Author + information
Several studies have investigated the impact of body mass index (BMI) on the prognosis of atrial fibrillation (AF), but the results remain controversial. We therefore aimed to estimate the association between BMI and stroke/systemic embolism (SE), all-cause death and cardiovascular death in patients with AF through a systematic review and meta-analysis of published studies.
We systematically searched the Cochrane Library, PubMed, and Elsevier databases through May 2016 for all studies reporting the association between BMI and adverse outcomes in AF patients. BMI was assessed as a categorical variable according to the standard World Health Organization definition. Risk ratios [RRs] and 95% confidence interval [CIs] were abstracted and then pooled by a random-effects model.
A total of 10 cohort studies, which comprised 51,586 participants, were included in this meta-analysis. Among patients with AF, underweight was associated with increased risks for stroke/SE (RR = 1.96, 95% CI 1.32 - 2.90), all-cause death (RR = 2.61, 95% CI 2.21 - 3.0) and cardiovascular death (RR = 2.49, 95% CI 1.38 - 4.50). However, the pooled RR values in the overweight patients were lower than that in the normal weight patients for cardiovascular death.stroke/SE (RR = 0.91, 95% CI 0.80 - 1.04), all-cause death (RR = 0.76, 95% CI 0.63 - 0.93) and cardiovascular death (RR=0.69, 95% CI 0.48 - 0.99), respectively. Obese was associated with decreased risks for stroke/SE (RR = 0.84, 95% CI 0.72 - 0.98), all-cause death (RR = 0.80, 95% CI 0.62 - 1.02) and cardiovascular death (RR=0.87, 95% CI 0.66 - 1.15). We further categorized obese BMI into 3 stages: I (≥30 to < 35 kg/m2), II (35 to < 40 kg/m2), and III (extremely obesity ≥ 40 kg/m2) and found the relationship between higher BMI and lower risks of AF-related outcomes remained unchanged.
In summary, our meta-analysis demonstrates that underweight is associated with increased risks for stroke/SE, cardiovascular death and all-cause death, while overweight even obese are associated with the decreased risks in AF patients. Our cumulative meta-analysis is first to document the existence of the “obesity paradox” in AF patients.