The fatty liver index and risk of incident venous thromboembolism: the Tromsø Study.

Background: For the relationship between obesity and venous thromboembolism (VTE), nonalcoholic fatty liver disease (recently termed metabolic dysfunction-associated steatotic liver disease) is of interest given the hepatic role in hemostasis. Objectives: We aimed to assess the association between the fatty liver index (FLI), as a proxy for nonalcoholic fatty liver disease, and VTE risk in a population-based cohort. Methods: Data from the Tromsø 4 (1994-1995) and 6 (2007-2008) surveys were used to calculate the FLI in 9870 participants. All VTEs were recorded up to December 31, 2020. We used Cox regression to estimate hazard ratios for VTE with 95% CIs by FLI groups defined according to clinical cut-offs (<30, 30-59, and ≥60). Because waist circumference and body mass index (BMI) are main determinants for FLI calculation, we assessed the potential contribution of FLI to VTE risk beyond these body fat measures. Results: During a median follow-up of 13.1 years, 507 incident VTEs occurred. Compared with the reference group (FLI < 30), the hazard ratios for VTE were 1.5 (95% CI, 1.1-1.9) and 1.8 (95% CI, 1.4-2.3) for the FLI 30-59 and ≥60 groups, respectively, in models adjusted for age, sex, alcohol intake, educational level, and physical activity. The association of FLI with VTE was no longer observed, with risk estimates close to unity, when participants were stratified by clinical categories of waist circumference and BMI. Conclusion: Higher values of the FLI were associated with a higher VTE risk. This association was explained by waist circumference and BMI, which reflect excessive body fat deposition and are determinants of the FLI.

Joint effect of ischemic stroke and obesity on the risk of venous thromboembolism: the Tromsø Study.

Background: Patients with ischemic stroke have increased risk of venous thromboembolism (VTE). Obesity is prevalent in stroke patients and a well-established risk factor for VTE. Whether obesity further increases the VTE risk in patients with stroke remains unclear. Objectives: We investigated the joint effect of ischemic stroke and obesity on the risk of incident VTE in a population-based cohort. Methods: Participants (n = 29,920) were recruited from the fourth to sixth surveys of the Tromsø Study (1994-1995, 2001, and 2007-2008) and followed through 2014. Incident events of ischemic stroke and VTE during follow-up were recorded. Hazard ratios (HRs) of VTE with 95% CIs were estimated according to combined categories of ischemic stroke and obesity (body mass index ≥ 30 kg/m2), with exposure to neither risk factors as reference. Results: During a median follow-up of 19.6 years, 1388 participants experienced ischemic stroke and 807 participants developed VTE. Among those with stroke, 51 developed VTE, yielding an incidence rate of VTE after stroke of 7.2 per 1000 person-years (95% CI, 5.5-9.5). In subjects without stroke, obesity was associated with a 1.8-fold higher VTE risk (HR, 1.76; 95% CI, 1.47-2.11). In nonobese subjects, stroke was associated with a 1.8-fold higher VTE risk (HR, 1.77; 95% CI, 1.27-2.46). Obese subjects with stroke had a 2-fold increased VTE risk (HR, 2.44; 95% CI, 1.37-4.36). Conclusion: The combination of obesity and ischemic stroke did not yield an excess risk of VTE. Our findings suggest that obese subjects with ischemic stroke do not have a more than additive risk of VTE.

Proportion of venous thromboembolism attributed to recognized prothrombotic genotypes in men and women.

Background: Data on the proportion of venous thromboembolism (VTE) risk attributed to prothrombotic genotypes in men and women are limited. Objectives: We aimed to estimate the population attributable fraction (PAF) of VTE for recognized, common prothrombotic genotypes in men and women using a population-based case cohort. Methods: Cases with incident VTE (n = 1493) and a randomly sampled subcohort (n = 13,069) were derived from the Tromsø study (1994-2012) and the Trøndelag Health Study (1995-2008) cohorts. DNA samples were genotyped for 17 single-nucleotide polymorphisms (SNPs) previously associated with VTE. PAFs with 95% bias-corrected CIs (based on 10,000 bootstrap samples) were estimated for SNPs significantly associated with VTE, and a 6-SNP cumulative model was constructed for both sexes. Results: In women, the individual PAFs for SNPs included in the cumulative model were 16.9% for ABO (rs8176719), 17.6% for F11 (rs2036914), 15.1% for F11 (rs2289252), 8.7% for FVL (rs6025), 6.0% for FGG (rs2066865), and 0.2% for F2 (rs1799963). The cumulative PAF for this 6-SNP model was 37.8%. In men, the individual PAFs for SNPs included in the cumulative model were 21.3% for ABO, 12.2% for F11 (rs2036914), 10.4% for F11 (rs2289252), 7.5% for FVL, 7.8% for FGG, and 1.1% for F2. This resulted in a cumulative PAF in men of 51.9%. Conclusion: Our findings in a Norwegian population suggest that 52% and 38% of the VTEs can be attributed to known prothrombotic genotypes in men and women, respectively.

