøndelag Health Study [HUNT2], Prevention of Renal and Vascular End-stage Disease [PREVEND], and the Tromsø study) and the United States (Atherosclerosis Risks in Communities [ARIC] and Cardiovascular Health Study [CHS]) to assess the association of estimated glomerular filtration rate (eGFR), albuminuria, and CKD with objectively verified VTE. To estimate adjusted hazard ratios for VTE, categorical and continuous spline models were fit by using Cox regression with shared-frailty or random-effect meta-analysis. A total of 1178 VTE events occurred over 599 453 person-years follow-up. Relative to eGFR 100 mL/min per 1.73 m2, hazard ratios for VTE were 1.29 (95% confidence interval, 1.04–1.59) for eGFR 75, 1.31 (1.00–1.71) for eGFR 60, 1.82 (1.27–2.60) for eGFR 45, and 1.95 (1.26–3.01) for eGFR 30 mL/min per 1.73 m2. In comparison with an albumin-to-creatinine ratio (ACR) of 5.0 mg/g, the hazard ratios for VTE were 1.34 (1.04–1.72) for ACR 30 mg/g, 1.60 (1.08–2.36) for ACR 300 mg/g, and 1.92 (1.19–3.09) for ACR 1000 mg/g. There was no interaction between clinical categories of eGFR and ACR (P=0.20). The adjusted hazard ratio for CKD, defined as eGFR <60 mL/min per 1.73 m2 or albuminuria ≥30 mg/g, (versus no CKD) was 1.54 (95% confidence interval, 1.15–2.06). Associations were consistent in subgroups according to age, sex, and comorbidities, and for unprovoked versus provoked VTE, as well. Conclusions— Both eGFR and ACR are independently associated with increased risk of VTE in the general population, even across the normal eGFR and ACR ranges.

Heparin induces mobilization of osteoprotegerin into the circulation

Heparin treatment may induce osteoporosis by an unknown mechanism. Osteoprotegerin (OPG), a glycoprotein with a heparin-binding site, is a decoy receptor for RANKL which is responsible for osteoclast development. The objective was to investigate the effect of unfractionated heparin (UFH) and lowmolecular-weight heparin (LMWH; dalteparin) on plasma levels of OPG. Twenty-two male students were allocated to the following treatment regimens; A) one bolus of 5,000 IU UFH iv followed by infusion of 450 IU/kg/24 h for 72 hours (n = 7), B) sc administration of LMWH (200 IU/kg) once daily for 72 hours (n = 8), C) sc administration of 100 IU/kg LMWH once (n = 8), D) sc administration of 250 IU/kg UFH once (n = 7), E) control infusion of saline for 12 hours (n = 7). UFH boluses of 5,000 IU were given 4 and 24 hours after cessation of regimens A and B. Bolus injection of UFH iv caused a prompt increase in plasma OPG from 0.68 ng/ml (SD = 0.09) to 1.13 ng/ml (SD = 0.30) (p = 0.003) which declined during the continuous UFH infusion and reached baseline values after 8 hours (regime A). Similar increases in plasma OPG was obtained by repeated UFH boluses after cessation of treatment. Subcutaneous administration of LMWH (200 IU/kg) caused a modest, but significant (p = 0.002) increase in plasma OPG similar to the mobilization by 250 IU/kg UFH sc, but the LMWH treatment caused a three-fold higher anti-Xa activity (p < 0.001). We conclude that UFH causes a more pronounced vascular mobilization of OPG than LMWH, indicating that UFH has a higher affinity for OPG than LMWH.

