Impact of incident myocardial infarction on the risk of venous thromboembolism: the Tromsø Study

How I treat the co-occurrence of venous and arterial thromboembolism: anticoagulation, antiplatelet therapy, or both?

ABSTRACT

Arterial and venous thromboses are classically considered distinct disease states, with arterial thrombosis mediated predominantly by platelets and therefore, treated with antiplatelet therapy, and venous thrombosis mediated by the plasmatic coagulation system and treated with anticoagulation. However, co-occurrence of arterial and venous events is common, and there is increasing evidence of shared risk factors and pathophysiologic overlap. This presents a management challenge: does the patient with venous and arterial thrombosis, require anticoagulation, antiplatelet therapy, or both? Herein, we present a structured approach to the evaluation and management of patients with venous thrombosis who are also at risk for or have a history of an arterial thromboembolic event. We emphasize the importance of defining the indications for antithrombotic therapy, as well as the evaluation of factors that influence both thrombotic and bleeding risk, including disorder-specific and patient-specific factors, as well as the inherent risk balance of antithrombotic therapy regimens. We illustrate this approach in 4 cases, discussing the unique considerations and recent updates in the management of venous thrombosis, acute noncardioembolic ischemic stroke, coronary artery disease and acute myocardial infarction, and peripheral artery disease after revascularization.

Combined effect of high factor VIII levels and high mean platelet volume on the risk of future incident venous thromboembolism

BACKGROUND

High factor VIII (FVIII) levels and large platelets, as reflected by a high mean platelet volume (MPV), are separately associated with increased risk of venous thromboembolism (VTE). Whether the combination of high FVIII levels and large platelets has a supra-additive effect on VTE risk is unknown.

OBJECTIVES

We aimed to investigate the joint effect of high FVIII levels and large platelets, as reflected by high MPV, on the risk of future incident VTE.

METHODS

A population-based nested case-control study with 365 incident VTE cases and 710 controls was derived from the Tromsø study. FVIII antigen levels and MPV were measured in blood samples drawn at baseline. Odds ratios with 95% CIs were estimated across FVIII tertiles (<85%, 85%-108%, and ≥108%) and within predefined MPV strata (<8.5, 8.5-9.5, and ≥9.5 fL).

RESULTS

VTE risk increased linearly across FVIII tertiles (Ptrend < .001) in models adjusted for age, sex, body mass index, and C-reactive protein. In the combined analysis, participants with FVIII levels in the highest tertile and an MPV of ≥9.5 fL (ie, joint exposure) had an odds ratio for VTE of 2.71 (95% CI, 1.44-5.11) compared with those with FVIII levels in the lowest tertile and an MPV of <8.5 fL (reference). In the joint exposure group, 52% (95% CI, 17%-88%) of VTEs were attributable to the biological interaction between FVIII and MPV.

CONCLUSION

Our results suggest that large platelets, as reflected by high MPV, might play a role in the mechanism by which high FVIII level increases the risk of incident VTE.

Investigating the prevalence of and predictive and risk factors for pulmonary embolism in patients with COVID-19 in Nemazee Teaching Hospital

Background

Pulmonary thromboembolism (PTE) is a significant contributing factor to vascular diseases. This study aimed to determine the prevalence of pulmonary thromboembolism and its predisposing factors in patients with COVID-19.

Methods

This cross-sectional study included 284 patients with COVID-19 who were admitted to Nemazee Teaching Hospital (Shiraz, Iran) between June and August 2021. All patients were diagnosed with COVID-19 by a physician based on clinical symptoms or positive polymerase chain reaction (PCR) test results. The collected data included demographic data and laboratory findings. Data were analyzed using the SPSS software. P≤0.05 was considered statistically significant.

Results

There was a significant difference in the mean age between the PTE group and non-PTE group (P=0.037). Moreover, the PTE group had a significantly higher prevalence of hypertension (36.7% vs. 21.8%, P=0.019), myocardial infarction (4.5% vs. 0%, P=0.006), and stroke (23.9% vs. 4.9%, P=0.0001). Direct bilirubin (P=0.03) and albumin (P=0.04) levels significantly differed between the PTE and non-PTE groups. Notably, there was a significant difference in the partial thromboplastin time (P=0.04) between the PTE and non-PTE groups. A regression analysis indicated that age (OR, 1.02; 95% CI, 1.00‒1.004; P=0.005), blood pressure (OR, 2.07; 95% CI, 1.12‒3.85; P=0.02), heart attack (OR, 1.02; 95% CI, 1.28‒6.06; P=0.009), and albumin level (OR, 0.39; 95% CI, 0.16‒0.97; P=0.04) were all independent predictors of PTE development.

Conclusion

Regression analysis revealed that age, blood pressure, heart attack, and albumin levels were independent predictors of PTE.

Impact of the von Willebrand factor-ADAMTS-13 axis on the risk of future venous thromboembolism

BACKGROUND

von Willebrand factor (VWF) and its cleaving protease, ADAMTS-13, form a pivotal axis that regulates hemostasis. However, the role of the VWF-ADAMTS-13 axis in the risk of future venous thromboembolism (VTE) is unknown.

OBJECTIVES

To investigate whether plasma ADAMTS-13 levels and an imbalance with VWF levels, assessed as the VWF/ADAMTS-13 ratio, are associated with the risk of future VTE.

PATIENTS/METHODS

A population-based nested case-control study, comprising 383 incident VTE cases and 780 age- and sex-matched controls, was derived from the Tromsø study cohort (1994-2007). Antigen levels of ADAMTS-13 and VWF were measured in plasma samples obtained at cohort baseline. Odds ratios (ORs) with 95% CIs were estimated according to quartile cutoffs of ADAMTS-13 and VWF/ADAMTS-13 ratio determined in controls.

RESULTS

In age- and sex-adjusted analysis, ADAMTS-13 levels were inversely associated with the VTE risk, with an OR of 1.40 (95% CI, 0.99-1.99) for the lowest vs highest quartiles. The VWF/ADAMTS-13 ratio was linearly associated with the VTE risk (P for trend = .001), with an OR of 1.70 (95% CI, 1.19-2.43) for the highest vs lowest quartiles, and the association was particularly pronounced for unprovoked VTE (OR, 2.81; 95% CI, 1.65-4.81). The ORs were only slightly attenuated after additional adjustments for body mass index and C-reactive protein.

CONCLUSIONS

Lowered ADAMTS-13 levels and an imbalance between ADAMTS-13 and VWF levels, reflected by an increased VWF/ADAMTS-13 ratio, were associated with an increased risk of future VTE. Our findings suggest that the VWF-ADAMTS-13 axis is involved in the pathogenesis of VTE.

Impact of venous thromboembolism on incidence of arterial thromboembolism - An analysis of German outpatient claims data

BACKGROUND

Venous thromboembolism (VTE) and arterial thromboembolism (ATE) are considered as two separate disease-entities. In recent years, studies have reported clear associations between VTE and atherosclerosis. We aimed to evaluate the long-term risk of ATE in VTE patients in comparison to controls without VTE.

