ACR Appropriateness Criteria(®) on suspected lower extremity deep vein thrombosis

Deep venous thrombosis (DVT) diagnostics: gleaning insights from point-of-care ultrasound (PoCUS) techniques in emergencies: a systematic review and meta-analysis

BACKGROUND

The assessment of deep venous thrombosis (DVT) is clinically difficult diagnosis. The "gold standard test" for DVT diagnosis is venography; however, various point-of-care ultrasound (POCUS) protocols have been suggested for DVT evaluation in the emergency department.

AIMS

This review evaluated the role of different POCUS protocols in diagnosing DVT in the emergency department.

METHODS

A systematic review and meta-analysis was conducted based of PRISMA guideline and registered on PROSEPRO (CRD42023398871). An electronic database search in Embase, PubMed, ScienceDirect, and Google scholar and a manual search were performed to identify eligible studies till February 2023. Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2) was used to assess the risk of bias in included studies. Quantitative analysis was carried out using STATA 16 and Review Manager software (RevMan 5.4.1). Sensitivity, specificity of POCUS protocols for DVT diagnosis compared to reference standard test was calculated.

RESULTS

Heterogeneity was identified between 26 included studies for review. The pooled sensitivity, specificity, PPV, and NPV for the 2-point POCUS protocol were 92.32% (95% CI: 87.58-97.06), 96.86% (95% CI: 95.09-98.64), 88.41% (95% CI: 82.24-94.58) and 97.25% (95% CI: 95.51-98.99), respectively. Similarly, the pooled sensitivity, specificity, PPV, and NPV for 3-point POCUS were 89.15% (95% CI: 83.24-95.07), 92.71% (95% CI: 89.59-95.83), 81.27% (95% CI: 73.79-88.75), and 95.47% (95% CI: 92.93-98). The data pooled for complete compression ultrasound, and whole-leg duplex ultrasound also resulted in a sensitivity and specificity of 100% (95% CI: 98.21-100) and 97.05% (95% CI: 92.25-100), respectively. On the other hand, the time from triage to DVT diagnosis was significantly shorter for emergency physician-performed POCUS than diagnostic tests performed by radiologists.

CONCLUSION

The diagnostic performance of POCUS protocols performed by emergency physicians was excellent. Combined with the significant reduction in time to diagnosis. POCUS can be used as the first-line imaging tool for DVT diagnosis in the emergency department. We also recommended that attending emergency physicians with POCUS training are present during DVT diagnosis to improve diagnostic performance even though high diagnostic performance is observed even with the minimum training.

Low-density lipoprotein cholesterol-to-lymphocyte count ratio (LLR) is a promising novel predictor of postoperative new-onset deep vein thrombosis following open wedge high tibial osteotomy: a propensity score-matched analysis

BACKGROUND

The association of low-density lipoprotein cholesterol (LDL-C) and lymphocyte counts with the development of deep vein thrombosis (DVT) has been demonstrated in many fields but remains lacking in open wedge high tibial osteotomy (OWHTO). This study aimed to assess the predictive value of LDL-C to lymphocyte count ratio (LLR) in screening for postoperative new-onset DVT.

METHODS

Clinical data were retrospectively collected from patients who underwent OWHTO between June 2018 and May 2023. The limited restricted cubic spline (RCS) was conducted to evaluate the nonlinear relationship between LLR and the risk of postoperative new-onset DVT. The receiver operating characteristic (ROC) curves were plotted and the predictive value of biomarkers was assessed. After adjusting for intergroup confounders by propensity score matching, the univariate logistic regression was applied to assess the association between LLR and DVT.

RESULTS

1293 eligible patients were included. RCS analysis showed a linear positive correlation between LLR and the risk of DVT (P for overall = 0.008). We identified LLR had an area under the curve of 0.607, accuracy of 74.3%, sensitivity of 38.5%, and specificity of 80.7%, and LLR > 1.75 was independently associated with a 1.45-fold risk of DVT (95% CI: 1.01-2.08, P = 0.045). Furthermore, significant heterogeneities were observed in the subgroups of age, BMI, diabetes mellitus, hypertension, Kellgren-Lawrence grade, the American Society of Anesthesiologists (ASA) score, and intraoperative osteotomy correction size.