Increased level of platelet microparticles in survivors of myocardial infarction

Platelet microparticles (PMPs) are highly procoagulant and might therefore be important in the pathogenesis of arterial thrombotic diseases. The aim of this study was to determine plasma levels of PMPs in survivors of myocardial infarction (MI) and their relation to activation of primary (sCD40L) and secondary (thrombin‐antithrombin (TAT) complexes) haemostasis. An observational, population‐based case control study was conducted in 61 MI patients 1–4 years after the MI and 61 age‐matched and sex‐matched healthy controls. PMPs were quantified using an immunoassay that discriminates between small and large PMPs. MI patients had significantly higher total PMPs (314.3 µg/L, 273.1–361.4 µg/L versus 225.8 µg/L, 168.8–273.1 µg/L, p = 0.009) (geometric mean and 95% CI) and larger PMPs (181.3 µg/L, 160.7–204.3 µg/L versus 134.3 µg/L, 104.6–174.9 µg/L) than controls. The differences between groups remained significant after adjustments for use of cardiovascular drugs, body mass index, blood pressure and serum lipids, but were weakened when smoking was included in the analysis. Multiple regression analysis revealed a significant independent association between large PMPs and plasma TAT and soluble CD40 ligand (sCD40L) in MI patients, but not in healthy controls. The independent association between large PMPs and thrombin generation supports the concept that formation of PMPs is important for increased coagulation activation in MI patients.

Elevated levels of platelet microparticles in carotid atherosclerosis and during the postprandial state

BACKGROUND Platelet microparticles (PMPs) possess proatherogenic and procoagulant properties which may play a role in atherogenesis and subsequent thromboembolic complications. The present study was conducted to investigate the possible relationship between carotid atherosclerosis and plasma concentrations of PMPs, and elucidate if plasma levels of PMPs were affected by postprandial hypertriglyceridemia. METHODS AND RESULTS Subjects with ultrasound-assessed carotid atherosclerotic plaques (echogenic; n=20 and echolucent; n=20), assessed by ultrasonography, and subjects without carotid plaques (n=20) were recruited from a population-based study and underwent a standard fat tolerance test. Subjects with carotid plaques had significantly higher levels of large PMPs than subjects without carotid atherosclerotic plaques (96.7+/-50.4 microg/l versus 56.1+/-34.9 microg/l), after adjustments for traditional cardiovascular risk factors and use cardiovascular drugs (p=0.021). Plasma PMPs were not associated with plaque echogenicity. Postprandial hypertriglyceridemia induced a similar increase in plasma PMPs within all groups. Significant correlations were found between an increase in plasma triglycerides and percent elevation in total PMPs (r=0.29, p<0.05) and large PMPs (r=0.34, p<0.01) in the postprandial phase. CONCLUSIONS Individuals with echogenic and echolucent carotid atherosclerotic plaques have statistically significant elevation of large plasma PMPs compared to age/sex-matched normal controls. Postprandial hypertriglyceridemia induces a significant, similar increase in plasma PMPs in individuals with and without carotid atherosclerotic plaques which could be of pathophysiological importance in atherogenesis.

Impact of long-term testosterone treatment on plasma levels of free TFPI and TF-induced thrombin generation ex vivo in elderly men with low testosterone levels

Men have a higher incidence of cardiovascular disease (CVD) than women of similar age, and it has been suggested that testosterone may influence the development of CVD. Recently, we demonstrated that elderly men with low testosterone levels had lower plasma levels of free tissue factor pathway inhibitor (TFPI) Ag associated with shortened tissue factor (TF)-induced coagulation initiation in a population based case-control study. Our hypothesis was that one year of testosterone treatment to physiological levels in elderly men would increase the levels of free TFPI Ag in plasma and have a favorable effect on TF-induced coagulation. Twenty-six men with low testosterone levels (< or =11.0 nM) were randomly assigned to treatment with intramuscular testosterone depot injections (testosterone undecanoate 1,000 mg) or placebo in a double-blinded study. Each participant received a total of five injections, at baseline, 6, 16, 28 and 40 weeks, and TF-induced thrombin generation ex vivo and plasma free TFPI Ag were measured after one year. At the end of the study total and free testosterone levels were significantly higher in the testosterone treated group (14.9 +/- 4.5 nM vs. 8.1 +/- 2.4 nM; p < 0.001, and 363.3 +/- 106.6 pM vs. 187.3 +/- 63.2 pM; p < 0.001, respectively). Testosterone treatment for one year did neither cause significant changes in TF-induced thrombin generation ex vivo nor changes in plasma levels of free TFPI Ag. In conclusion, normalising testosterone levels by testosterone treatment for 12 months in elderly men did not affect TF-induced coagulation or plasma TFPI levels. The potential antithrombotic role of testosterone therapy remains to be elucidated.