METHODS

Nationwide outpatient claims data of all inhabitants with statutory health insurance in Germany were used for secondary data analysis between the years 2011 and 2020. Patients treated in 2013 were stratified by VTE event, and groups were 1:2-matched by age and sex. The hazard for an ATE event in a 5-year follow-up period between patients with and without VTE was calculated with multivariable Cox regression adjusted for age, sex, cardiovascular risk factors, and comorbidities.

RESULTS

Of 69,699,277 individuals treated in the year 2013 by German physicians in outpatient care, in total 686,382 individuals (age 59.8 ± 17.5 years, 65.4 % females) were included comprising 228,794 patients with VTE and 457,588 controls without VTE. VTE patients more often had cardiovascular risk factors (81.6 % vs. 62.2 %) and traditional VTE risk factors. The occurrence of ATE events during follow-up was 1.8 %-points higher in VTE patients in comparison to the controls (9.7 % vs. 7.9 %). VTE events were independently associated with increased occurrence of ATE events within follow-up (HR_adjusted 1.19 [99%CI 1.16-1.23], p < 0.0001).

CONCLUSIONS

Patients with a VTE event have an increased long-term risk for subsequent arterial cardiovascular events. Large prospective cohorts are needed to identify patient subgroups with a very high ATE risk after VTE.

Discovery of protein biomarkers for venous thromboembolism in non-small cell lung cancer patients through data-independent acquisition mass spectrometry

Objective

Non-small cell lung cancer (NSCLC) patients present a high incidence of venous thromboembolism (VTE) with poor prognosis. It is crucial to identify and diagnose VTE early. The study aimed to identify potential protein biomarkers and mechanism of VTE in NSCLC patients via proteomics research.

Methods

Proteomic analysis of the human plasma was performed through data-independent acquisition mass spectrometry for 20 NSCLC patients with VTE, and 15 NSCLC patients without VTE. Significantly differentially expressed proteins were analyzed by multiple bioinformatics method for further biomarker analysis.

Results

A total of 280 differentially expressed proteins were identified in VTE and non-VTE patients, where 42 were upregulated and 238 were downregulated. These proteins were involved in acute-phase response, cytokine production, neutrophil migration and other biological processes related to VTE and inflammation. Five proteins including SAA1, S100A8, LBP, HP and LDHB had significant change between VTE and non-VTE patients, with the area under the curve (AUC) were 0.8067, 0.8308, 0.7767, 0.8021, 0.8533, respectively.

Conclusions

SAA1, S100A8, LBP, HP and LDHB may serve as potential plasma biomarkers for diagnosis VTE in NSCLC patients.

Neutrophil "plucking" on megakaryocytes drives platelet production and boosts cardiovascular disease

Intravascular neutrophils and platelets collaborate in maintaining host integrity, but their interaction can also trigger thrombotic complications. We report here that cooperation between neutrophil and platelet lineages extends to the earliest stages of platelet formation by megakaryocytes in the bone marrow. Using intravital microscopy, we show that neutrophils "plucked" intravascular megakaryocyte extensions, termed proplatelets, to control platelet production. Following CXCR4-CXCL12-dependent migration towards perisinusoidal megakaryocytes, plucking neutrophils actively pulled on proplatelets and triggered myosin light chain and extracellular-signal-regulated kinase activation through reactive oxygen species. By these mechanisms, neutrophils accelerate proplatelet growth and facilitate continuous release of platelets in steady state. Following myocardial infarction, plucking neutrophils drove excessive release of young, reticulated platelets and boosted the risk of recurrent ischemia. Ablation of neutrophil plucking normalized thrombopoiesis and reduced recurrent thrombosis after myocardial infarction and thrombus burden in venous thrombosis. We establish neutrophil plucking as a target to reduce thromboischemic events.

Joint effect of myocardial infarction and obesity on the risk of venous thromboembolism: The Tromsø Study

BACKGROUND

Myocardial infarction (MI) is associated with an increased risk of venous thromboembolism (VTE). Obesity is a recognized risk factor for both MI and VTE. Whether obesity further increases the risk of VTE in MI patients is scarcely investigated.

AIM

To study the joint effect of MI and obesity on the risk of VTE.

METHODS

Study participants (n = 29 410) were recruited from three surveys of the Tromsø Study (conducted in 1994-1995, 2001, and 2007-2008) and followed up through 2014. All incident MI and VTE cases during follow-up were recorded. Cox regression models with MI as a time-dependent variable were used to estimate hazard ratios (HRs) of VTE (adjusted for age and sex) by combinations of MI exposure and obesity status. Joint effects were assessed by calculating relative excess risk and attributable proportion (AP) due to interaction.

RESULTS

During a median of 19.6 years of follow-up, 2090 study participants experienced an MI and 784 experienced a VTE. Among those with MI, 55 developed a subsequent VTE, yielding an overall incidence rate (IR) of VTE of 5.3 per 1000 person-years (95% confidence interval [CI]: 4.1-6.9). In the combined exposure group (MI+/Obesity+), the IR was 11.3 per 1000 person-years, and the adjusted HR indicated a 3-fold increased risk of VTE (HR 3.16, 95% CI: 1.99-4.99) compared to the reference group (MI-/Obesity-). The corresponding AP was 0.46 (95% CI: 0.17-0.74).

CONCLUSIONS

The combination of MI and obesity yielded a supra-additive effect on VTE risk of which 46% of the VTE events were attributed to the interaction.

Plasma lipopolysaccharide-binding protein is a biomarker for future venous thromboembolism: Results from discovery and validation studies

BACKGROUND

Effect-size underestimation impedes biomarker identification. Long follow-up time in prospective studies attenuates effect-size estimates for transient biomarkers, while disease category-specific biomarkers are affected by merging of categories. Venous thromboembolism (VTE) encompasses deep vein thrombosis (DVT) and pulmonary embolism (PE).

OBJECTIVES

(i) To re-analyze untargeted proteomic data to identify biomarker candidates for future VTE that differ between DVT and PE and are attenuated by extended time between sampling and VTE. (ii) To perform targeted candidate validation.

PATIENTS/METHODS

A VTE case-control discovery study and a nested case-control validation study were derived from the general population surveyed in 1994-95. Plasma was obtained at study enrollment, and VTE events were registered until 2007. Untargeted proteomic data were re-analyzed for candidate discovery. Lipopolysaccharide-binding protein (LBP) was validated by enzyme-linked immunosorbent assay.

RESULTS

Elevated LBP was discovered as a candidate DVT biomarker in women with less than 3 years between blood sampling and DVT. In the validation study, the odds ratio (OR) for DVT was 2.03 (95% confidence intervals [CI]: 1.53-2.74) per standard deviation (SD) increase in LBP for women with less than 3 years between blood sampling and DVT. Adjustment for age, body mass index, and C-reactive protein attenuated the OR to 1.79 (95% CI: 1.25-2.62) per SD. In the validation study, we observed an OR for VTE of 0.47 (95% CI: 0.28-0.77) for men in the 25^th to 50^th percentiles when compared to the lowest quartile.

