Venous thromboembolism (VTE), comprising pulmonary embolism (PE) and deep vein thrombosis (DVT), are common and associated with significant morbidity and mortality. VTE risk is higher in chronic inflammatory conditions including inflammatory bowel disease (IBD) and rheumatoid arthritis (RA) compared to the general population. Evidence for differential VTE risk in other inflammatory diseases, notably psoriatic arthritis (PsA) and vasculitis, is more limited. Risk factors for VTE have been described in the general population, but there has been little interrogation of VTE risk factors for individuals with chronic inflammatory conditions and their association with subsequent VTE.
This study aims to describe the prevalence of VTE risk and risk factors in individuals with systemic inflammatory disorders in a contemporary real-world population, by disease type (IBD, RA, and PsA) and relative to a control population without systemic inflammatory disease. In the same cohorts a further comparison will be performed of the influence of VTE risk factors on risk of VTE events in individuals with systemic inflammatory disorders.
A retrospective cohort study will be performed to compare VTE risk and VTE risk factors in adults with IBD, RA, and PsA and matched controls between January 1, 1998 and January 1, 2018, within the Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) network. In the cohorts with and without inflammatory conditions estimate will be determined for the risk of VTE overall, and for PE and DVT separately, using unadjusted Cox proportional hazards models, stratified by matched set (exposed cohort versus unexposed cohort), to provide overall hazard ratios for the association with each outcome. Models will be subsequently adjusted for sociodemographic and clinical and VTE risk factors in multivariable analysis to explore potentially important associations with VTE. The same analyses for each autoimmune condition will be repeated separately. Prespecified sensitivity analyses will be performed to explore the robustness of any potential associations.