With its latest paper pending publication in the Journal of Trauma and Acute Care Surgery, the Consortium of Leaders in the Study of Traumatic Thromboembolism (CLOTT) Study Group marks more than 12 years of fruitful investigation. The CLOTT Study Group began as a group of trauma surgeons with an interest in VTE after injury. Founding investigator, Peggy Knudson, MD, FACS, said the group began convening over lunch during annual AAST meetings (with support from CNTR–formerly known as the National Trauma Institute) to discuss what to study and began work on a grant that was eventually funded by the Department of Defense. “Although the initial group was small, after the index papers were completed, the data was shared widely,” she said. “That resulted in a large number of follow-on studies and an expanded group of researchers.”

The group spent months developing the data collection form in order to answer as many questions as possible. “I think this is an important lesson for future studies and for young investigators because in a prospective study, it is difficult to go back and collect data after the fact,” Dr. Knudson noted.

Arguably, the three most important discoveries to emerge from CLOTT research are:

• That pulmonary thrombi are separate from pulmonary embolism with a distinct set of risk factors and thus warranting a different treatment algorithm,
• That failure of clot lysis may be just as important as clot formation and thus introducing a potentially new pathway for treatment of unwanted clot after injury, and
• That early initiation of prophylaxis against clot is not only safe but extremely effective in all trauma patients including those with neurological and orthopedic injuries.

CLOTT Publications to date:

1. Knudson et al: Challenging Traditional Paradigms in Posttraumatic Pulmonary Thrombosis. JAMA Surg 2022 1; 157:177-186.
2. Knudson et al: Tissue Plasminogen activator resistance is an early predictor of posttraumatic venous thromboembolism. J Trauma Acute Care Surgery 2022; 93:598-603
3. Bandle JK, Shackford SF, Sise CB, Knudson MM for the CLOTT Study Group. J Trauma Acute Care Surgery. 2014; 76:213-15.
4. Godat et al: Venous thromboembolism risk after spinal cord injury. J Trauma acute care surgery 2022;94:23-29
5. Knowlton et al: Does preperitoneal packing increase venous thromboembolism risk among trauma patients? J Trauma Acute Care Surgery 2024
6. Knowlton et al: Does TXA increase VTE in Trauma? Injury 2023; 54:111008
7. Wu YT et al: Early thromboembolism prophylaxis in patients with trauma intracranial hemorrhage. J Trauma Acute Care Surg 2023;95:649-656.
8. Wu YT, Martin M et al: Early thromboembolism prophylaxis in patients undergoing neurosurgical procedures after trauma. (Accepted for publication in JTACS-open) 2026
9. Lombardo S: et al: Weight based enoxaparin thromboprophylaxis in young trauma patients. J Trauma Acute Care Surg Open (2024).
10. Rodriguez IE, Saben JL, Moore EE Knudson MM et al: : Fibrinolysis resistance after injury is a risk factor or hospital acquired pneumonia-like disease pattern. Surgical Infections 2024;25:87-94
11. Kerwin AJ, Lombarbo S, Haut ER, Knudson MM for the CLOTT Study Group: Variability of {prophylactic Inferior Vena Cava Filter use in Young Trauma Patients: Analysis of the Consortium of Leaders in the Study of Trauma Thromboembolism Database. J. Am Coll Surg; 2025;241:601-609.
12. Adraska EA, Fields A, Nunez-Garcia B, Moore EE et al: Platelet flux in trauma-associated venous thromboembolism: a secondary analysis of the CLOTT studies. J Trauma Acute Care Surgery. 2025;98:957-965.
13. Bokemkamp, M, Argandykov D, Dorken Gallastegi A, Knudson MM, Velmahos G. Early thromboprophylaxis in nonoperative blunt abdominal trauma: a CLOTT Research Study. 2025, J Trauma Acute Care Open.
14. Kerwin AJ, Byerly S, Filiberto DM, Lenart EK et al: Timing is Everything: Early Initiation of VTE Prophylaxis Following Major Trauma is Effective and Safe. Ann Surg 2025;282:382-388.
15. Guorgui JG, Knowlton LM, Wang S, Arrow K, Knudson MM: Breaking down the evidence: a multicenter analysis of venous thromboembolism among patients with lower extremity fractures. Accepted for publication in 2026 in the J of Orthopedic Trauma.

In addition, there have been numerous presentations from CLOTT at such venues as the WTA, AAST, EAST, Pacific Coast Surgical, Trauma Association of Canada, THOR.  ISTH and ASA