CONCLUSIONS

We discovered and validated increased LBP as a predictive biomarker for DVT in women. We found an increased VTE risk for men in the lowest quartile of LBP.

Pulmonary embolism and deep vein thrombosis—comorbidities and temporary provoking factors in a register‐based study of 1.48 million people

Background

Knowledge on differences in patients who present with deep vein thrombosis (DVT) and those with pulmonary embolism (PE) is incomplete.

Objective

To determine comorbidities and temporary provoking factors in patients with a first‐time PE or DVT.

Methods

This was a nationwide Swedish registry‐based, retrospective, case‐control study including 298 172 patients with first‐time venous thromboembolism (VTE) and 1 185 079 controls matched for age, sex, and county of residence, free of VTE at the time of matching.

Results

Patients with PE were older than those with DVT (mean age, 69 vs 66 years) and included slightly more women (PE, 53.4% vs DVT, 52.1%). After multivariable adjustment for comorbidities (within 7 years) and temporary provoking factors (within 3 months), heart failure (PE: adjusted odds ratio [aOR], 2.64 [99% confidence interval [CI], 2.55‐2.73]; DVT: aOR, 1.66 [99% CI, 1.60‐1.72]), ischemic heart disease (PE: aOR, 1.51 [99% CI, 1.47‐1.56]; DVT: aOR, 1.01 [99% CI, 0.98‐1.04]), and chronic obstructive pulmonary disease (PE: aOR, 2.51 [99% CI, 2.40‐2.63]; DVT, 1.54 [99% CI, 1.47‐1.62]) were among diseases that showed higher odds ratios in patients with PE than in those with DVT, compared with controls. Comorbidities registered within 6 months were associated with higher aORs than those within 7 years. The highest population attributable risks for PE were for cancer (13.0%) and heart failure (11.7%).

Conclusion

Cardiopulmonary diseases, particularly with recent onset, imply a higher risk for PE, whereas orthopedic surgery and lower‐extremity fractures carry a higher risk of DVT.

Risk Factors for Major Adverse Cardiovascular Events and Major Adverse Limb Events after Venous Thromboembolism: A Large Prospective Cohort Study

BACKGROUND

 There is an increased risk of arterial events including major adverse cardiovascular events (MACE) and major adverse limb events (MALE) after venous thromboembolism (VTE). However, their risk factors remain little explored.

METHODS

 We aimed to determine the risk factors for MACE (acute coronary syndrome/stroke/cardiovascular death) and MALE (limb ischemia/critical limb ischemia/non-traumatic amputation/any limb revascularization) after VTE. Competing risk models (Fine-Gray) were used in a multicenter prospective cohort of 4,940 patients (mean age: 64.6 years and median follow-up: 64 months).

RESULTS

 MACE occurred in 17.3% of participants (2.35% per patient-years) and MALE in 1.7% (0.27% per patient-years). In multivariable analysis, the identified risk factors for MACE were the age of 50 to 65 years (vs. <50 years, hazard ratio [HR]: 2.00, 95% confidence interval [CI]: 1.38-2.91), age >65 years (vs. <50 years, HR 4.85, 95% CI: 3.35-7.02), pulmonary embolism + deep vein thrombosis (DVT) (vs. isolated-DVT, HR: 1.25, 95% CI: 1.02-1.55), unprovoked-VTE (vs. transient risk factor associated-VTE, HR: 1.29, 95% CI: 1.04-1.59), current tobacco use (vs. never, HR: 1.45, 95% CI: 1.07-1.98), hypertension (HR: 1.61, 95% CI: 1.30-1.98), past history of symptomatic atherosclerosis (HR: 1.52, 95% CI: 1.17-1.98), heart failure (HR: 1.71, 95% CI: 1.21-2.42), atrial fibrillation (HR: 1.55, 95% CI: 1.15-2.08), and vena cava filter insertion (HR: 1.46, 95% CI: 1.03-2.08). The identified risk factors for MALE were the age of 50-65 years (vs. <50 years, HR: 3.49, 95% CI: 1.26-9.65) and atrial fibrillation (HR: 2.37, 95% CI: 1.15-4.89).

CONCLUSIONS

 Risk factors for MACE and MALE after VTE included some traditional cardiovascular risk factors, patient's comorbidities, and some characteristics of VTE.

Elevated plasma D-dimer levels are associated with risk of future incident venous thromboembolism

BACKGROUND

D-dimer, a global biomarker for activation of the coagulation and fibrinolysis systems, is useful in assessing individual risk of venous thromboembolism (VTE) recurrence. However, there is limited information on the association between D-dimer and risk of a first lifetime VTE event.

OBJECTIVES

To investigate the association between plasma D-dimer levels and risk of future incident VTE.

METHODS

A population-based nested case-control study, comprising 414 VTE patients and 843 randomly selected age- and sex-matched controls, was derived from the Tromsø Study (1994-2007). D-dimer was measured in plasma samples collected at cohort baseline (1994-95). Odds ratios (ORs) for VTE with 95% confidence intervals (CIs) were estimated according to quartile cut-offs of D-dimer levels determined in controls.

RESULTS

The risk of VTE increased across quartiles of D-dimer levels (P_trend = 0.014) in the age- and sex-adjusted model. Participants with plasma D-dimer levels in the highest quartile (≥152 ng/mL) had an OR for VTE of 1.65 (95% CI 1.14-2.40) compared with those in the lowest quartile (<94 ng/mL). The ORs were marginally attenuated after additional adjustment for body mass index (BMI) (OR 1.51, 95% CI 1.04-2.20) and C-reactive protein (CRP) (OR 1.34, 95% CI 0.90-1.98). Similar results were obtained for VTE subgroups, i.e. deep vein thrombosis, pulmonary embolism, and provoked/unprovoked events.

CONCLUSION

Our results indicate that elevated plasma D-dimer levels are associated with increased risk of incident VTE. However, the attenuation of risk estimates upon additional adjustment for BMI and CRP suggests that D-dimer partly reflects underlying conditions associated with obesity and an inflammatory state.

Incidence and Risk Factors for Postoperative Venous Thromboembolic Events in Patients Undergoing Cervical Spine Surgery

STUDY DESIGN

This was a retrospective database study.

OBJECTIVE

The objective of this study was to investigate preoperative risk factors and incidence of venous thromboembolic events (VTEs) after cervical spine surgery.

SUMMARY OF BACKGROUND DATA

VTEs are preventable complications that may occur after spinal procedures. Globally, VTEs account for a major cause of morbidity and mortality. Preoperative risks factors associated with increased VTE incidence after cervical spine surgery have not been well-characterized.