Regulation of thrombin generation by TFPI in plasma without and with heparin

The purpose of this study was to investigate the impact of recombinant glycosylated TFPI (rg-TFPI) from BHK cells, nonglycosylated TFPI (r-TFPI) from Escherichia coli, and truncated TFPI (1-161) on thrombin generation (TG) in plasma treated with and without heparin in vitro and ex vivo. Fasting plasma samples were collected from 6 healthy persons. TG was assessed by the calibrated automated thrombography (CAT) method. The addition of increasing concentrations (0-200 ng/mL) of different TFPI caused a 5% to 30% prolongation of lag time for TF (3.0 pM) induced TG, with the most pronounced effect for rg-TFPI and the least pronounced effect for truncated TFPI, but without affecting endogenous thrombin potential (ETP) in TF-induced coagulation. Removal of native TFPI from plasma by anti-TFPI IgG treatment shortened lag time by 35 +/- 4% without affecting ETP. Increasing concentrations (0-200 ng/mL) of various TFPI in the presence of low heparin concentrations (0.1 IU/mL) prolonged lag time and decreased ETP by 25% to 75% with the most prominent effect promoted by glycosylated full-length TFPI. The effect of neutralizing antibodies against TFPI and antithrombin (AT) was studied in plasma in the presence of heparin administered in vitro or ex vivo. The results revealed that TFPI and AT acted in synergy as inhibitors of coagulation in terms of the effect on both initiation (lag time) and propagation (ETP). Our data demonstrated that the CAT assay appropriately assessed the impact of TFPI on initiation and propagation of TG in a physiological plasma milieu with and without heparin. TFPI contributed significantly to regulation of coagulation initiation (lag time). The C-terminal region and, to a lesser extent, glycosylation of the TFPI molecule were essential for its anticoagulant function in the absence and presence of heparin.

Endogenous thrombin potential (ETP) in plasma from patients with AMI during antithrombotic treatment

BACKGROUND The beneficial impact of warfarin in preventing new events after AMI is well established. Decrease in thrombin generation seems to be the key element in anticoagulant treatment. OBJECTIVES The aims were to investigate the effect of warfarin and platelet inhibition on thrombin generation, assessed by the endogenous thrombin potential (ETP), and study the relation between coagulation parameters and ETP in patients with AMI. PATIENTS/METHODS In the present sub-study of the WARIS II trial, patients with AMI were randomly assigned to treatment with aspirin 160 mg/d (n=57), aspirin 75 mg/d and warfarin (INR 2.0-2.5) (n=68) or warfarin (INR 2.8-4.2) (n=61). Fasting blood samples were collected from patients at discharge from hospital and after 6 weeks treatment. RESULTS Correlation analyses showed that both ETP and peak thrombin levels were significantly correlated with Factor VII Ag (r=0.38 and 0.36 respectively, p<0.01 for both) and with F1+2 (r=0.26 and 0.23 respectively, p=0.01 for both) at baseline. Antithrombotic treatment for 6 weeks caused a highly significant inhibition of ETP in patients treated with warfarin (-28%+/-5%, p<0.001), and patients treated with aspirin/warfarin (-24%+/-8%, p=0.04). Similarly, peak thrombin levels were reduced in patients treated with warfarin (-18%+/-7%, p=0.049) and aspirin/warfarin (-19%+/-5%, p=0.029), whereas an increase (12%+/-4%, p=0.029) occurred during aspirin treatment alone. F1+2 levels decreased by 64% and 58% in the warfarin and aspirin/warfarin groups, respectively (p=0.001 for both). CONCLUSIONS In patients with AMI, warfarin significantly reduced the endogenous thrombin generation and the potential to generate thrombin in plasma ex vivo, whereas aspirin alone had no effect on thrombin generation in vivo or ex vivo, assessed by ETP.