CONCLUSION

LLR is a valuable biomarker for predicting postoperative new-onset DVT in patients with OWHTO, and routine screening is expected to yield positive benefits.

Meta-analysis of dichotomous and ordinal tests with an imperfect gold standard

Standard methods for the meta-analysis of medical tests, without assuming a gold standard, are limited to dichotomous data. Multivariate probit models are used to analyse correlated dichotomous data, and can be extended to model ordinal data. Within the context of an imperfect gold standard, they have previously been used for the analysis of dichotomous and ordinal test data from a single study, and for the meta-analysis of dichotomous tests. However, they have not previously been used for the meta-analysis of ordinal tests. In this article, we developed a Bayesian multivariate probit latent class model for the simultaneous meta-analysis of ordinal and dichotomous tests without assuming a gold standard, which also allows one to obtain summary estimates of joint test accuracy. We fitted the models using the software Stan, which uses a state-of-the-art Hamiltonian Monte Carlo algorithm, and we applied the models to a dataset in which studies evaluated the accuracy of tests, and test combinations, for deep vein thrombosis. We demonstrate the issues with dichotomising ordinal test accuracy data in the presence of an imperfect gold standard, before applying and comparing several variations of our proposed model which do not require the data to be dichotomised. The models proposed will allow researchers to more appropriately meta-analyse ordinal and dichotomous tests without a gold standard, potentially leading to less biased estimates of test accuracy. This may lead to a better understanding of which tests, and test combinations, should be used for any given medical condition.

Incidence of and risk factors for deep vein thrombosis in patients undergoing osteotomies around the knee: comparative analysis of different osteotomy types

PURPOSE

To examine the incidence of and risk factors for deep vein thrombosis (DVT) among different types of osteotomies around the knee. It was hypothesized that DVT would be detected at a substantial rate after the osteotomy, and there would be differences in the incidences among the different osteotomy procedures.

METHODS

Consecutive patients who underwent knee osteotomies for varus osteoarthritis and met the inclusion criteria were included in the study. Ultrasonographic evaluation was performed to detect DVT on bilateral whole leg at 1 month before and 7 days after surgery. Statistical comparison of the demographic and clinical parameters between the patients with and without DVT as well as multivariate analysis using logistic regression was conducted to identify risk factors related to the incidence of postoperative DVT.

RESULTS

The study subjects comprised 159 knees in 135 patients with medial opening wedge high tibial osteotomy (MOW-HTO), 93 knees in 78 patients with lateral closed wedge high tibial osteotomy (LCW-HTO), and 74 knees in 54 patients with double level osteotomy (DLO). In the postoperative evaluation, DVT was detected in 19 of 159 knees (11.9%) in MOW-HTO, 21 of 93 knees (22.6%) in LCW-HTO, and 5 of 74 knees (6.8%) in DLO. The incidence of DVT was significantly higher after LCW-HTO than after MOW-HTO and DLO (p < 0.01). DVT at a level above the knee was noted in one case after MOW-HTO, while DVT in the remaining cases developed at a level below the knee. No cases of symptomatic pulmonary embolism were encountered during the study period. Among the potential risk factors assessed for correlation with the incidence of DVT, LCW-HTO was identified as a significant risk factor (odds ratio: 2.54; 95% CI 1.334-4.836; p < 0.01).

CONCLUSIONS

This study demonstrated that DVT occurred at a substantial rate (overall incidence of 13.8%) after osteotomy around the knee even with the use of prophylactic anticoagulant. Among the different osteotomy types, the DVT rate was significantly higher after LCW-HTO than after MOW-HTO and DLO.

LEVEL OF EVIDENCE

Prospectively designed observational cohort study, Level III.

Risk factor for venous thromboembolism after high tibial osteotomy -analysis of patient demographics, medical comorbidities, operative valuables, and clinical results

Purpose

The aim of this study was to investigate risk factors for VTEs after HTO based on patient demographics, medical comorbidities, operative valuables, and clinical results.

Methods

A total of 137 patients were assessed VTEs using ultrasonography at 1 week after HTO. The risk factors for postoperative VTEs were to assessed.

Results

The incidence of VTEs after HTO was 25.5%. Postoperative single leg standing test was independent predictors of VTEs after HTO.

Conclusion

The incidence of VTEs after HTO is relatively high and Postoperative knee function is important for preventing VTEs after HTO.

Level of evidence

Ⅱ, Prospective comparative study.

Endovascular Treatment for Lower Extremity Deep Vein Thrombosis: An Overview

Lower extremity deep vein thrombosis (DVT) is a serious medical condition that can result in local pain and gait disturbance. DVT progression can also lead to death or major disability as a result of pulmonary embolism, postthrombotic syndrome, or limb amputation. However, early thrombus removal can rapidly relieve symptoms and prevent disease progression. Various endovascular procedures have been developed in the recent years to treat DVT, and endovascular treatment has been established as one of the major therapeutic methods to treat lower extremity DVT. However, the treatment of lower extremity DVT varies according to the disease duration, location of affected vessels, and the presence of symptoms. This article reviews and discusses effective endovascular treatment methods for lower extremity DVT.

Time-efficient and contrast-free magnetic resonance imaging approach to the diagnosis of deep vein thrombosis on black-blood gradient-echo sequence: a pilot study

Background

Black-blood thrombus imaging (BTI) has shown to be advantageous for the diagnosis of deep vein thrombosis (DVT). However, previous techniques using fast spin echo have a high specific absorption rate. As DANTE (delay alternating with nutation for tailored excitation) black-blood preparation can suppress blood flows over a broad range of velocities, we hypothesized that a DANTE black-blood preparation combined with a fast low-angle shot (FLASH) gradient-echo readout-DANTE-FLASH could be used to diagnose DVT.

Methods

Eleven healthy volunteers and 30 suspected DVT patients were recruited to undergo DANTE-FLASH and magnetic resonance direct thrombus imaging (MRDTI). The suspected DVT patients were also examined by ultrasound (US). For the segment level, a total of 1,066 venous vessel segments were analyzed. Using US and MRDTI as the references, the sensitivity (SE), specificity (SP), positive and negative predictive values (PPV and NPV), and accuracy (ACC) of DANTE-FLASH were calculated. To quantitatively compare image quality between DANTE-FLASH and MRDTI, image signal-to-noise ratio (SNR), apparent contrast-to-noise ratio (CNR) between muscle and the venous lumen, and the apparent CNR between the thrombus and venous lumen were measured. Additionally, diagnostic confidence, image quality, and clot burden were also evaluated.

Results

Using the consensus results of US and MRDTI as a standard reference, the diagnostic SE, SP, PPV, NPV, and ACC of DANTE-FLASH for the 2 readers were 97.0% and 93.2%, 99.0% and 98.2%, 93.4% and 87.9%, 99.6% and 99.0%, and 98.8% and 97.6%, respectively. According to the image quantitative analysis results, DANTE-FLASH demonstrated higher image SNR and CNR than MRDTI. The image quality and diagnostic confidence scores of DANTE-FLASH were higher than MRDTI (3.66±0.44 vs. 3.52±0.52, P<0.001, and 3.84±0.36 vs. 3.76±0.41, P<0.001). There was excellent agreement between DANTE-FLASH and MRDTI on clot burden evaluation.

Conclusions

DANTE-FLASH provided better image quality than MRDTI and accurately detected thrombi. It may, therefore, serve as a safe and convenient alternative for the diagnosis of DVT.

CT IVC venogram: normalized quantitative criteria for patency and thrombosis

PURPOSE

Establish normal attenuation ratios for vein to artery on CT IVC venogram and determine a vascular attenuation ratio diagnostic of thrombus.

METHODS

This retrospective, HIPAA-compliant study included 56 CT IVC venograms. Images were reviewed for the presence of femoral vein or IVC thrombus. Attenuation ratios for each vein and its corresponding artery were calculated by two observers and averaged in four venous stations (right and left femoral veins, and IVC at the confluence of the iliac veins and at the left renal vein). The reference standard for the absence of thrombus was clinical follow-up and for the presence of thrombus it was thrombectomy or catheter venogram. Receiver operating characteristic (ROC) analysis was performed using ratios from one venous station and threshold for thrombus was determined using the Youden's index.

RESULTS

36 of 56 CTs demonstrated no thrombus. 20 CTs demonstrated thrombus, confirmed in eight patients. For CTs with no thrombus, median ratios among the venous stations ranged from 0.89 (IQR 0.83-0.93) to 0.91 (IQR 0.86-0.94). ROC analysis of ratios from a single representative station (left femoral vein, n = 4 confirmed clots) demonstrated an area under the curve (AUC) of 0.994 (p = 0.001) and a threshold of 0.67 for diagnosing thrombus [sensitivity 100% (95% CI 39.76-100%), specificity 97.5% (86.84-99.94%)].