MATERIALS AND METHODS

Patients undergoing anterior cervical discectomy and fusion (ACDF); posterior cervical fusion (PCF); discectomy; and decompression from 2007 to 2017 were identified using the PearlDiver Database. International Classification of Diseases (ICD) Ninth and 10th Revision codes were used to identify VTEs at 1 week, 1 month, and 3 months postoperative as well as preoperative risk factors.

RESULTS

Risk factors with the highest incidence of VTE at 3 months were primary coagulation disorder [ACDF=7.82%, odds ratio (OR)=3.96; decompression=11.24%, OR=3.03], central venous line (ACDF=5.68%, OR=2.11; PCF=12.58%, OR=2.27; decompression=10.17%, OR=2.80) and extremity paralysis (ACDF=6.59%, OR=2.73; PCF=18.80%, OR=2.99; decompression=11.86, OR=3.74). VTE incidence at 3 months for populations with these risks was significant for all surgery types (P<0.001) with the exception of patients with primary coagulation disorder who underwent PCF. Tobacco use had the lowest VTE incidence for all surgery types.

CONCLUSIONS

The total cumulative incidence of VTEs at 3-month follow-up was 3.10%, with the highest incidence of VTEs occurring within the first postoperative week (0.65% at 1 wk, 0.61% at 1 mo, 0.53% at 3 mo for ACDF; 2.56% at 1 wk, 1.93% at 1 mo, 1.45% at 3 mo for PCF; 1.37% at 1 wk, 0.93% at 1 mo, 0.91% at 3 mo for decompression). Several preoperative risk factors were found to be significant predictors for postoperative VTEs and can be used to suggest those at increased risk as well as decrease the incidence of preventable VTEs after cervical spine surgery.

LEVEL OF EVIDENCE

Level III.

Plasma Levels of Leptin and Risk of Future Incident Venous Thromboembolism

BACKGROUND

 Circulating levels of leptin, an adipocyte-derived hormone, are frequently elevated in obesity. Leptin has been reported to upregulate prothrombotic hemostatic factors in vitro and could potentially mediate venous thromboembolism (VTE) risk in obesity. However, whether leptin is associated with VTE remains uncertain.

OBJECTIVE

 This article investigates the association between plasma leptin and risk of incident VTE, and the potential of leptin to mediate VTE risk in obesity.

METHODS

 A population-based nested case-control study with 416 VTE cases and 848 age- and sex-matched controls was derived from the Tromsø Study. Logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) for VTE across leptin quartiles. Analyses were performed separately in men and women using sex-specific quartile cut-offs determined in controls.

RESULTS

 In the age-adjusted model, the VTE risk increased across leptin quartiles, particularly in men. Compared with the lowest quartile, the ORs for VTE in the highest quartile were 1.70 (95% CI 1.04-2.79) in men and 1.36 (95% CI 0.85-2.17) in women. However, with additional adjustment for body mass index (BMI), risk estimates were markedly attenuated in men (OR 1.03, 95% CI 0.55-1.93) and women (OR 0.82, 95% CI 0.45-1.48). The ORs for VTE were increased in obese men and women (BMI ≥ 30 kg/m²) and were only marginally affected after adjustment for leptin.

CONCLUSION

 Our results indicate that the apparent association between plasma leptin levels and VTE risk is confounded by BMI and that leptin is not a relevant mediator for VTE risk in obesity.

Risk Factors of Arterial Events in Patients with Venous Thromboembolism: A Systematic Review and Meta-Analysis

BACKGROUND

 If recent studies suggested that arterial ischemic events in patients with venous thromboembolism (VTE) are more frequent than in the general population without VTE, whether patients with VTE have different risk factors of arterial events than classic known cardiovascular risk factors remain undefined. Through this systematic review and meta-analysis, we aimed to identify risk factors of arterial ischemic events in patients with VTE.

METHODS

 We searched PubMed, EMBASE, and Cochrane databases to identify cohort studies published between January 1, 2000, and December 31, 2020, reporting risk factors of arterials ischemic events in patients with VTE. Random-effect models meta-analysis served to get the pooled hazard ratio (HR) and 95% confidence interval (CI) of each risk factor identified.

RESULTS

 We screened 1,467 records of which 18 were finally included in systematic review and 10 in meta-analyses. Adjusted HR for 9 factors were included in meta-analysis. Male gender (HR: 1.38; 95% CI: 1.28-1.49), diabetes (HR: 1.65; 95% CI: 1.28-2.12), hypertension (HR: 1.38; 95% CI: 1.04-1.84), previous atherothrombotic event (HR: 3.22; 95% CI: 1.12-9.23), chronic kidney disease (HR: 1.41; 95% CI: 1.05-1.88), cancer (HR: 1.72; 95% CI: 1.41-2.09), and unprovoked VTE (HR: 1.88; 95% CI: 1.37-2.57) were the identified risk factors of arterial events in VTE population after meta-analysis.

CONCLUSION

 Risk factors of arterial events in patients with VTE include usual cardiovascular risk factors and other risk factors that are related to VTE such as cancer and unprovoked VTE.

Metabolic Syndrome Increases Risk of Venous Thromboembolism Recurrence after Acute Pulmonary Embolism

Rationale: Metabolic syndrome (MetS), the clinical clustering of hypertension, dyslipidemia, insulin resistance, and abdominal obesity, has been associated with a prothrombotic and hypofibrinolytic state, although data linking MetS with venous thromboembolism (VTE) remain limited.Objectives: The aim of this study was to measure the prevalence of MetS in patients with pulmonary embolism (PE) across a large population and to examine its impact on VTE recurrence.Methods: This was a retrospective, population-based analysis using deidentified information from a large statewide database, the Indiana Network for Patient Care. All patients with an International Classification of Diseases-defined diagnosis of PE from 2004 to 2017 were included. We measured the frequency with which patients with PE carried a comorbid diagnosis of each MetS component. Multiple logistic regression analysis was performed with VTE recurrence as the dependent variable to test the independent effect of MetS diagnosis, with a statistical model using a directed acyclic graph to account for potential confounders and mediators. Kaplan-Meier curves were constructed to compare rates of VTE recurrence over time based on the presence or absence of MetS and its individual components.Results: A total of 72,936 patients were included in this analysis. The most common MetS component was hypertension with a prevalence of 59%, followed by hyperlipidemia (41%), diabetes mellitus (24%), and obesity (22%). Of these patients, 69% had at least one comorbid component of MetS. The overall incidence of VTE recurrence was 17%, increasing stepwise with each additional MetS component and ranging from 6% in patients with zero components to 37% in those with all four. Logistic regression analysis yielded an adjusted odds ratio of 3.03 (95% CI, 2.90-3.16) for the effect of composite diagnosis requiring at least three of the four components of MetS diagnosis on VTE recurrence.Conclusions: The presence of comorbid MetS in patients with PE is associated with significantly higher rates of VTE recurrence, supporting the importance of recognizing these risk factors and initiating appropriate therapies to reduce recurrence risk.

