What is the clinical evidence from this study?

Study design: Cohort. Population: Atrial fibrillation (n=17913). Intervention: Higher BMI (overweight or obese) and waist circumference vs. Normal BMI. Primary outcome: All-cause mortality (HR 0.63, 95% CI 0.54-0.74, p=< 0.0001).

What does this research mean for the field?

In patients with atrial fibrillation treated with oral anticoagulants, obesity is associated with a significantly lower risk of all-cause mortality compared with normal BMI. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

April 12, 2016Open Access

The ‘obesity paradox’ in atrial fibrillation: observations from the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial

Q: What are the key findings of this study?

In patients with atrial fibrillation treated with oral anticoagulants, obesity was associated with a lower risk of all-cause mortality compared with normal BMI (HR 0.63; 95% CI 0.54-0.74; P<0.0001).

Q: What does this research mean for the field?

In patients with atrial fibrillation treated with oral anticoagulants, obesity is associated with a significantly lower risk of all-cause mortality compared with normal BMI. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Key Result

In patients with atrial fibrillation treated with oral anticoagulants, obesity was associated with a lower risk of all-cause mortality compared with normal BMI (HR 0.63; 95% CI 0.54-0.74; P<0.0001).

Study Design

Type

Cohort (n=17,913)

Structured PICO

Does higher BMI and waist circumference reduce mortality and cardiovascular events in atrial fibrillation patients treated with oral anticoagulation?

Population

17,913 patients with atrial fibrillation treated with oral anticoagulation from the ARISTOTLE trial

Intervention

Higher BMI (overweight or obese) and high waist circumference (>102 cm for men, >88 cm for women)

Comparator

Normal BMI and normal waist circumference

Outcome

Stroke or systemic embolism, a composite endpoint (stroke, systemic embolism, myocardial infarction, or all-cause mortality), all-cause mortality, and major bleedingcomposite

In patients with atrial fibrillation on oral anticoagulation, higher BMI and waist circumference are associated with a lower risk of mortality and cardiovascular events, supporting the existence of an 'obesity paradox'.

Main Result

Effect estimate: HR 0.63 (95% CI 0.54-0.74)

p-value: p=< 0.0001

Abstract

AIMS: The prognostic implication of adiposity on clinical outcomes in atrial fibrillation (AF) patients treated with oral anticoagulation is unclear. METHODS AND RESULTS: ). Waist circumference (WC) was defined as high if >102 cm for men and >88 cm in women. Outcomes were stroke or systemic embolism, a composite endpoint (stroke, systemic embolism, myocardial infarction, or all-cause mortality), all-cause mortality, and major bleeding. Cox models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) across categories of BMI and WC adjusting for established risk factors and treatment allocation. At baseline, 4052 (22.6%) patients had a normal BMI, 6702 (37.4%) were overweight, and 7159 (40.0%) were obese. In multivariable analyses, higher BMI was associated with a lower risk of all-cause mortality overweight: HR 0.67 (95% CI 0.59-0.78); obese: HR 0.63 (95% CI 0.54-0.74), P < 0.0001 and the composite endpoint overweight: HR 0.74 (95% CI 0.65-0.84); obese: HR 0.68 (95% CI 0.60-0.78), P < 0.0001 compared with normal BMI. In women, high WC was associated with a 31% lower risk of all-cause mortality (P = 0.001), 27% lower risk of the composite endpoint (P = 0.001), and 28% lower risk of stroke or systemic embolism (P = 0.048) but not in men. There was no significant association between adiposity and major bleeding. CONCLUSION: In patients with AF treated with oral anticoagulants, higher BMI and WC are associated with a more favourable prognosis.