Cohort Profile: The Danish Venous Thromboembolism Cohort - A Linkage Between Danish National Health Surveys and Health Registers.

Introduction: Venous thromboembolism (VTE) is a common disease with a serious prognosis. Nonetheless, many aspects of this multicausal disease are poorly understood. The aim of establishing The Danish Venous Thromboembolism Cohort was to study VTE risk and prognosis within a life-course context.

Methods: The Danish Venous Thromboembolism Cohort was based on respondents to the questionnaire-based Danish National Health Survey (DNHS) conducted in 2010, 2013, and 2017 and was linked to Danish national health and administrative registries.

Results: A total of 474,022 unique respondents to the DNHS were included in this cohort, 8,460 of whom were diagnosed with VTE before the survey response date. The survey's response rate varied between 54% and 60%. The median age at the survey response date was 54 years (interquartile range: 40-66 years), and 46.1% of respondents were men. The cohort contains detailed information on lifestyle factors (smoking habits, alcohol consumption, physical activity level, and dietary habits), health status indicators (healthcare-seeking behavior, body mass index, self-rated health, and mental distress), and self-reported morbidities. In addition, the survey data were linked to records in Danish medical and administrative registries to obtain information on clinical data and outcomes, including hospitalizations, medication use, laboratory test results, labor market participation, vital status, and causes of death.

Discussion: The Danish Venous Thromboembolism Cohort is a valuable data resource for use in future studies on VTE research, with a focus on risk factors, complications, interactions, and prognosis.