Characteristics, Treatments, and Outcomes of Venous Thromboembolism in Young Adults Aged 21-40 years: Individual-Patient Meta-Analysis of Randomized Clinical Trials

Venous thromboembolism (VTE) is a condition in which blood clots form in the veins. It includes deep vein thrombosis (DVT), where a clot forms in a deep vein (usually in the leg), and pulmonary embolism (PE), where a clot travels to the lungs and can be life-threatening. VTE affects both adults and younger people, but most research to date has focused on older adults. Although some studies have included or focused upon patients under 21 years old, very few have examined those aged 21 to 40 years. As a result, little is known about how VTE develops, how it is treated, and what outcomes occur in this younger adult group.

We will address this important gap by analyzing existing data from completed randomized clinical trials of VTE treatments in adults. These data are available through public data-sharing platforms such as Vivli and the National Heart, Lung, and Blood Institute (NHLBI) BioLINCC repository. Our research will focus on the subgroup of participants aged 21 to 40 years within these trials.

We will combine individual participant data from multiple trials into a single analysis, called a meta-analysis. This will allow us to study patterns that may have been undetectable in individual trials where the number of patients in the 21-40 age group may have been too small.

Specifically, we will:
1. Describe the demographic (e.g., age, sex) and disease features of young adults with VTE, including details of their treatment (type and duration of anticoagulant therapy—medications that prevent blood clots) and their clinical outcomes, such as recurrence of VTE, bleeding events, and long-term complications like post-thrombotic syndrome ((PTS) leg pain or swelling after a clot).
2. Compare these features and outcomes between young adults (21–40 years) and older adults (>40 years) who took part in the same clinical trials.
3. Identify factors that may predict which young adults are more likely to experience certain outcomes, such as recurrence of VTE or bleeding.

By studying this age group in detail, we will provide valuable information for doctors and researchers about how VTE behaves in younger adults. Our findings will help design future clinical trials focused specifically on this population, improving understanding of how to tailor treatments and follow-up care to meet their needs.