CONCLUSION

The normal attenuation ratio of vein to artery in the absence of venous thrombus on a 3-min delay CT IVC venogram is approximately 0.91. A ratio less than 0.67 is highly suggestive of thrombus.

Effect of miR-495 on lower extremity deep vein thrombosis through the TLR4 signaling pathway by regulation of IL1R1

Lower extremity deep vein thrombosis (LEDVT), a common peripheral vascular disease caused by a blood clot in a deep vein is usually accompanied by swelling of the lower limbs. MicroRNAs (miRs) have been reported to play roles in LEDVT. We aimed to investigate the effect of miR-495 on LEDVT via toll-like receptor 4 (TLR4) signaling pathway through interleukin 1 receptor type 1 (IL1R1). LEDVT mouse model was established, and the femoral vein (FV) tissues were collected to detect expressions of miR-495, IL1R1, and TLR4 signaling-related genes. The expressions of both CD31 and CD34 (markers for endothelial progenitor cells) in the FV endothelial cells as well as the proportion of CD31⁺/CD34⁺ cells in peripheral blood were measured in order to evaluate thrombosis. The effect of miR-495 on cell viability, cell cycle, and apoptosis was analyzed. IL1R1 was confirmed as the target gene of miR-495. Besides, inhibiting the miR-495 expression could increase IL1R1 expression along with activating the TLR4 signaling pathway. The total number of the leukocytes along with the ratio of weight to length of thrombus in the FV tissue showed an increase. The overexpression of miR-495 could promote FV endothelial cell viability. By injecting agomiR-495 and antagomiR-495 in vivo, the number of leukocytes in the FV tissues and the ratio of weight to length of thrombus were significantly decreased in the mice injected with the overexpressed miR-495, and the IL1R1/TLR4 signaling pathway was inhibited. Collectively, overexpressed miR-495 directly promotes proliferation while simultaneously inhibiting apoptosis of FV endothelial cells, alleviating FV thrombosis by inhibiting IL1R1 via suppression of TLR4 signaling pathway.

Deep vein thrombosis: pathogenesis, diagnosis, and medical management

Deep vein thrombosis (DVT) is a major preventable cause of morbidity and mortality worldwide. Venous thromboembolism (VTE), which includes DVT and pulmonary embolism (PE), affects an estimated 1 per 1,000 people and contributes to 60,000-100,000 deaths annually. Normal blood physiology hinges on a delicate balance between pro- and anti-coagulant factors. Virchow's Triad distills the multitude of risk factors for DVT into three basic elements favoring thrombus formation: venous stasis, vascular injury, and hypercoagulability. Clinical, biochemical, and radiological tests are used to increase the sensitivity and specificity for diagnosing DVT. Anticoagulation therapy is essential for the treatment of DVT. With few exceptions, the standard therapy for DVT has been vitamin K-antagonists (VKAs) such as warfarin with heparin or fractionated heparin bridging. More recently, a number of large-scale clinical trials have validated the use of direct oral anticoagulants (DOACs) in place of warfarin in select cases. In this review, we summarize the pathogenesis, diagnosis, and medical management of DVT, with particular emphasis on anticoagulation therapy and the role of DOACs in the current treatment algorithm.

Association of interleukin-18 gene polymorphism and its protein expression with the lower extremity deep venous thrombosis in the chinese han population: A case-control study

OBJECTIVE

We aim to explain the correlation among IL-18 gene polymorphism, its protein expression and LEDVT in the Chinese Han population.

METHODS

A total of 138 LEDVT patients and 150 healthy people volunteered as LEDVT and control groups. All the data, including the gender, age, BMI, levels of TG, LDL/HDL, TC, GLU, APTT, BUN, Cr, ALT, AST, ApoA1, ApoB, and Fg was detected. IL-18 level, IL-18 -137G/C and -607C/A polymorphism, and risk factors of LEDVT were detected using ELISA, PCR-RFLP and multivariate logistic regression analysis, respectively.

