In this cross-sectional study, the incidence of venous thrombosis, sites of thrombosis, and common risk factors in hospitalized patients were analyzed and reported in order to enhance medical practitioners' understanding of the epidemiological features of venous thrombosis. And further efforts should be made to enhance the prevention and management of VTE. The results of this study indicate that the incidence of VTE in hospitalized patients was 21.0%. Our VTE incidence rate is similar to other studies[7, 22].
Many studies[16, 23] have found that distal DVT accounts for the majority of LEDVT, which is consistent with our study. Although LEDVT can originate anywhere within the deep veins of the lower limb, the theory of DVT propagation from the distal axial proximal deep venous system is widely accepted[24, 25].One study has reported a 10% rate of DVT transmission from the distal to the proximal deep venous system[26].A cohort study[27] also found a higher probability of PE in patients with proximal LEDVT, which is supported by the present study. Therefore, we need to pay more attention to distal DVT and treat it early to avoid disease progression.
This study found that PE is more commonly observed in the bilateral pulmonary arteries, followed by the right side, and less frequently on the left side, which is consistent with previous research[28].Thrombosis is a complex process involving multiple dislodgements, with emboli potentially dislodging into various pulmonary arterial segments on either side. Due to the uneven distribution of the left and right lung lobes, blood flow is greater to the right lung. Additionally, the heart’s location in the left thoracic cavity results in the left PA being positioned higher than the right at the bifurcation. Consequently, when a thrombus dislodges from the inferior deep vein and enters the left ventricle via the inferior vena cava, it is more likely to initially enter the right PA. All of these reasons lead to embolism occurring more frequently in the right PA compared to the left.
Multivariate analysis reveals that age, diabetes, prior history of VTE, CVC, limb swelling, and HGB are independent risk factors for VTE. The association of other traditional risk factors with VTE was not observed in this study, either because the study included an inpatient population with a variety of disease characteristics, diluting the effect of specific risk factors, or because the sample size for these risk factors was insufficient in the subgroup analysis, thus limiting our ability to arrive at definitive conclusions.
This study reveals that age is an independent risk factor for VTE. Previous research has also indicated that VTE is primarily a disease of middle-aged and elderly individuals, with incidence rates increasing with age[13].Coagulation factor concentrations increase with age, which may also account for the higher risk of VTE in the elderly[3].In our study, we found no significant association between gender and VTE, whereas previous research has suggested a greater impact on males[3].
A meta-analysis revealed that the risk of VTE in diabetic patients was 1.4 times higher than that in non-diabetic individuals[29], which is consistent with our findings.One mechanism for the complication of thrombosis in diabetes may be the hyperglycaemia-induced production of excess superoxide in the mitochondrial electron transport chain, which activates several damage pathways[30]. Other studies[31, 32]have also found that acute changes in glycaemia and insulin resistance in diabetic patients can exacerbate the hypercoagulable state, which in turn increases the risk of VTE. However, the determinants of VTE in diabetic patients remain unclear and require further study.
CVCs play a key role in inpatient settings, where they provide reliable central venous access for medium to long-term intravenous drug therapy. Numerous studies[33, 34]have shown a strong association between long-term CVC use and the risk of upper extremity deep vein thrombosis (UEDVT). Consistent with these findings, our study also identified CVCs as a major contributor to UEDVT. This phenomenon may be due to vascular endothelial injury caused by indwelling catheters, blood stasis and compression of cervical lymph nodes.
Most studies agree that limb swelling is a strong positive indicator of VTE [13, 35]. This study also found that both unilateral and bilateral limb swelling was an independent risk factor for VTE. This may be because VTE is an overlapping endovascular disease with similar risk factors and pathophysiology to coronary artery disease, cerebrovascular disease and peripheral arterial disease[36]. More studies are needed to validate whether bilateral limb swelling can be a screening indicator for VTE and to exclude the effects of other cardiovascular diseases. An association between heart failure and VTE has not been found in the results of the multivariate analysis. The reason for this result may be the implementation of thromboprophylaxis in patients with heart failure, and the next step could be a subgroup analysis of patients with heart failure to assess the association.
Our study found that HGB was associated with VTE, in agreement with previous studies[21]. Red blood cells are significantly involved in normal haemostasis and pathological thrombosis[37]. HGB was associated with a long-term risk of VTE.There were no significant differences observed in the WBC and PLT counts, which may be attributed to the underlying disease tendencies of hospitalized patients.
This study has a number of limitations. Firstly, this was a single-centre study that only looked at the current area. We were unable to obtain venograms, the preferred gold standard for confirming DVT, and availability was lacking in Benxi. The cross-sectional study design does not allow for the determination of the incidence of new events over time. The population enrolled was in-patients who had Doppler ultrasound, a population that is likely to be more sick (have higher baseline rates of VTE) than the general population. Our analysis of many subgroups was limited by the inadequate sample size in the group. In addition, we did not analyse treatment status in patients with VTE. Finally, we could not be certain that VTE originated in the leg, and more investigations are needed to find details in order to investigate the origin of the embolus.