COPD and risk of venous thromboembolism and mortality in a general population

The relationship between chronic obstructive pulmonary disease (COPD) and risk of venous thromboembolism (VTE) has been scarcely studied in the general population. We aimed to investigate the association between COPD and risk of VTE and mortality in a population-based cohort. Spirometry was conducted in 8646 males and females, participating in the fifth (2001–02) and sixth (2007–08) surveys of the Tromsø Study. Incident VTE events during follow-up were registered from the date of inclusion to December 31, 2011. Cox-regression models with COPD stages and confounders as time varying covariates were used to calculate hazard ratios with 95% confidence intervals for VTE and all-cause mortality. During a median follow-up of 6.2 years, 215 subjects developed VTE. Subjects with COPD stage III/IV had a two-fold higher risk of secondary VTE compared to subjects with normal airflow (HR 2.05, 95% CI 1.02–4.10). COPD patients, particularly those with stage III/IV disease, with VTE had a higher mortality rate than COPD patients without VTE (50.2% versus 5.6% per year). Our findings suggest that patients with severe COPD may have increased risk of secondary VTE, and that COPD patients with VTE have a higher mortality rate than COPD patients without VTE. Patients with severe COPD may have increased risk of VTE: VTE is associated with a worse prognosis in COPD patients http://ow.ly/Tdd09

Testosterone, Hemostasis, and Cardiovascular Diseases in Men

Men have a higher incidence of cardiovascular disease (CVD) than women, and adverse thrombotic events increase with age. Recent experimental cross-sectional, and case-control studies have shown that testosterone may affect the hemostatic/fibrinolytic system in men in several ways. It has been hypothesized that physiological doses of testosterone would have a beneficial effect on tissue factor-induced thrombin generation and the development of CVD. The search for eternal youth has created a market for testosterone treatment in aging men during the last few years. However, whether testosterone supplementation could be useful in the treatment of testosterone-deficient elderly men is still controversial. The present review focuses on the coagulation system and CVD from the perspective of testosterone.

Coagulation activation in young survivors of myocardial infarction (MI) - a population-based case-control study

Formation of an occlusive thrombus by exposure of tissue factor (TF) to circulating blood and subsequent triggering of coagulation by TF-FVIIa complexes on ruptured atherosclerotic plaques is thought to be a key event in acute MI. Tissue factor pathway inhibitor (TFPI) is a potent inhibitor of TF-induced coagulation by neutralizing FXa and inhibiting the TF-FVIIa complex. A case control study was conducted to investigate the role of coagulation activation in MI. Sixty-two patients with verified MI, 40-60 yrs of age, were recruited into the study and examined 1-4 years after the acute coronary event. Thrombin-antithrombin complex (TAT) was significantly increased in MI patients (8.2 +/- 12.9 microg/l vs. 3.9 +/- 2.6 microg/l, p=0.01). In contrast, FVIIa was lower in MI patients (41 +/- 13 mU/ml vs. 48 +/- 15 mU/ml, p=0.003) accompanied by an increase in plasma free TFPI antigen (20.9 +/- 5.0 ng/ml vs. 19.2 +/- 4.9 ng/ml, p=0.03). Significant trends for increase in triglycerides and total cholesterol across quartiles of free TFPI Ag were found in both groups, whereas HDL cholesterol decreased across quartiles of TFPI among control subjects. The compensatory increase in plasma free TFPI with established lipid and haemostatic risk factors were abrogated in the MI patients. An apparent increase in the basal activation of the coagulation system was observed in young patients with MI. Enhanced coagulation activation was accompanied by a decrease in FVIIa and increase in free TFPI Ag, probably reflecting a modest triggering of TF-induced coagulation in these patients.