Real-world Data on Treatment Patterns and Bleeding in Cancer-associated Thrombosis: Data from the TROLL Registry.

Background International guidelines are increasingly recommending direct oral anticoagulants (DOACs) as the first-line treatment for cancer-associated thrombosis (CAT). However, data regarding treatment patterns and adherence to guidelines in patients with CAT are scarce. Objectives This study aimed to explore anticoagulant treatment patterns in patients with CAT and to calculate the incidence rates of bleeding events. Methods Patients ≥18 years with active cancer and a first-time venous thromboembolism between 2005 and 2020 were identified through the Venous T hrombosis R egistry in Østf OL d Hospita L . Outcome measures were patterns of anticoagulant treatment during the study period and bleeding events. We calculated overall incidence rates per 100 person-years and 6- and 12-month cumulative incidence of major and clinically relevant nonmajor bleeding (CRNMB) during anticoagulant treatment. Results Median age of 842 CAT patients at the time of thrombosis was 69 years (interquartile range 61-77), and 443 (52.6%) were men. In total, 526 patients (62.5%) had pulmonary embolism and 255 (30.3%) had deep vein thrombosis. Low molecular weight heparin (LMWH) was prescribed to 713 (85.8%) patients, whereas 64 (7.7%) received DOACs and 54 (6.5%) received vitamin K antagonists as the initial anticoagulant treatment. Prescription of DOACs as initial treatment increased from 3.0% in 2013/2014 to 18.0% in 2019/2020. The incidence rate of major bleeding was 6.9 (95% confidence interval [CI] 5.2-9.2) and 10.1 (95% CI 8.0-12.9) in CRNMB. Conclusion Most patients were treated with LMWH. However, a gradual shift in treatment toward DOACs was observed. Overall, bleeding complications were rare and comparable to those reported in randomized trials.

High microRNA-145 plasma levels are associated with decreased risk of future incident venous thromboembolism: the HUNT study.

ABSTRACT: MicroRNA-145 (miR-145) has been reported to downregulate the expression of tissue factor and factor XI in vitro and decrease venous thrombus formation in animal models. However, the association between miR-145 and risk of future venous thromboembolism (VTE) in the general population remains unknown. We investigated the association between plasma levels of miR-145 and risk of future VTE in a case-cohort study. Incident VTE cases (n = 510) and a subcohort (n = 1890) were derived from the third survey of the Trøndelag Health Study (HUNT3), a population-based cohort. The expression levels of miR-145 were measured in plasma samples obtained at baseline. The study population was divided into quartiles based on miR-145 levels in participants in the subcohort, and weighted Cox regression was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs). Plasma levels of miR-145 were inversely associated with VTE risk. Participants with miR-145 levels in the highest quartile had a 49% lower risk of VTE (HR, 0.51; 95% CI, 0.38-0.68) than those with miR-145 in the lowest quartile in age- and sex-adjusted analysis, and the inverse association was most pronounced for unprovoked VTE (HR, 0.39; 95% CI, 0.25-0.61). Risk estimates remained virtually the same after further adjustment for body mass index, and cancer and arterial cardiovascular disease at baseline. In conclusion, elevated expression levels of miR-145 in plasma were associated with decreased risk of future incident VTE. The protective role of miR-145 against VTE is consistent with previous experimental data and suggests that miR-145 has the potential to be a target for VTE prevention.

Incidence of venous thromboembolism, recurrence, and bleeding after isolated superficial vein thrombosis: findings from the Venous Thrombosis Registry in Østfold Hospital.

