Impact of body mass index on mortality and hospitalisation of patients with atrial fibrillation

Association between obesity and statin use on mortality and hospital encounters in atrial fibrillation

Background

Obesity increases risk of atrial fibrillation (AF) at least in part due to pro-inflammatory effects, but has been paradoxically associated with improved mortality. Although statins have pleiotropic anti-inflammatory properties, their interaction with obesity and clinical outcomes in AF is unknown. We explored the relationship between BMI, statin use, and all-cause mortality and AF/congestive heart failure (CHF)-related encounters, hypothesizing that statin exposure may be differentially associated with improved outcomes in overweight/obesity.

Methods

This was a single center retrospective cohort study of adults with AF diagnosed between 2011-2018. Patients were grouped by body mass index (BMI) and statin use at time of AF diagnosis. Outcomes included all-cause mortality and ED or inpatient encounters for AF or CHF.

Results and Conclusions

A total of 2503 subjects were included (median age 66 years, 43.4 % female, median BMI 29.8 kg/m2, 54.6 % on baseline statin therapy). Increasing BMI was associated with decreased mortality hazard but not associated with AF/CHF encounter risk. Adjusting for statin-BMI interaction, demographics, and cardiovascular comorbidities, overweight non-statin users experienced improved mortality (adjusted hazard ratio [aHR] 0.55, 95 % CI 0.35-0.84) compared to statin users (aHR 0.98, 95 % CI 0.69-1.40; interaction P-value = 0.013). Mortality hazard was consistently lower in obese non-statin users than in statin users, however interaction was insignificant. No significant BMI-statin interactions were observed in AF/CHF encounter risk. In summary, statin use was not differentially associated with improved mortality or hospitalization risk in overweight/obese groups. These findings do not support statins for secondary prevention of adverse outcomes based on overweight/obesity status alone.

Practices, beliefs, and attitudes of clinicians in prescribing direct oral anticoagulants for obese adults with atrial fibrillation: a qualitative study

BACKGROUND

Atrial fibrillation (AF) and obesity affect over 60 and 650 million people, respectively.

AIM

This study aimed to explore clinician practices, beliefs, and attitudes towards the use of direct oral anticoagulants (DOACs) in obese adults (BMI ≥ 30 kg/m²) with AF.

METHOD

Semi-structured interviews via video conference were conducted with multidisciplinary clinicians from across Australia, with expertise in DOAC use in adults with AF. Clinicians were invited to participate using purposive and snowball sampling techniques. Data were analysed in NVIVO using thematic analysis.

RESULTS

Fifteen clinicians including cardiologists (n = 5), hospital and academic pharmacists (n = 5), general practitioners (n = 2), a haematologist, a neurologist and a clinical pharmacologist participated. Interviews were on average 31 ± 9 min. Key themes identified were: Health system factors in decision-making Disparities between rural and metropolitan geographic areas, availability of health services, and time limitations for in-patient decision-making, were described; Condition-related factors in decision-making Clinicians questioned the significance of obesity as part of decision-making due to the practical limitations of dose modification, and the rarity of the extremely obese cohort; Decision-making in the context of uncertainty Clinicians reported limited availability, reliability and awareness of primary evidence including limited guidance from clinical guidelines for DOAC use in obesity.

CONCLUSION

This study highlights the complexity of decision-making for clinicians, due to the limited availability, reliability and awareness of evidence, the intrinsic complexity of the obese cohort and limited guidance from clinical guidelines. This highlights the urgent need for contemporary research to improve the quality of evidence to guide informed shared decision-making.

Association Between Body Mass Index and All-Cause Mortality in a Prospective Cohort of Southern Chinese Adults Without Morbid Obesity

Objective: This prospective study examined the relationship between body mass index (BMI) and all-cause mortality in Chinese adults without morbid obesity.

Methods: We prospectively examined the relationship between BMI and all-cause mortality in 12,608 Southern Chinese adults with age ≥35 years who participated in the National Key R&D Program from 2013–2014 to 2019–2020. Cox proportional hazards models were used to examine the association between BMI and all-cause mortality.

Results: The prevalence of being underweight, normal weight, overweight and having moderate obesity was 7.36%, 55.83%, 28.51% and 8.31%, respectively. A total of 683 (5.65%) deaths occurred during a median follow-up period of 5.61 years. The Cox proportional hazards models indicated that a continuous BMI level was negatively associated with all-cause mortality [adjusted-hazard ratio (HR) per 1 kg/m² increase: 0.96, 95% CI 0.93 to 0.98, p < 0.001]. Furthermore, the HRs of all-cause mortality in the underweight, overweight and moderate obesity groups were 1.31 (1.05, 1.64), 0.89 (0.73, 1.08) and 0.64 (0.44, 0.92), respectively in the confounder model relative to the normal weight group. Survival analysis further confirmed this inverse association of the four BMI categories with mortality.

Conclusion: BMI was negatively associated with all-cause mortality in southern Chinese adults without morbid obesity. Compared to the normal weight category, adults in the moderate obesity category had lower all-cause mortality, whereas being underweight was associated with increased all-cause mortality.

Obesity Paradox in Atrial Fibrillation: Implications for Outcomes and Relationship with Oral Anticoagulant Drugs

In the last 40 years, concern about the obesity epidemic has increased. Data from the current literature highlight a strong relationship between obesity and atrial fibrillation (AF), particularly in relation to an increased risk for incident and recurrent AF. A phenomenon called the "obesity paradox" has emerged: the apparently counterintuitive evidence from epidemiological data indicating that overweight and obese patients may have a better prognosis than healthy-weight patients. A differential impact of oral anticoagulants (OACs) in terms of effectiveness and safety in the various body mass index categories has been postulated, particularly in the comparison between non-vitamin-K antagonist oral anticoagulants and vitamin K antagonists. This review aims to summarize the evidence on the impact of obesity in patients with AF, focusing on descriptions of the obesity paradox and its relationships with OAC treatment.

The obesity paradox for outcomes in atrial fibrillation: Evidence from an exposure-effect analysis of prospective studies

The impact of obesity on the prognosis of atrial fibrillation (AF) remains controversial. We conducted an exposure-effect meta-analysis of prospective studies to clarify the relationship between body mass index (BMI) and outcomes in patients with AF. The Cochrane Library, PubMed, and Embase databases were searched through May 1, 2019. Summary relative risks (RRs) were calculated using random-effects models. Nonlinear associations were explored using restricted cubic spline models. Twenty publications involving 161,922 individuals were included. Categorical variable analysis showed that underweight was associated with an increased risk of all-cause mortality (RR: 2.6), cardiovascular death (RR: 2.91), major bleeding (RR: 1.57), stroke or systemic embolism (RR: 1.62), and a composite endpoint (RR: 2.23). In exposure-effect analysis, the risk per 5 BMI increase was reduced for adverse outcomes (RR=0.86, 95% CI: 0.80-0.92 for all-cause death; RR=0.82, 95% CI: 0.71-0.95 for cardiovascular death; RR=0.89, 95% CI: 0.84-0.95 for stroke or systemic embolism; and RR=0.78, 95% CI: 0.67-0.92 for a composite endpoint). There was a significant "U"-shaped exposure-effect relationship with all-cause death, and the nadir of the curve was observed at a BMI of approximately 28. Our results showed that underweight is associated with a worse prognosis, but that overweight and obesity are associated with improved adverse outcomes in patients with AF.