Subjective Theory of Illness and Disease Perception in Patients with Unprovoked Venous Thromboembolism – The Qualitative Dalí Study

Introduction Venous thromboembolism (VTE), comprising deep vein thrombosis (DVT) and pulmonary embolism (PE), is a common cardiovascular disease associated with significant morbidity due to acute symptoms and long-term complications. In patients without identifiable risk factors, i.e., unprovoked VTE, long-term anticoagulation therapy is often recommended to prevent recurrent events. Adherence to anticoagulant therapy might be influenced by the disease perception of patients with unprovoked VTE, a currently understudied topic. Therefore, we aimed to understand disease perception, including the subjective theory of illness, in patients with unprovoked VTE. Method We conducted a qualitative study encompassing semi-structured interviews of patients with unprovoked VTE three to twelve months from diagnosis who received a medical recommendation for long-term anticoagulation. A purposive sampling strategy with an underlying sampling frame was used to maximize range of views and experience. Patients were asked about VTE diagnosis, self-perceived reasons for VTE, attitude towards anticoagulation, and changes in daily life. Interviews were audio-recorded and transcribed verbatim. Thematic analysis according to Braun and Clarke using the MAXQDA software was performed to identify common themes. Results From November 2024 to March 2025, we interviewed 22 patients with unprovoked VTE (mean interview duration: 26 minutes), including 10 (45.5%) women and 10 (45.5%) patients with an age below 50 years ([ Fig. 1 ]). Self-perceived reasons for unprovoked VTE included psychological stress; lifestyle (including obesity, smoking, physical inactivity); family history; events prior to VTE; and personal overload/overexertion, among others. We identified the following common themes: (1) lack of understanding and dissatisfaction with unidentifiable reason for VTE, self-blame, and inadequate explanation; (2) dissatisfaction with therapeutic possibilities, including wish for alternative options, fear of long-term consequences, and logistic burden of anticoagulant therapy; and (3) realization of mortality and changes in lifestyle. Fig. 1 Clinical characteristics of included patients Conclusion Despite the lack of identifiable clinical reasons for a thrombotic event in patients with unprovoked VTE, patients themselves expressed various subjective theories of illness. Further, we identified several common themes which are important to affected patients. These subjective theories of illness and patient-relevant themes might influence adherence to anticoagulation and should therefore be openly discussed with patients to be incorporated into shared decision-making. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany