Association of diabetes control on the risk of venous thrombosis: a nested case control study

Date of ISAC Approval: 
27/02/2020
Lay Summary: 
Venous thromboembolism (VTE) is a medical condition in which a blood clot forms in a blood vessel of the leg or other area of the lower body. The blood clot then clogs a blood vessel and thereby causes a deep vein thrombosis (DVT), or the blood clot travels to the lung and causes a pulmonary embolism (PE). The term VTE therefore includes both DVT and PE. VTE is a dangerous, potentially fatal condition. Its prevention and management is of high priority for the National Health Service (NHS). Diabetes mellitus (DM), a disease characterised by high levels of blood sugar over a prolonged period, affects over 450 million patients worldwide (8.8%). Both variants of the disease, DM type 1 and 2, are suspected to be a risk factor for VTE, as it has been observed that VTE occurs more often in individuals with DM. However, to date, few studies have assessed the impact of blood sugar control on the risk of VTE in patients with DM. Additionally, available studies on the topic yielded conflicting results. While some studies found an association between the level of blood sugar control and the risk of VTE, others did not. Our objective is therefore to explore the association between the level of blood sugar control and the risk of VTE in patients with DM type 1 and 2.
Technical Summary: 
Venous thromboembolism (VTE) is a medical condition in which a blood clot (a thrombus) forms in a vein of the leg or pelvis, and either causes a deep vein thrombosis (DVT), or the thrombus travels to the pulmonary arteries and causes a pulmonary embolism (PE). The term VTE therefore includes DVT and PE. VTE is a dangerous condition and an important cause of death. Its prevention and management is a priority for the National Health Service (NHS). Since diabetes type 1 (T1DM) and type 2 (T2DM) affect over 450 million patients worldwide (8.8%), diabetes and its related complications are of great importance for society and the health system. DM is suspected to be a risk factor for VTE as VTE occurs more often in individuals with DM. However, to date, few studies have assessed the impact of blood sugar control (measured as HbA1c levels) on the risk of VTE in patients with DM types 1 and 2. Additionally, available studies on the topic yielded conflicting results. While some studies found an association between the HbA1c level and the risk of VTE, others did not. Our objective is therefore to analyse the association between the HbA1c level (i.e., the primary exposure of our study) and the risk of VTE (i.e., our outcome of interest) separately for patients with DM type 1 and 2. We will perform a nested case-control analysis within a cohort of DM patients using data from the Clinical Practice Research Datalink GOLD. The study period will cover 1995 through 2018. Cases will be T1DM or T2Dm patients who suffered a VTE and we will match 4 controls to each case from the population of patients with T1DM or T2DM, respectively. We will use conditional logistic regression analyses in order to calculate odd ratios with 95% confidence intervals among different HbA1c levels and different medication schemes in cases and controls.
Health Outcomes to be Measured: 
Primary outcome: Venous Thromboembolisms (VTE).
Collaborators: 

Professor Susan Jick - Chief Investigator - BCDSP - Boston Collaborative Drug Surveillance Program
Christoph Meier - Collaborator - University of Basel
Claudia Becker - Collaborator - University of Basel
Sarah Charlier - Corresponding Applicant - University of Basel