The venous thrombosis registry in Østfold Hospital (TROLL registry) ‐ design and cohort description

PURPOSE: The incidence of venous thromboembolism (VTE) is expected to increase over the next decades, further increasing its substantial impact on patients and health care resources. Registries have the benefit of reporting real‐world data without excluding clinically important subgroups. Our aim was to describe a Norwegian VTE registry and to provide descriptive data on the population and management. REGISTRY POPULATION: The Venous Thrombosis Registry in Østfold Hospital (TROLL) is an ongoing registry of consecutive patients diagnosed with, treated, and/or followed up for VTE at Østfold Hospital, Norway, since 2005. Baseline and follow‐up data, including demographics, clinical features, risk factors, diagnostic procedures, classification of VTE, and treatment were collected during hospitalization, and at scheduled outpatient visits. FINDINGS TO DATE: From January 2005 to June 2021, 5037 patients were eligible for research in TROLL. Median age was 67 years (interquartile range, 55–77), and 2622 (52.1%) were male. Of these, 2736 (54.3%) had pulmonary embolism (PE), 2034 (40.4%) had deep vein thrombosis (DVT), and 265 (5.3%) had upper‐extremity DVT or splanchnic or cerebral sinus vein thrombosis. In total, 2330 (46.3%) were classified as unprovoked VTE, and 1131 (22.5%) had cancer. Direct oral anticoagulants were the most frequent therapeutic agents (39.3%) followed by low‐molecular‐weight heparins (30.4%) and vitamin K antagonists (30.3%). Outpatient treatment for PE increased from 4% in 2005 to 23% in 2019. FUTURE PLANS: TROLL is a population‐based ongoing registry that represents a valuable source of real‐world data that will be used for future research on the management and outcomes of VTE.