RESULTS

Increased BMI, GLU, Fg, BUN, ApoB and IL-18 and decreased APTT were found in the LEDVT group. The GC + CC genotype and C allele in -137G/C polymorphism was elevated in the control group when compared to that in the LEDVT group. The IL-18 level was elevated in the case group when compared to the control group with respect to the same genotype in -607C/A and -137G/C polymorphisms, and in the LEDVT group, IL-18 level was higher in the GG genotype than that in the GC + CC genotype of -137G/C polymorphism. BUN, GG genotype and IL-18 level were independent risk factors, but APTT was a protective factor of LEDVT.

CONCLUSION

On the basis of our results, we concluded that the GG genotype of -137G/C polymorphism and IL-18 level are independent risk factors of LEDVT, and IL-18 gene polymorphism affects the level of IL-18 in LEDVT patients.

Association Between the Lower Extremity Deep Venous Thrombosis, the Warfarin Maintenance Dose, and CYP2C9*3, CYP2D6*10, and CYP3A5*3 Genetic Polymorphisms: A Case-Control Study

OBJECTIVE

This study explored the association between the CYP2C9*3/CYP2D6*10/CYP3A5*3 genetic polymorphisms with lower extremity deep venous thrombosis (LEDVT) and the warfarin maintenance dose.

METHODS

Five hundred thirty-six patients who were pathologically diagnosed with LEDVT after surgery were included in the LEDVT group. At the same time, 540 patients without LEDVT who underwent surgery were recruited as the control group. Patients were given warfarin at an initial dose of 2.5-3.0 mg. Blood samples were collected to detect the initial and stable international normalized ratio (INR) values. The warfarin maintenance dose was obtained if the INR remained within a range of 2.0-3.0 for 3 consecutive days. The genotype distribution and haplotype analysis of the CYP2C9*3/CYP2D6*10/CYP3A5*3 alleles were analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) testing and SHEsis software, respectively. Logistic regression analysis was used to analyze the risk and protective factors for LEDVT.

RESULTS

The A/G genotypes, G/G genotypes, and G allele of CYP3A5*3 in the LEDVT group were observed with increased frequency compared with the control group. The LEDVT group displayed a higher ACG haplotype frequency, and lower ACA and ATA haplotype frequencies than the control group. Age, diabetes, low-density lipoprotein, CYP3A5*3 and the ACG haplotype were independent risk factors for LEDVT. High-density lipoprotein and the ACA haplotype were independent protective factors for LEDVT. The genotype distributions of the CYP2C9*3, CYP2D6*10, and CYP3A5*3 genetic polymorphisms were associated with the warfarin maintenance dose.

CONCLUSION

The CYP3A5*3 genetic polymorphism may be an important risk factor for LEDVT. Moreover, CYP2C9*3, CYP2D6*10, and CYP3A5*3 are associated with the warfarin maintenance dose.

Clues to vascular disorders at non-contrast CT of the chest, abdomen, and pelvis

Non-contrast chest CT scans are commonly performed while CT scans of the abdomen and pelvis are performed in a select subset of patients; those with limited renal function, an allergy to iodinated contrast, in the setting of suspected renal calculus, retroperitoneal hematoma, common duct calculus, abdominal aortic aneurysm with or without rupture, and in patients undergoing a PET-CT scan. In the absence of intravenous contrast, vascular structures may prove challenging to evaluate, yet their assessment is an important component of every non-contrast CT examination. We describe the key imaging features of both arterial and venous pathology, and review clues and common associated non-vascular findings, which can help the radiologist identify vascular disorders at non-contrast CT. Briefly, alternative imaging options are discussed.

Unexpected Findings During Evaluation of Acute Pelvic Pain With Transvaginal Sonography

Transvaginal sonography is the first-line imaging modality used to evaluate acute female pelvic pain in the emergency setting because of its accessibility, lack of ionizing radiation, and excellent ability to identify reproductive tract disorders. Although the intent of transvaginal sonography is to evaluate the reproductive organs, imaging of adjacent pelvic structures is an important part of every transvaginal sonographic examination. Gastrointestinal, urologic, and vascular disorders incidentally scanned on transvaginal sonography may explain the pain for which the examination is being performed. In such cases, transvaginal sonography may play an important role in the diagnostic process if the clinician is aware of the transvaginal sonographic appearance of these entities.