Plasma levels of growth differentiation factor 15 are associated with future risk of venous thromboembolism

Growth differentiation factor 15 (GDF-15), a marker of inflammation and oxidative stress, has emerged as a biomarker for arterial cardiovascular disease. However, the association between GDF-15 and venous thromboembolism (VTE) remains uncertain. We therefore investigated the association between plasma GDF-15 levels and future risk of incident VTE and explored the potential of a causal association using Mendelian randomization (MR). We conducted a population-based nested case-control study comprising 416 VTE patients and 848 age- and sex-matched controls derived from the Tromsø Study. Logistic regression was used to calculate odds ratios (ORs) for VTE across GDF-15 quartiles. For the MR, we used data from the International Network on Venous Thrombosis (INVENT) consortium to examine whether single nucleotide polymorphisms (SNPs) associated with GDF-15 levels with genome-wide significance were related to VTE. We found that the ORs for VTE increased across GDF-15 quartiles (Ptrend = .002). Participants with GDF-15 values in the highest quartile (≥358 pg/mL) had an OR for VTE of 2.05 (95% confidence interval, 1.37-3.08) compared with those with GDF-15 in the lowest quartile (<200 pg/mL) in the age- and sex-adjusted model. ORs remained essentially the same after further adjustment for body mass index, smoking, hormone therapy, physical activity, and C-reactive protein. Similar results were obtained for provoked/unprovoked events, deep vein thrombosis, and pulmonary embolism. GDF-15 levels, as predicted by the SNPs, were not associated with VTE in MR. Our results indicate that high GDF-15 levels are associated with increased risk of VTE, but MR suggests that this association is not causal.

Venous thromboembolism in patients hospitalized for knee joint replacement surgery

Patients undergoing knee joint replacement (KJR) are at high risk of postoperative venous thromboembolism (VTE), but data on the time trends of VTE rate in this population are sparse. In this analysis of the German nationwide inpatient sample, we included all hospitalizations for elective primary KJR in Germany 2005-2016. Overall, 1,804,496 hospitalized patients with elective primary KJR (65.1% women, 70.0 years [IQR 63.0-76.0]) were included in the analysis. During hospitalization, VTE was documented in 23,297 (1.3%) patients. Total numbers of primary KJR increased from 129,832 in 2005 to 167,881 in 2016 (β-(slope)-estimate 1,978 [95% CI 1,951 to 2,004], P < 0.001). In-hospital VTE decreased from 2,429 (1.9% of all hospitalizations for KJR) to 1,548 (0.9%) cases (β-estimate - 0.77 [95% CI - 0.81 to - 0.72], P < 0.001), and in-hospital death rate from 0.14% (184 deaths) to 0.09% (146 deaths) (β-estimate - 0.44 deaths per year [95% CI - 0.59 to - 0.30], P < 0.001). Infections during hospitalization were associated with a higher VTE risk. VTE events were independently associated with in-hospital death (OR 20.86 [95% CI 18.78-23.15], P < 0.001). Annual number of KJR performed in Germany increased by almost 30% between 2005 and 2016. In parallel, in-hospital VTE rates decreased from 1.9 to 0.9%. Perioperative infections were associated with higher risk for VTE. Patients who developed VTE had a 21-fold increased risk of in-hospital death.

Acute pulmonary embolism in COVID-19 disease: Preliminary report on seven patients

There is some evidence that Covid 19 pneumonia is associated with prothrombotic status and increased risk of venous thromboembolic events (deep venous thrombosis and pulmonary embolism). Over a two-week period we admitted in our Unit 25 patients with Covid-19 pneumonia, of these pulmonary embolism was diagnosed using computed tomography angiography in 7. We report on clinical and biochemical features of these patients. They were all males, with a mean age of 70.3 years (range 58-84); traditional risk factors for venous thromboembolism were identified in the majority of patients with pulmonary embolism, however not differently from those without pulmonary embolism. Clinical presentation of pulmonary embolism patients was usually characterized by persistence or worsening of respiratory symptoms, with increasing oxygen requirement. D-dimer levels were several fold higher than the upper threshold of normal; in patients in whom PE was recognized during hospital stay, a rapid and relevant increase of D-dimer levels was observed. Computed tomographic findings ranged from massive acute pulmonary embolism to a segmental or sub-segmental pattern; furthermore, thrombosis of sub-segmental pulmonary arteries within lung infiltrates were occasionally seen, suggesting local mechanisms. Six out of 7 patients were treated with unfractionated or low molecular weight heparin with clinical benefit within few days; one patient needed systemic thrombolysis (death from hemorrhagic complication).

Comorbidity and risk of venous thromboembolism after hospitalization for first-time myocardial infarction: A population-based cohort study

BACKGROUND

Myocardial infarction (MI) is a risk factor for venous thromboembolism (VTE). Although comorbidities affect MI prognosis, it is unclear whether they affect VTE risk after MI.

OBJECTIVES

We examined the impact of comorbidity on VTE risk after MI.

METHODS

We used nationwide population-based registries to identify first-time hospitalizations for MI and subsequent occurrence of VTE in Denmark (1995-2013). We included a comparison cohort from the general population matched 5:1 with MI patients by sex, age, and comorbidities. We computed 30-day and 1- to 12-month cumulative risks, rates, and hazard ratios of VTE. We also assessed the interaction between MI and comorbidity, defined as excess VTE risk in patients with both MI and comorbidity, by computing interaction contrasts and attributable fractions relating to the interaction.

RESULTS

Thirty-day and 1- to 12-month VTE risks were 0.6% and 0.5% in the MI cohort (n = 160 338) and 0.03% and 0.3% in the comparison cohort (n = 792 384). The 30-day hazard ratio for VTE in the MI cohort was 23 (95% confidence interval, 20-27), which decreased during 1-year follow-up. Thirty days after MI, interactions between MI and comorbidity accounted for 16% and 39% of VTE rates in MI patients with low-to-moderate and high comorbidity, respectively. The interactions were driven primarily by hemiplegia and cancer.

CONCLUSIONS

Thirty-day VTE risk was substantially increased after MI compared with the general population. Although the absolute VTE risk was low, comorbidity substantially increased this risk, especially hemiplegia and cancer. VTE prophylaxis might be indicated in such high-risk patients but warrants further investigation.

Venous thromboembolism in patients hospitalized for hip joint replacement surgery

BACKGROUND

Venous thromboembolism (VTE) is a potentially life-threatening disease. Major transient risk factors include trauma, surgery, and immobilization. Patients undergoing hip joint replacement (HJR) are characterized by a high risk of postoperative VTE, but data on the time trends of VTE rates in this population are sparse.

METHODS

In an analysis of the German nationwide inpatient sample, we included all hospitalizations for elective primary HJR in Germany from 2005 to 2016. Time trends of the surgical procedure, overall death rates, and VTE rates were analysed, and predictors of VTE identified.