BACKGROUND: There are limited data on the long-term risk of venous thromboembolism (VTE) after high-risk isolated superficial vein thrombosis (iSVT) treated with anticoagulants. OBJECTIVES: To determine the short- and long-term risk of VTE and iSVT recurrence after cessation of anticoagulant treatment and to calculate 45-day cumulative bleeding incidence in patients with iSVT. METHODS: Between January 2014 and December 2021, 229 patients with high-risk iSVT (ie, thrombus length ≥5cm), without active cancer, with no history of VTE or iSVT, and who had received anticoagulant treatment for the iSVT were identified through the Venous Thrombosis Registry in Østfold Hospital (TROLL registry), Norway. Cumulative incidences of VTE and iSVT recurrence, as well as cumulative incidences of major and clinically relevant nonmajor bleeding events, were assessed. RESULTS: Median age was 60 years (IQR, 48-71), and 125 (55%) were women. Most patients were treated with direct oral anticoagulants (74%), and of these, 79% received a dose of rivaroxaban 10 mg daily. Low-molecular-weight heparin was given to 26% of the patients. The 1- and 5-year cumulative incidences of VTE after iSVT were 4.6% (95% CI, 2.5-8.3) and 15.9% (95% CI, 10.8-22.9), respectively. Further, the 1- and 5-year cumulative incidences of iSVT recurrence were 6.5% (95% CI, 3.9-10.7) and 15.9% (95% CI, 10.8-23.1), respectively. The overall 45-day cumulative incidence of major and clinically relevant nonmajor bleeding events was 0.4% (95% CI, 0.06-3.06) and 1.8% (95% CI, 0.7-4.6), respectively. No major bleeding events were observed in patients treated with direct oral anticoagulants. CONCLUSION: Despite anticoagulant treatment, the risk of VTE after high-risk iSVT was substantial, while bleeding complications were low.

The Risk of Incident Venous Thromboembolism Attributed to Overweight and Obesity: The Tromsø Study.

BACKGROUND: Obesity is a well-established risk factor for venous thromboembolism (VTE). However, data on the proportion of incident VTEs attributed to overweight and obesity in the general population are limited. OBJECTIVE: To investigate the population attributable fraction (PAF) of VTE due to overweight and obesity in a population-based cohort with repeated measurements of body mass index (BMI). METHODS: Participants from the fourth to seventh surveys of the Tromsø Study (enrolment: 1994-2016) were followed through 2020, and all incident VTEs were recorded. In total, 36,341 unique participants were included, and BMI measurements were updated for those attending more than one survey. BMI was categorized as <25 kg/m2, 25-30 kg/m2 (overweight), and ≥30 kg/m2 (obesity). Time-varying Cox regression models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). The PAF was estimated based on age- and sex-adjusted HRs and the prevalence of BMI categories in VTE cases. RESULTS: At baseline, the prevalence of overweight and obesity was 37.9 and 13.8%, respectively. During a median follow-up of 13.9 years, 1,051 VTEs occurred. The age- and sex-adjusted HRs of VTE were 1.40 (95% CI: 1.21-1.61) for overweight and 1.86 (95% CI: 1.58-2.20) for obesity compared with subjects with BMI <25 kg/m2. The PAF of VTE due to overweight and obesity was 24.6% (95% CI: 16.6-32.9), with 12.9% (95% CI: 6.6-19.0) being attributed to overweight and 11.7% (95% CI: 8.5-14.9) to obesity. Similar PAFs were obtained in analyses stratified by sex and VTE subtypes (provoked/unprovoked events, deep vein thrombosis, pulmonary embolism). CONCLUSION: Our findings indicate that almost 25% of all VTE events can be attributed to overweight and obesity in a general population from Norway.

Surgery As a Trigger for Incident Venous Thromboembolism: Results from a Population-Based Case-Crossover Study.

Background Surgery is a major transient risk factor for venous thromboembolism (VTE). However, the impact of major surgery as a VTE trigger has been scarcely investigated using a case-crossover design. Aim To investigate the role of major surgery as a trigger for incident VTE in a population-based case-crossover study while adjusting for other concomitant VTE triggers. Methods We conducted a case-crossover study with 531 cancer-free VTE cases derived from the Tromsø Study cohort. Triggers were registered during the 90 days before a VTE event (hazard period) and in four preceding 90-day control periods. Conditional logistic regression was used to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for VTE according to major surgery and after adjustment for other VTE triggers. Results Surgery was registered in 85 of the 531 (16.0%) hazard periods and in 38 of the 2,124 (1.8%) control periods, yielding an OR for VTE of 11.40 (95% CI: 7.42-17.51). The OR decreased to 4.10 (95% CI: 2.40-6.94) after adjustment for immobilization and infection and was further attenuated to 3.31 (95% CI: 1.83-5.96) when additionally adjusted for trauma, blood transfusion, and central venous catheter. In a mediation analysis, 51.4% (95% CI: 35.5-79.7%) of the effect of surgery on VTE risk could be mediated through immobilization and infection. Conclusions Major surgery was a trigger for VTE, but the association between surgery and VTE risk was in part explained by other VTE triggers often coexisting with surgery, particularly immobilization and infection.

