Cardiovascular risks and bleeding with non-vitamin K antagonist oral anticoagulant versus warfarin in patients with type 2 diabetes: a tapered matching cohort study

BACKGROUND: We compared the risk of bleeding and cardiovascular disease (CVD) events between non-vitamin K antagonist oral anticoagulant (NOAC) and warfarin in people with type 2 diabetes (T2DM). METHODS: 862 Incident NOAC users and 626 incident warfarin users with T2DM were identified from within 40 UK general practice (1/4/2017-30/9/2018). Outcomes included incident hospitalisation for bleeding, CVD and re-hospitalisation for CVD within 12 months since first anticoagulant prescription, identified from linked hospitalisation data. A tapered matching method was applied to form comparison cohorts: coarsened exact matching restricted the comparison to areas of sufficient overlap in missingness and characteristics: (i) demographic characteristics; (ii) clinical measurements; (iii) prior bleeding and CVD history; (iv) prescriptions with bleeding; (v) anti-hypertensive treatment(s); (vi) anti-diabetes treatment(s). Entropy balancing sequentially balanced NOAC and warfarin users on their distribution of (i-vi). Weighted logistic regression modelling estimated outcome odds ratios (ORs), using entropy balancing weights from steps i-vi. RESULTS: The 12-month ORs of bleeding with NOAC (n = 582) vs matched/balanced warfarin (n = 486) were 1.93 (95% confidence interval 0.97-3.84), 2.14 (1.03-4.44), 2.31 (1.10-4.85), 2.42 (1.14-5.14), 2.41 (1.12-5.18), and 2.51 (1.17-5.38) through steps i-vi. ORs for CVD re-hospitalisation was increased with NOAC treatment through steps i-vi: 2.21 (1.04-4.68), 2.13 (1.01-4.52), 2.47 (1.08-5.62), 2.46 (1.02-5.94), 2.51 (1.01-6.20), and 2.66 (1.02-6.94). CONCLUSIONS: Incident NOAC use among T2DM is associated with increased risk of bleeding hospitalisation and CVD re-hospitalisation compared with incident warfarin use. For T2DM, caution is required in prescribing NOACs as first anticoagulant treatment. Further large-scale replication studies in external datasets are warranted.