RESULTS

Overall, 1,885,839 inpatients with elective primary HJR (59.1% women, 51.4% ≥70 years) were included in the analysis. During hospitalization, VTE was documented in 11,554 (0.6%) patients. While total numbers of primary HJR increased from 145,223 in 2005 to 171,421 in 2016 (β-(slope)-estimate 1818 [95%CI 1083 to 2553], P < 0.001), in-hospital VTE decreased from 1288 (0.9%) to 843 (0.5%) cases (β-estimate -0.71 [95%CI -0.77 to -0.65], P < 0.001), and in-hospital death rate from 0.33% (476 deaths) to 0.29% (498 deaths) (β-estimate -0.11 [95%CI -0.20 to -0.02], P = 0.018). Infections during hospitalization were associated with higher VTE risk than cancer and cardiovascular events. VTE events were independently associated with an increased death risk (OR 15.19 [95%CI 14.19-16.86], P < 0.001).

CONCLUSIONS

While total numbers of HJR increased significantly in Germany between 2005 and 2016, in-hospital rates of VTE decreased from 0.9% to 0.5%. Patients with perioperative VTE had a 15-fold increase of in-hospital death. Cancer, cardiovascular disease and perioperative infections were associated with higher risk for VTE.

Myocardial infarction, prothrombotic genotypes, and venous thrombosis risk: The Tromsø Study

BACKGROUND

The risk of venous thromboembolism (VTE) is increased after a myocardial infarction (MI). Some prothrombotic genotypes associated with VTE have also been associated with risk of MI. Whether prothrombotic single-nucleotide polymorphisms (SNPs) further increase the risk of VTE in MI patients is scarcely investigated.

AIM

To study the combined effect of MI and prothrombotic SNPs on the risk of VTE.

METHODS

Cases with incident VTE (n = 641) and a randomly sampled subcohort weighted for age (n = 1761) were identified from the 4 to 6 surveys of the Tromsø Study (1994-2012). DNA was genotyped for rs8176719 (ABO), rs6025 (F5), rs1799963 (F2), rs2066865 (FGG), and rs2036914 (F11). Hazard ratios (HRs) for VTE with 95% confidence intervals (CIs) were estimated by categories of risk alleles and MI status.

RESULTS

Patients with MI had a 1.4-fold increased risk of VTE, and adjustments for the 5 SNPs, either alone or in combination, did not affect this relationship (adjusted HR, 1.52; 95% CI, 1.12-2.07). In subjects without MI, an increased risk of VTE was observed for each of the individual SNPs (≥1 vs. 0 risk alleles), and the risk increased linearly with increasing number of risk alleles in the 5-SNP score. The combination of MI and prothrombotic genotypes, either as individual SNPs or in the 5-SNP score, did not result in an excess risk of VTE.

CONCLUSION

The relationship between MI and VTE was not explained by these 5 prothrombotic genotypes. Prothrombotic genotypes did not yield an excess risk of VTE in patients with MI.

Serum amyloid A4 is a procoagulant apolipoprotein that it is elevated in venous thrombosis patients

BACKGROUND

Serum amyloid A4 (SAA4) is an apolipoprotein that is in the SAA family and it is constitutively translated. Previously, acute-phase SAA1 and SAA2 levels were associated with venous thromboembolism (VTE).

OBJECTIVE

We investigated the association of plasma SAA4 with VTE and the role of SAA4 in coagulation.

PATIENTS AND METHODS

The association of SAA4 with VTE in a case-control study of adult VTE subjects (N = 113 each group) and the effects of recombinant SAA4 on plasma blood coagulation assays and prothrombin activation initiated by factor Xa were evaluated.

RESULTS

Plasma SAA4 levels in VTE subjects were higher vs. controls (48.1 vs. 38.4 µg/mL; P < .001). Elevated plasma SAA4 level (above the 90th percentile of controls) was associated with increased VTE occurrence (odds ratio, 3.8; 95% confidence interval, 1.8-8.0). This association remained significant after the adjustment for acute-phase SAA level, suggesting that SAA4 associated with VTE is independent of acute-phase SAA. Two isoforms of SAA4, that is, glycosylated and nonglycosylated SAA4 isoforms, were each higher in VTE patients. When recombinant SAA4 was added to plasma, it shortened factor Xa-1-stage clotting times, showing that it enhances clotting in plasma. In reaction mixtures containing purified factors Xa and Va and prothrombin, recombinant SAA4 increased prothrombin activation, showing that it enhances prothrombinase activity.

CONCLUSION

Elevated plasma constitutive SAA4 levels were linked to VTE in adults, and SAA4 can enhance thrombin generation in plasma. Our data highlight a previously unknown procoagulant activity of SAA4 that appears to be related to risk of venous thrombotic events.

Plasma levels of mannose-binding lectin and future risk of venous thromboembolism

BACKGROUND

Animal and observational studies have suggested a pathophysiological role for complement in venous thromboembolism (VTE), but the initiating mechanisms are unknown. Mannose-binding lectin (MBL) bound to altered host cells leads to activation of the lectin complement pathway, and both high and low MBL levels have been implicated in the pathophysiology of cardiovascular disease.

OBJECTIVES

To investigate the association between plasma MBL levels and future risk of incident VTE.

METHODS

We conducted a nested case-control study in 417 VTE patients and 849 age-matched and sex-matched controls derived from the general population (Tromsø Study). Plasma MBL levels were measured using enzyme-linked immunosorbent assay. Logistic regression models were used to estimate odds ratio (OR) for VTE across quartiles of plasma MBL levels.

RESULTS

Subjects with plasma MBL levels in the lowest quartile (<435 ng/mL) had a reduced OR for overall VTE (OR 0.79, 95% confidence interval [CI]: 0.56-1.10) and for DVT (OR 0.70, 95% CI: 0.47-1.04) compared to those with MBL in the highest quartile (≥2423 ng/mL) after multivariable adjustments. For VTE, DVT, and pulmonary embolism (PE) the ORs decreased substantially with decreasing time between blood sampling and VTE event.

CONCLUSIONS

Our findings suggest that low plasma MBL levels are associated with reduced risk of VTE, and DVT in particular.

Impact of prothrombotic genotypes on the association between family history of myocardial infarction and venous thromboembolism

BACKGROUND

Family history of myocardial infarction (FHMI) is known to increase the risk of venous thromboembolism (VTE).

OBJECTIVES

To investigate the effect of prothrombotic genotypes on the association between FHMI and VTE in a case-cohort recruited from a general population.

METHODS

Cases with a first VTE (n = 1493) and a subcohort (n = 13 072) were sampled from the Tromsø study (1994-2012) and the Nord-Trøndelag health (HUNT) study (1995-2008). The DNA samples were genotyped for rs8176719 (ABO), rs6025 (F5), rs1799963 (F2), rs2066865 (FGG), and rs2036914 (F11). Participants with missing information on risk alleles (n = 175), FHMI (n = 2769), and BMI (n = 52) were excluded. Cox regression models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CI) for VTE. To explore the role of prothrombotic genotypes for the association between FHMI and VTE, we (a) included the genotypes in the multivariable-adjusted models and (b) assessed the joint effects between FHMI and genotypes on VTE risk.