Hand grip strength in venous thromboembolism: risk of recurrence and mortality.

Background: There is limited information on the relationship between muscle strength and recurrence and mortality after incident venous thromboembolism (VTE). Objectives: To investigate whether weak hand grip strength (HGS) was associated with risk of recurrence and mortality in patients with VTE recruited from the general population. Methods: Participants from the Tromsø Study with a first-time VTE (n = 545) were included, and all VTE recurrences and deaths among the participants were recorded in the period 1994 to 2020. Weak HGS was defined as lowest 25th percentile of the general population, and incidence rates for VTE recurrence and mortality according to weak vs normal (>25th percentile) HGS, with 95% CIs, were estimated. Results: There were 90 recurrences and 350 deaths during a median of 3.7 years of follow-up. The fully adjusted hazard ratio (HR) for overall VTE recurrence for those with weak HGS vs those with normal HGS was 2.02 (95% CI, 1.23-3.30). The corresponding HRs for recurrence were 2.22 (95% CI, 1.18-4.17) in patients with a first deep vein thrombosis and 1.60 (95% CI, 0.72-3.57) in patients with a first pulmonary embolism. The cumulative 1-year survival was 74.9% and 77.8% in those with weak and normal HGS, respectively. For overall mortality after incident VTE, the fully adjusted HR for those with weak HGS was 1.34 (95% CI, 1.04-1.72). Conclusion: Weak HGS was associated with an increased risk of recurrent VTE, and the association appeared to be particularly pronounced after incident deep vein thrombosis. There was a slightly lower survival probability among those with weak HGS than among those with normal HGS.

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.

Incidence of bleeding and recurrence in isolated distal deep vein thrombosis: findings from the Venous Thrombosis Registry in Østfold Hospital.

BACKGROUND: Isolated distal deep vein thrombosis (IDDVT) is a common presentation of deep vein thrombosis. There are limited data on the long-term risk of recurrence after IDDVT. OBJECTIVES: We aimed to determine the short- and long-term incidence of venous thrombosis (VTE) recurrence after cessation of anticoagulation and the 3-month incidence of bleeding during anticoagulant treatment in patients with IDDVT. METHODS: Between January 2005 and May 2020, 475 patients with IDDVT and without active cancer were identified from the Venous Thrombosis Registry in Østfold Hospital, which is an ongoing registry of consecutive patients with VTE at Østfold Hospital, Norway. Major and clinically relevant, nonmajor bleeding as well as recurrent VTE were registered, and the cumulative incidences of these events were assessed. RESULTS: The median age of the patients was 59 years (IQR, 48-72 years), 243 (51%) patients were women, and 175 events (36.8%) were classified as unprovoked. The 1-, 5-, and 10-year cumulative incidences of recurrent VTE were 5.6% (95% CI, 3.7-8.4), 14.7% (95% CI, 11.1-19.4), and 27.2% (95% CI, 21.1-34.5), respectively. The recurrence rates were higher for unprovoked IDDVT than for provoked IDDVT. Among the recurrent events, 18 (29%) were pulmonary embolisms and 21 (33%) were proximal deep vein thromboses. The 3-month cumulative incidence of major bleeding was 1.5% (95% CI, 0.7-3.1) overall and 0.8% (95% CI, 0.2-3.1) when restricted to patients treated with direct oral anticoagulants. CONCLUSION: Despite initial treatment, the long-term risk of VTE recurrence after first-time IDDVT is high. The bleeding rates during anticoagulation, particularly with direct oral anticoagulants, were acceptably low.

Diagnostic Blood Biomarkers for Acute Pulmonary Embolism: A Systematic Review.

