5035Elevated blood pressure and risk of venous thromboembolism: evidence from 6.6 million UK adults

Abstract

Background/Introduction: Elevated blood pressure (BP) is a major risk factor for a range of arterial vascular events. However, its association with the risk of venous thromboembolism (VTE) is not well understood. Prior studies have typically been of limited size or duration to able to assess modest but important associations. Purpose: To investigate the association between systolic blood pressure (SBP) and diastolic blood pressure (DBP) with the risk of VTE. Methods: We used the UK Clinical Practice Research Datalink (CPRD), a population-based prospective cohort data which is contains data from 674 general practitioners in the UK covering approximately 7% of the current UK population. A total of 6,613,644 people aged 30 and 90 years with at least one blood pressure measurement were included. Usual SBP per 20 mmHg increase, usual DBP per 10 mmHg increase and hypertension (SBP >140, DBP >90) were considered as exposures. VTE defined as pulmonary embolism (PE) or deep vein thrombosis (DVT) was considered as the main outcome. Cox proportional hazard model was used to estimate multivariate-adjusted hazard ratio (HR) with floating absolute risks. Results: Of the 5,588,280 people that met the inclusion criteria, 104,017 (1.9%) were diagnosed with incident of VTE. Overall, each 20 mmHg higher SBP and each 10 mmHg higher DBP were associated with a 20% and a 17% lower risk of VTE during a median of 9.6 years of follow-up (HR: 0.80; 95% confidence interval [CI] 0.79 to 0.81; and HR: 0.83; C: 0.81 to 0.84), respectively. Hypertension was associated with an 18% lower risk of VTE incidence was (adjusted HR 0.82; CI 0.81 to 0.84). The strength of the association per 20 mmHg higher SBP and 10 mmHg DBP declined with increasing age categories. Proportional differences were broadly similar between men and women for SBP (P for interaction = 0.31). Conclusions: With over 100,000 incident VTE events, we were able to investigate the impact of elevated BP across its whole spectrum and found that higher BP is associated with lower risk of VTE. The observed associations were stronger among younger patient groups. Meta-analysis of blood pressure lowering trial could potentially investigate the causal role of low BP on future risk of VTE.