RESULTS

The FHMI was associated with a 1.3-fold increased risk of VTE (HR 1.32, 95% CI 1.16-1.50) and 1.5-fold increased risk of unprovoked VTE (HR 1.47, 95% CI 1.22-1.78). The risk of VTE by FHMI did not alter after adjustment for the five genotypes. The combination of FHMI and the different prothrombotic genotypes did not result in an excess VTE risk (i.e. no biological interaction).

CONCLUSIONS

Our findings suggest that the risk of VTE by FHMI is not explained by rs8176719 (ABO), rs6025 (F5), rs1799963 (F2), rs2066865 (FGG), and rs2036914 (F11). The combination of FHMI with prothrombotic genotypes had an additive effect on VTE risk.

Effect of prothrombotic genotypes on the risk of venous thromboembolism in patients with and without ischemic stroke. The Tromsø Study

Essentials Prothrombotic genotypes may agument the risk of venous thromboembolism (VTE) after ischemic stroke. We studied this effect in a case-cohort study using a genetic risk score. In stroke patients, a one-category increase in the genetic risk score was associated with a 50% higher relative risk of VTE. The risk of VTE in stroke patients increased with an increasing number of risk alleles. SUMMARY: Background Patients with ischemic stroke have a transiently increased risk of subsequent venous thromboembolism (VTE). Prothrombotic genotypes may augment VTE risk under conditions of high thrombosis risk related to stroke. Aims To investigate the effect of prothrombotic genotypes in patients with ischemic stroke on the risk of VTE in a population-based case-cohort study. Methods Cases with incident VTE (n = 664) and a randomly selected age-weighted subcohort (n = 1817) were sampled from three surveys of the Tromsø Study (1994-2008). Participants were genotyped for ABO (rs8176719), F5 (rs6025), F2 (rs1799963), FGG (rs2066865) and F11 (rs2036914) single-nucleotide polymorphisms (SNPs). Cox regression models were used to calculate hazard ratios (HRs) for incident VTE according to individual SNPs and categories of risk alleles (5-SNP score; 0-1, 2, 3-4 and ≥ 5) in participants with and without ischemic stroke. Results There were 192 patients with incident stroke, of whom 43 developed VTE during a median of 15.2 years of follow-up. The risk alleles of individual SNPs augmented the elevated VTE risk brought about by ischemic stroke. In stroke patients, a one-category increase in the genetic risk score was associated with a 50% higher relative risk of overall VTE (HR 1.5, 95% confidence interval [CI] 1.3-1.8) and an 80% higher relative risk of provoked VTE (HR 1.8, 95% CI 1.5-2.1). Stroke patients with ≥ 5 risk alleles had a 12-fold (HR 11.7, 95% CI 4.1-33.3) higher relative risk of VTE than stroke-free participants with 0-1 risk alleles. Conclusions Prothrombotic genotypes increased the risk of VTE in stroke patients, and the risk increased with an increasing number of risk alleles.

Searching for a Common Thrombo-Inflammatory Basis in Patients With Deep Vein Thrombosis or Peripheral Artery Disease

Background: Inflammation and hypercoagulability play a pivotal role in venous thromboembolism and atherothrombosis. Since venous thrombosis increases the risk of atherothrombotic events and vice versa, common mechanisms may be involved.

Objectives: To elucidate the role of neutrophils and coagulation in the occurrence of atherothrombotic events in patients with a history of deep vein thrombosis (DVT or peripheral artery disease (PAD).

Materials and Methods: We studied 115 patients from two cohorts (75 DVT, 40 PAD). From those with PAD, 20 patients had progressive disease; from those with DVT, 25 patients had a recurrent DVT and 25 suffered from post thrombotic syndrome (PTS); patients were age and sex matched to DVT and PAD patients without events. Markers of neutrophil recruitment (p-selectin) and activation [nucleosomes, human neutrophil elastase- α1anti-trypsin (HNE-AT)], an anti-inflammatory marker (Lipoxin A4) and a clotting activity marker (d-dimer), were measured with ELISA. Coagulation potential was analyzed by thrombin generation (CAT method).

Results: Higher nucleosome levels were found in DVT patients [11.3 U/mL (7.4–17.7)] compared to PAD patients [7.1 U/mL (5.1–13.8)], lower HNE-AT levels were found in DVT patients [33.4 ng/mL (23.5–40.5)] in comparison to PAD patients [158 ng/mL (88.1–283)]. No difference in nucleosome levels was found between DVT patients with cardiovascular (CV) events [12.6 U/mL (8.2–16.1)], and PAD patients with CV events [6.9 U/mL (4.9–11.2)]. Lipoxin A4 levels appeared to be significantly lower in DVT [2.4 ng/mL (1.7–4.8)] vs. PAD [35.6 ng/mL (16.6–80.1)], with similar results in DVT patients with CV events vs. PAD patients with CV events. Thrombin generation showed higher ETP [160.4% (141.1–215.4)], and peak height [292.1% (177.9–330)] values in DVT patients. D-dimer levels were significantly lower in the DVT cohort [330 ng/mL (220–550)] compared to the PAD cohort [550 ng/mL (369–959)].

Conclusion: In DVT patients, neutrophil activity does not appear to be an important driver of CV events. Although neutrophil activity is more pronounced in PAD, its effect is partly dampened by Lipoxin A4. Moreover, no associations were found between NET products and coagulation activity, suggesting that neutrophil activation does not play a pivotal role in the risk of thrombosis in either DVT or PAD.

Venous thromboembolism prophylaxis using the Caprini score

Venous thromboembolism (VTE) including pulmonary embolism (PE) and deep vein thrombosis (DVT) is one of the leading causes of preventable cardiovascular disease in the United States (US) and is the number one preventable cause of death following a surgical procedure. Post-operative VTE is associated with multiple short and long-term complications. We will focus on reviewing the many faces of VTE in detail as they represent common challenging scenarios in clinical practice.

Repeated assessments of physical activity and risk of incident venous thromboembolism

Essentials It is debated whether physical activity influences the risk of venous thromboembolism. The association was explored accounting for fluctuations in physical activity over time. Overall and in the elderly, physical activity was associated with 23% and 30% lower risk. A moderate proportion of the association (14-36%) was mediated via body mass index. SUMMARY: Background Whether physical activity influences the risk of incident venous thromboembolism (VTE) remains controversial, potentially because of methodological challenges, such as regression dilution bias. Objectives To investigate whether physical activity was associated with VTE risk, and explore the role of body mass index (BMI) as a mediator in a population-based cohort with repeated assessments of physical activity. Methods Participants (n = 30 002) attending one or more surveys of the Tromsø Study 4-6 (1994-1995, 2001-2002, and 2007-2008) were included and categorized on the basis of weekly physical activity. Incident VTE was registered until 31 December 2016. Hazard ratios (HRs) were calculated by the use of time-varying Cox regression models. The Aalen additive hazard model was used to quantify the total, direct and indirect effects of physical activity. Results There were 531 incident VTEs during follow-up. Physical activity (≥ 1 per week) was associated with a lower risk of VTE (HR 0.77, 95% confidence interval [CI] 0.64-0.92) than being inactive. The effect was most pronounced for those aged ≥ 65 years (HR 0.70, 95% CI 0.55-0.88) and for provoked events (HR 0.66, 95% CI 0.50-0.89). The differences in absolute risk between active and inactive individuals were - 0.42 (95% CI - 0.73 to - 0.14) and - 1.59 (95% CI - 2.74 to - 0.52) events annually per 1000 individuals in the total and elderly populations, respectively. A moderate proportion of the association (14-36%) was mediated via BMI. Conclusion Our findings suggest that regular physical activity is associated with a lower risk of VTE, particularly in the elderly. The association occurred at a low weekly amount of physical activity, and was only partly mediated by BMI.