(1) Background: The current diagnostic algorithm for acute pulmonary embolism (PE) is associated with the overuse of CT pulmonary angiography (CTPA). An additional highly specific blood test could potentially lower the proportion of patients with suspected PE that require CTPA. The aim was to summarize the literature on the diagnostic performance of biomarkers of patients admitted to an emergency department with suspected acute PE. (2) Methods: Medline and Embase databases were searched from 1995 to the present. The study selection process, data extraction, and risk of bias assessment were conducted by two reviewers. Eligibility criteria accepted all blood biomarkers except D-dimer, and CTPA was used as the reference standard. Qualitative data synthesis was performed. (3) Results: Of the 8448 identified records, only 6 were included. Eight blood biomarkers were identified, of which, three were investigated in two separate studies. Red distribution width and mean platelet volume were reported to have a specificity of ≥ 90% in one study, although these findings were not confirmed by other studies. The majority of the studies contained a high risk of selection bias. (4) Conclusions: The modest findings and the uncertain validity of the included studies suggest that none of the biomarkers identified in this systematic review have the potential to improve the current diagnostic algorithm for acute PE by reducing the overuse of CTPA.

Plasma levels of P-selectin and future risk of incident venous thromboembolism.

BACKGROUND: P-selectin levels are elevated following acute deep vein thrombosis and reported to predict recurrent venous thromboembolism (VTE) and cancer-associated VTE. Yet, it is unknown whether plasma P-selectin levels are associated with incident VTE. OBJECTIVES: We aimed to investigate the association between plasma P-selectin levels and risk of future incident VTE. METHODS: We performed a nested case-control study in 415 patients with VTE and 843 age- and sex-matched controls derived from the general population (Tromsø IV Study). Plasma P-selectin levels were measured using enzyme-linked immunosorbent assay. Logistic regression models were used to estimate odds ratios (ORs) for VTE across quartiles of plasma P-selectin level. Sex-stratified analysis was also performed. RESULTS: Plasma P-selectin levels were higher in men (41.4 ng/mL) than in women (38.7 ng/mL, p = .0046). We found no association between plasma P-selectin levels and risk of VTE in the overall analyses. However, sex-stratified analyses revealed that women with P-selectin levels in the highest quartile (>44.3 ng/mL) had higher risk of VTE (OR, 1.63; 95% CI, 1.01-2.64) than women with P-selectin levels in the lowest quartile (≤29.9 ng/mL). In contrast, higher levels of P-selectin were apparently associated with lower risk of VTE in men (OR for highest vs lowest quartile of P-selectin, 0.69; 95% CI, 0.42-1.15). The observed associations were stronger when the time between blood sampling and VTE was shorter. CONCLUSION: Elevated levels of plasma P-selectin were associated with increased risk of VTE in women but not in men, suggesting a differential impact of sex on the association between P-selectin and VTE risk.

Survival after cancer-related venous thrombosis: the Scandinavian Thrombosis and Cancer Study.

Patients with cancer have an increased risk of developing venous thromboembolism (VTE), and this combination is reported to result in poorer survival compared with cancer alone. This study aimed to investigate the impact of VTE on the survival of patients with cancer in a general population. The Scandinavian Thrombosis and Cancer (STAC) cohort, a population-based cohort including 144 952 participants without previous VTE or cancer, was used. During follow-up, cancer and VTE incidences were registered. "Cancer-related VTE" was defined as VTE diagnosed in patients with overt or occult cancer. The survival of participants without cancer and/or VTE ("disease-free") was compared with the survival of participants with cancer and cancer-related VTE. Cox regression models with cancer and VTE as time-varying exposures were performed to calculate hazard ratios for death. Subanalyses were performed across cancer types and stages and VTE type (deep vein thrombosis or pulmonary embolism). During follow-up (mean, 11.7 years), 14 621 participants developed cancer, and 2444 developed VTE, of which 1241 were cancer-related. The mortality rates (per 100 person years) for disease-free participants, VTE only, cancer only, and cancer-related VTE were 0.63, 5.0, 9.2, and 45.3, respectively. Compared with patients with cancer only, the risk of death for patients with cancer-related VTE was increased 3.4-fold. Within all cancer types, the occurrence of VTE increased the mortality risk 2.8- to 14.7-fold. In a general population, patients with cancer with VTE had a 3.4-fold higher mortality risk than patients with cancer without VTE, independent of cancer type.

High plasma levels of C1-inhibitor are associated with lower risk of future venous thromboembolism.

