## 4 Discussion
Findings from our analysis showed that the weight category deviating from the reference weight of 60-80 kg implied up to a 2-fold increase in the risk of all-cause death and numerical increases in CV death. In the unadjusted analysis, the risk of death due to any cause or CV deaths was significantly higher in the lower weight subgroup (\(\leq\)60 kg) versus the reference weight group. Furthermore, the risk of all-cause death appeared to be higher in the lower weight group even after adjustment for eGFR and CHA\({}_{2}\)DS\({}_{2}\)-VASc score. There was a trend of decrease in the risk of death due to any cause and CV deaths in the higher weight groups in the unadjusted analysis. However, the risk appeared to increase with increasing weight after adjustment for eGFR and CHA\({}_{2}\)DS\({}_{2}\)-VASc score. Hence, no obesity paradox was observed in the high weight subgroups in the adjusted analysis. This is contrary to other studies in which obesity paradox was observed, potentially because of differences in the adopted adjustment for risk factors [24; 25]. The vital impact of impaired renal function, as an independent variable, on outcomes in AF, as in many other diseases, explains these findings [26; 27; 28; 29; 30]. Interestingly, patients with lower weight in our analysis appeared to have protection from stroke and bleeding events after adjustment although they had a higher risk of death. These findings point towards optimisation of interventions with the goal to improve the management and outcomes of AF patients, according to the \"ABC\" approach (Atrial fibrillation Better Care [includes A (avoid stroke), B (better symptom control), and C (cardiovascular risk factors and comorbid conditions management)]) developed by European Society of Cardiology [5]. Our analysis was focused on weight categories, which in daily practice are more easily applicable as compared with BMI categories. Indeed, the practitioner usually takes into account body weight for adjusting the dose of NOACs, in combination with assessment of renal function. On the other hand, BMI assessment is largely used in epidemiological studies and is not regularly evaluated in daily practice for baseline patient assessments. The association between BMI and clinical outcomes in patients with AF has been evaluated in various studies but the findings so far have been not concordant. Moreover, some of these studies had incomplete adjustment for confounding factors at baseline and the others were limited by small sample size and retrospective nature of the analyses. Higher BMI and waist circumference were associated with a favourable prognosis (adjusting for comorbidities and treatment allocation) in patients treated with oral anticoagulants [31; 32]. In an analysis of patients treated with edoxaban and warfarin included in the ENGAGE AF-TIMI 48 trial, higher BMI (per 5 kg/m\({}^{2}\) increase) was independently associated with lower risks of stroke/SEE and death, but with increased risk of major bleeding. The effects of edoxaban versus warfarin on stroke/SE, major bleeding, and net clinical outcome were similar across BMI categories ranging from 18.5 to >40 [33]. In a systematic review, an obesity paradox was observed for death due to any cause and CV-related deaths in the analysis of randomised NOAC trials; however, the analysis of the observational studies did not show this relationship. The analysis of the randomised trials also showed an obesity paradox for stroke/SEE and major bleeding, with a treatment effect favouring NOACs versus warfarin that was only significant for normal weight patients. No significant differences were observed between NOACs and warfarin in overweight and obese patients [24]. Some registry data also add to existing conflicting evidence from the randomised trials for the association between BMI and clinical outcomes in AF patients treated with oral anticoagulants. Findings from the DRESDEN registry evaluated the impact of BMIon clinical outcomes in daily care patients treated with NOACs for stroke prevention in AF [34].