Repeated measurements of carotid atherosclerosis and future risk of venous thromboembolism: the Tromsø Study

Essentials The relationship between atherosclerosis and venous thromboembolism (VTE) is controversial. In total, 10 426 participants recruited from the general population were included. Carotid intima media thickness and total plaque area was not associated with VTE. There was no association between plaque initiation or plaque progression and subsequent VTE.

SUMMARY

Background Whether a relationship between atherosclerosis and subsequent venous thromboembolism (VTE) exists is controversial. Objective To investigate the association between carotid atherosclerosis and VTE by using repeated measurements of intima media thickness (IMT) and total plaque area (TPA) in participants recruited from the general population. Methods Participants were recruited from the fourth (1994-1995), fifth (2001-2002) and sixth (2007-2008) surveys of the Tromsø Study. In total, 10 426 participants attended, for whom measurements of carotid IMT and TPA and potential confounders were updated at each available survey. Time-varying Cox regression models were used to calculate hazard ratios (HRs) of VTE across various levels of IMT and TPA adjusted for age, sex, and body mass index. Results There were 368 incident VTE events during a median follow-up of 10.8 years. Participants with increasing IMT were, on average, older and had a less favorable cardiovascular risk profile. There was no association between tertiles of increasing TPA and the risk of VTE in the time-varying model, and increasing IMT was not associated with an increased risk of VTE (HR 0.96, 95% confidence interval [CI] 0.86-1.07). Neither plaque formation nor plaque progression was associated with the risk of VTE (respectively: HR 1.00, 95% CI 0.98-1.02; and HR 0.96, 95% CI 0.84-1.11). Conclusion Carotid IMT and TPA were not associated with an increased risk of VTE in time-varying analyses. Furthermore, there was no association between plaque initiation or plaque progression and subsequent VTE.

Associations between serum levels of calcium, parathyroid hormone and future risk of venous thromboembolism: the Tromsø study

OBJECTIVE

The relationship between serum levels of calcium, parathyroid hormone (PTH) and risk of venous thromboembolism (VTE) has not been addressed in population-based cohorts. We investigated the associations between serum levels of calcium and PTH, with future risk of VTE in a general adult population.

DESIGN

Population-based cohort.

METHODS

A total of 27 712 subjects (25-87 years) who participated in Tromsø 4 (1994-1995) and Tromsø 5 (2001-2002) surveys were included in the study, and total calcium and PTH were measured in 27 685 and 8547 subjects respectively. Incident VTE was recorded through December 31, 2012. Cox-regression models with calcium and PTH as time-varying exposures were used to calculate hazard ratios (HR) of VTE by quartiles of calcium and PTH. Quartiles of calcium and PTH were also combined to assess the effect of discordants of both PTH and calcium (e.g. highest and lowest quartiles of both calcium and PTH) on VTE risk using the middle two quartiles as reference.

RESULTS

There were 712 VTEs during 15.0 years of median follow-up. Serum levels of calcium and PTH were not associated with risk of VTE. However, subjects with discordant high serum levels of both calcium and PTH (calcium ≥2.45 mmol/L and PTH ≥4.0 pmol/L) had increased risk of VTE compared to those in subjects with normal calcium and PTH (multivariable HR: 1.78, 95% CI: 1.12-2.84).

CONCLUSIONS

Serum levels of calcium and PTH separately were not associated with future risk of VTE, but subjects with high levels of both calcium and PTH had increased risk of VTE compared to those in subjects with normal levels.

Thrombosis and platelets: an update

Haemostasis and thrombosis are complex, multifactorial processes. There is an evolving understanding of the mechanisms influencing vascular occlusion and the role of inflammation and immunity. Despite major advances in elucidating the mechanistic pathways mediating platelet function and thrombosis, challenges in the treatment of vascular occlusive diseases persist. Pharmacological advances have greatly affected thrombotic outcomes, but this has led to the unwanted side effect of bleeding. Detailed assessment of the impact of non-thrombotic diseases on haemostasis and thrombosis is necessary to better evaluate thrombotic risk and establish optimal treatment. This review will focus on recent advances in understanding the contribution of evolving risk factors to thrombosis.

PDGFB, a new candidate plasma biomarker for venous thromboembolism: results from the VEREMA affinity proteomics study

High-throughput affinity plasma proteomic profiling can identify candidate plasma biomarkers for VTE. Elevated plasma PDGFB levels are identified as associated with VTE in 2 independent case control studies.

Atherosclerotic Risk Factors and Risk of Myocardial Infarction and Venous Thromboembolism; Time-Fixed versus Time-Varying Analyses. The Tromsø Study

Background

Single measurements of modifiable risk factors may underestimate associations with outcomes in cohorts. We aimed to compare risk estimates of myocardial infarction (MI) and venous thromboembolism (VTE) by atherosclerotic risk factors during long follow-up using time-fixed analyses without and with correction for regression dilution and time-varying analyses.

Methods

The study included 5970 subjects enrolled in the fourth survey of the Tromsø Study (1994/95). Blood pressure, lipid levels, body mass index (BMI), diabetes and smoking status were measured at baseline, and subjects still alive at the fifth (2001/02, n = 5179) and sixth (2007/08, n = 4391) survey were re-measured. Incident events of MI (n = 714) and VTE (n = 214) were recorded until December 2010. Time-fixed and time-varying Cox regression models were used to estimate hazard ratios (HR) for MI and VTE adjusted for age and sex.

Results

Variations in BMI, blood pressure and lipid levels were small, and did not alter the risk estimates when time-varying analyses were compared to time-fixed analyses. For MI, variables that changed considerably over time yielded the greatest changes in risk estimates (HR for smoking changed from 1.80 (95% CI 1.55–2.10) to 2.08 (95% CI 1.78–2.42)). For VTE, only BMI was associated with increased risk in both time-fixed and time-varying analysis, but the risk estimates weakened in the time-varying analysis. Correction of time-fixed HRs with Rosner´s method tended to overestimate risk estimates compared to time-varying analysis.

Comment

For MI and VTE, risk estimates based on baseline and repeated measures corresponded well, whereas correction for regression dilution tended to overestimate risks.