BACKGROUND: C1-inhibitor (C1INH) is a broad-acting serine protease inhibitor with anticoagulant activity. The impact of C1INH plasma levels within the normal physiological range on risk of venous thromboembolism (VTE) is unknown. We assessed the association of plasma C1INH levels and VTE risk and evaluated the impact of C1INH on thrombin and plasmin generation in ex vivo assays. METHODS: A nested case-control study with 405 patients with VTE and 829 age- and sex-matched controls was derived from the Tromsø Study. Odds ratios (ORs) with 95% confidence intervals (95% CI) for VTE were estimated across plasma C1INH quartiles. Genetic regulation of C1INH was explored using quantitative trait loci analysis of whole exome sequencing data. The effect of plasma C1INH levels on coagulation was evaluated ex vivo by calibrated automated thrombography. RESULTS: Individuals with C1INH levels in the highest quartile had a lower risk of VTE (OR 0.68, 95% CI: 0.49-0.96) compared with those with C1INH in the lowest quartile. In subgroup analysis, the corresponding ORs were 0.60 (95% CI: 0.39-0.89) for deep vein thrombosis and 0.85 (95% CI: 0.52-1.38) for pulmonary embolism, respectively. No significant genetic determinants of plasma C1INH levels were identified. Addition of exogenous C1INH to normal human plasma reduced thrombin generation triggered by an activator of the intrinsic coagulation pathway, but not when triggered by an activator of the extrinsic coagulation pathway. CONCLUSIONS: High plasma levels of C1INH were associated with lower risk of VTE, and C1INH inhibited thrombin generation initiated by the intrinsic coagulation pathway ex vivo.

Low D-dimer levels at diagnosis of venous thromboembolism are associated with reduced risk of recurrence: data from the TROLL registry.

BACKGROUND: Venous thromboembolism (VTE) is a frequent disease with a high risk of recurrence. It has been suggested that the D-dimer level at the time of VTE diagnosis can be used to identify patients at a low risk of recurrence. OBJECTIVES: We aimed to investigate the impact of D-dimer levels measured at the time of VTE diagnosis on the risk of recurrence in a large cohort of patients with a first-time VTE. METHODS: The study included 2585 patients with first symptomatic non-cancer-associated VTE from the Venous Thrombosis Registry in Østfold Hospital (TROLL) (2005-2020). All recurrent events during the follow-up were recorded, and cumulative incidences of recurrence were estimated according to D-dimer levels of ≤1900 ng/mL (≤25th percentile) and >1900 ng/mL. RESULTS: During a median follow-up of 3.3 years, 395 patients experienced a recurrent VTE. The 1- and 5-year cumulative incidences of recurrence were 2.9% (95% CI: 1.8-4.6) and 11.4% (95% CI: 8.7-14.8), respectively, in those with a D-dimer concentration of ≤1900 ng/mL and 5.0% (95% CI, 4.0-6.1) and 18.3% (95% CI: 16.2-20.6), respectively, in those with a D-dimer concentration of >1900 ng/mL, respectively. In patients with unprovoked VTE, the 5-year cumulative incidence was 14.3% (95% CI: 10.3-19.7) in the ≤1900-ng/mL category, and 20.2% (95% CI: 17.3-23.5) in the >1900-ng/mL category. CONCLUSIONS: D-dimer levels within the lowest quartile, measured at the time of VTE diagnosis, were associated with lower recurrence risk. Our findings imply that D-dimer levels measured at the time of diagnosis may be used to identify patients with VTE at a low risk of recurrent VTE.

Complement factors B, D, C3bBbP and risk of future venous thromboembolism.

The complement system appears to be involved in the pathogenesis of venous thromboembolism (VTE). We investigated the association of complement factors (CF) B, D, and the alternative pathway convertase, C3bBbP, measured at inclusion, with the risk of future VTE in a nested case-control study; 380 VTE patients and 804 age- and sex-matched controls derived from the Tromsø study. Odds ratios (ORs) with 95% confidence intervals (95% CI) for VTE across tertiles of CF concentrations were estimated using logistic regression. There was no association between CFB or CFD and risk of future VTE. Higher levels of C3bBbP gave an increased risk of provoked VTE; subjects in Q4 had a 1.68-fold higher OR compared with Q1 in the age-, sex- and BMI-adjusted model (OR 1.68; 95% CI 1.08-2.64). There was no increased risk of future VTE in individuals with higher levels of complement factors B or D of the alternative pathway. Increased levels of the alternative pathway activation product, C3bBbP, showed an association with future risk of provoked VTE.