Two-year outcomes of UK patients newly diagnosed with atrial fibrillation: findings from the prospective observational cohort study GARFIELD-AF

Abstract

Background: The outcomes of patients newly diagnosed with atrial fibrillation (AF) following the introduction of direct-acting oral anticoagulants are not well known.

Aim: To determine the 2-year outcomes of patients newly diagnosed with AF, and the effectiveness of oral anticoagulants in everyday practice.

Design and setting: This was a prospective observational cohort study in UK primary care.

Method: In total, 3574 patients aged ≥18 years with a new AF diagnosis were enrolled. A propensity score was applied using an overlap weighting scheme to obtain unbiased estimates of the treatment effect of anticoagulation versus no anticoagulation on the occurrence of death, non-haemorrhagic stroke/systemic embolism, and major bleeding within 2 years of diagnosis.

Results: Overall, 65.8% received anticoagulant therapy, 20.8% received an antiplatelet only, and 13.4% received neither. During the study period, the overall incidence rates of all-cause mortality, non-haemorrhagic stroke/systemic embolism, and major bleeding were 4.15 (95% confidence interval [CI] = 3.69 to 4.65), 1.45 (95% CI = 1.19 to 1.77), and 1.21 (95% CI = 0.97 to 1.50) per 100 person-years, respectively. Anticoagulation treatment compared with no anticoagulation treatment was associated with significantly lower all-cause mortality adjusted hazard ratio (aHR) 0.70 (95% CI = 0.53 to 0.93), significantly lower risk of non-haemorrhagic stroke/systemic embolism (aHR 0.39, 95% CI = 0.24 to 0.62), and a non-significant higher risk of major bleeding (aHR 1.31, 95% CI = 0.77 to 2.24).

Conclusion: The data support a benefit of anticoagulation in reducing stroke and death, without an increased risk of a major bleed in patients with new-onset AF. Anticoagulation treatment in patients at high risk of stroke who are not receiving anticoagulation may further improve outcomes.

Keywords: all-cause mortality; anticoagulation; atrial fibrillation; bleeding; stroke.

Figure 1.

a) Treatment at diagnosis by CHA₂DS₂-VASc score. b) Treatment at diagnosis by HAS-BLED score. AP = antiplatelet. DTI + AP = direct thrombin inhibitor and antiplatelet. FXa + AP = factor Xa inhibitor and antiplatelet. VKA + AP = vitamin K antagonist and antiplatelet.

Figure 1.

a) Treatment at diagnosis by CHA₂DS₂-VASc score. b) Treatment at diagnosis by HAS-BLED score. AP = antiplatelet. DTI + AP = direct thrombin inhibitor and antiplatelet. FXa + AP = factor Xa inhibitor and antiplatelet. VKA + AP = vitamin K antagonist and antiplatelet.

Figure 2.

a) Event rates according to CHA₂DS₂-VASc score. Includes only patients with available CHA₂DS₂-VASc scores (n = 3528). b) Event rates according to HAS-BLED scores. Includes only patients with available HAS-BLED scores (n = 2530). SE = systemic embolism.

Figure 2.

a) Event rates according to CHA₂DS₂-VASc score. Includes only patients with available CHA₂DS₂-VASc scores (n = 3528). b) Event rates according to HAS-BLED scores. Includes only patients with available HAS-BLED scores (n = 2530). SE = systemic embolism.

Figure 3.

Unadjusted and adjusted hazard ratios of OAC versus no OAC (reference) and corresponding 95% confidence intervals for selected outcomes at 2 years of follow-up in UK patients. Adjusted hazard ratios were obtained using an overlap-weighted Cox model. Variables included in the weighting scheme are: cohort enrolment, sex, age, ethnicity, type of AF, care setting specialty and location, congestive heart failure, acute coronary syndromes, vascular disease, carotid occlusive disease, prior stroke/transient ischaemic attack/SE, prior bleeding, venous thromboembolism, hypertension, hypercholesterolemia, diabetes, cirrhosis, moderate-to-severe chronic kidney disease, dementia, hyperthyroidism, hypothyroidism, current smoking, heavy alcohol consumption, body mass index, heart rate, systolic and diastolic blood pressure at diagnosis, and baseline antiplatelet use. AF = atrial fibrillation. OAC = oral anticoagulant. SE = systemic embolism.