Diagnosis and Treatment of Lower Extremity Deep Vein Thrombosis: Korean Practice Guidelines

Lower extremity deep vein thrombosis is a serious medical condition that can result in death or major disability due to pulmonary embolism or post-thrombotic syndrome. Appropriate diagnosis and treatment are required to improve symptoms and salvage the affected limb. Early thrombus clearance rapidly resolves symptoms related to venous obstruction, restores valve function and reduces the incidence of post-thrombotic syndrome. Recently, endovascular treatment has been established as a standard method for early thrombus removal. However, there are a variety of views regarding the indications and procedures among medical institutions and operators. Therefore, we intend to provide evidence-based guidelines for diagnosis and treatment of lower extremity deep vein thrombosis by multidisciplinary consensus. These guidelines are the result of a close collaboration between interventional radiologists and vascular surgeons. The goals of these guidelines are to improve treatment, to serve as a guide to the clinician, and consequently to contribute to public health care.

Risk assessment of deep-vein thrombosis after acute stroke: a prospective study using clinical factors

AIMS

Deep-vein thrombosis (DVT) represents a serious complication in acute stroke patients with pulmonary embolus (PE) as a potential outcome. Prediction of DVT may help with formulating a proper prevention strategy. To assess of the risk of deep venous thrombosis (DVT) in acute stroke patients, we developed and validated a clinical score in a cohort study.

METHODS

Incidence of Deep Venous Thrombosis after Acute Stroke in China (INVENT-China) is a multicenter prospective cohort study. The potential predictive variables for DVT at baseline were collected, and the presence of DVT was evaluated using ultrasonography on the 14 ± 3 days. Data were randomly assigned to either a training data set or a test data set. Multivariate logistic regression analysis was used to develop risk scores to predict DVT in the training data set and the area under the receiver operating characteristic curve to validate the score in the test data set.

RESULTS

From 2006-2007, 862 hospital-based acute stroke patients were enrolled in China. The overall incidence of DVT after acute stroke within two weeks was 12.4% (95%CI 10.3-14.7%). A seven-point score derived in the training data set (age [≥65 years = 1], sex [female gender = 1]), obesity [BMI ≥ 25 kg/m(2) = 1], active cancer [yes = 2], stroke subtype [cerebral hemorraghe = 1], muscle weakness [≥2 on Lower limb NIHSS score = 1] was highly predictive of 14-day risk of DVT(c statistic = 0.70, 95% CI, 0.64-0.76, P < 0.001), in the overall study population(c statistic = 0.65, 95% CI 0.59-0.70, P < 0.001).

CONCLUSIONS

This clinical score may help identify acute stroke patients with high risk of DVT. In addition, it also serves as a platform to develop further models of DVT prediction in stroke patients based on clinical factors.

The incidence of pulmonary embolism and deep vein thrombosis after knee arthroplasty in Asians remains low: a meta-analysis

BACKGROUND

While Western literature has mostly reported the incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) after TKA with chemoprophylaxis, the Asian literature still has mostly reported the incidence without chemoprophylaxis. This may reflect a low incidence of DVT and PE in Asian patients, although some recent studies suggest the incidence after TKA in Asian patients is increasing. Moreover, it is unclear whether the incidence of DVT and PE after TKA is similarly low among different Asian countries.

QUESTIONS/PURPOSES

We therefore determined the overall incidence of symptomatic PE and DVT without chemoprophylaxis after TKA in the Asian population, determined whether the incidence had a tendency to increase over time in Asia, and compared the incidence of symptomatic PE and DVT among Asian countries through a meta-analysis.

METHODS

We searched the PubMed, Embase, Cochrane Library, Web of Science, and Google Scholar websites for prospective studies published between 1996 and 2011. A total of 1947 patients from 18 studies were reviewed for meta-analysis.

RESULTS

The incidence of symptomatic PE was 0.01%. The incidences of overall DVT, proximal DVT, and symptomatic DVT were 40.4%, 5.8% and 1.9%, respectively. We found no difference in incidence of symptomatic PE among Asian countries and no trends in changes of the incidence over time.

CONCLUSIONS

The incidence of symptomatic PE and DVT after TKA without prophylaxis is low in Asian countries and has not changed over time, despite Westernizing lifestyles and an aging populace. Further investigation with large randomized studies is necessary to confirm our findings and identify risk factors predisposing to DVT.