The goal of this observational study is to evaluate the predictive efficacy of the Modified Caprini Risk Assessment Score and D-Dimer in identifying and managing lower extremity venous thrombosis (LEVT) among cardiothoracic surgery patients in Baghdad. The main questions it aims to answer are:

Does combining the Modified Caprini Score with D-Dimer improve the accuracy of predicting lower extremity venous thrombosis (LEVT) compared to using each tool independently? Can these tools effectively guide clinical decisions for lower extremity venous thrombosis (LEVT) prevention and management in this patient population?

Participants will:

Undergo risk assessment for lower extremity venous thrombosis (LEVT) using the Modified Caprini Score and have their D-Dimer levels measured during their hospital stay.

Be monitored for clinical outcomes, including confirmed lower extremity venous thrombosis (LEVT) incidence, need for anticoagulation therapy, and complications such as pulmonary embolism or recurrent thrombosis.

Research indicates that the incidence of deep vein thrombosis (DVT) among surgical patients is notably higher than in the general population. In a review of 10,638 cardiac surgical patients, the incidence of deep vein thrombosis (DVT) was found to be 0.7% due to multiple factors, including prolonged immobility, the hypercoagulable state induced by surgical interventions, and vascular trauma associated with cardiothoracic procedures. Patients undergoing cardiac surgery may have longer hospital stays, which correlates with increased risk for deep vein thrombosis (DVT). For instance, studies indicate that the incidence of deep vein thrombosis (DVT) in patients post-cardiac surgery can be as high as 1.62%. Certain surgeries, such as coronary artery bypass grafting (CABG) and valve surgeries, have shown a higher incidence of deep vein thrombosis (DVT) compared to other surgical procedures. For example, one study found that 1.62% of patients developed deep vein thrombosis (DVT) after cardiac surgery. Procedures like thoracotomy or pneumonectomy are associated with even higher risks due to the extensive surgical trauma involved. Research has indicated that patients undergoing such surgeries may experience DVT rates as high as 34.1%.

Lower extremity venous thrombosis (LEVT) is a significant clinical concern that encompasses deep vein thrombosis (DVT) and pulmonary embolism (PE) and poses a considerable risk postoperatively. The risk of PE is especially pronounced during the first six weeks post-surgery, with studies indicating that patients are up to 70 times more likely to experience VTE during this period compared to those who have not undergone surgery The risk remains elevated beyond six weeks, albeit at a reduced level. For instance, the odds ratio for PE between weeks 7 and 12 post-surgery can be as high as 4.23 for certain surgical types. This condition represents a continuum of pathology that can lead to severe outcomes, including sudden death from PE, This is considered one of the more serious postoperative complications. Early identification and the timely use of preventive measures can prevent PE and other fatal complications.

The extensive research currently conducted on the risk factors for postoperative VTE has yielded several risk assessment models. The Caprini score is widely used across various surgical specialties to identify patients at high risk of developing VTE. Among these, the modified Caprini score is the most commonly used tool in the thoracic surgery department. D-dimer is a biomarker of fibrin formation and degradation and acts a marker of coagulation and fibrinolysis system activation. As an indirect marker of thrombosis activity, D-dimer is of great significance for checking the formation of acute venous thrombosis. Although D-dimer has high negative predictive value for DVT, it has low positive predictive value and low specificity for thrombosis The Caprini score has been validated across numerous specialties in Iraq, confirming its reliability as a predictive tool for VTE. Many hospitals in Iraq lack modern medical equipment and resources that are essential for diagnosing and treating VTE effectively. This deficiency contributes to a reliance on outdated practices and guidelines, which may not align with current best practices in VTE management The slow adoption of new technologies impedes the ability to perform accurate risk assessments and implement evidence-based protocols for VTE prophylaxis. For instance, studies indicate that healthcare providers often depend on clinical experience rather than established guidelines due to a lack of access to updated resources The aim of this study is to bridge these gaps by investigating the efficacy of using a combined approach involving the modified Caprini risk assessment score and D-dimer testing values in patients with lower extremity venous thrombosis following cardiothoracic surgery We hypothesized that the combination of these two indicators may provide better predictive value. These findings may provide the basis for the follow-up prediction and timely intervention of high-risk groups of post-surgery patients, potentially leading to better patient outcomes. This combination approach has been explored in several international studies, but its application within Iraq, specifically in Baghdad, has yet to be thoroughly examined in cardiothoracic patients.

Inclusion Criteria:

• Inpatients with a hospital stay over 3 days
• Written informed consent obtained from patients or their legal guardians.
• Availability for postoperative follow-up to assess outcomes like LEVT development or related complications.

Exclusion Criteria:

• Preexisting LEVT or Pulmonary Embolism: Diagnosed before the index surgery.
• Severe Coagulopathy: Patients with inherited or acquired bleeding disorders (e.g., hemophilia, advanced liver disease).
• receiving any anticoagulation therapy for any reason.
• patients who did not undergo a postoperative D-dimer test.
• Incomplete Data: missing essential clinical or laboratory data for Modified Caprini Score calculation or D-Dimer measurement.
• Pregnancy: pregnant women or those within six weeks postpartum.
• Noncompliance: Patients unwilling or unable to adhere to study follow-up protocols.

The study will include adult patients (≥18 years old) undergoing cardiothoracic surgery at Kadhimiya Teaching Hospital in Baghdad, with a focus on those at risk for lower extremity venous thrombosis (LEVT).