Obesity and Health Outcomes

Obesity has become a major public health challenge as cumulative evidence suggests that increased adiposity is a causative risk factor for diverse adverse health outcomes. A recent study suggests that a high body mass index (BMI) causally increases the risk of both heart failure incidence and mortality. The study findings were presented at the AHA Scientific Sessions 2021 and published in the journal Circulation on 8 November 2021.

Obesity can directly impact diseases or syndromes but is also subject to reverse causality, whereby the presence of the disease may influence the BMI. Therefore, researchers of the Copenhagen University Hospital conducted a study to evaluate whether high BMI causally influences heart failure incidence and mortality.

It was an observational and Mendelian randomisation causal, genetic analysis in which researchers studied 106,121 individuals from the Copenhagen General Population Study, 18,407 from the Copenhagen City Heart Study, and 977,323 from publicly available databases.

Key Findings of the Study

Upon observational analyses in the Copenhagen studies with 10 years of median follow-up, the researchers found that the multivariable-adjusted hazard ratios per 1 kg/m² increment of BMI were:

• 1.06 (n=124,528; events=6,589) for heart failure incidence,
• 1.04 (n=124,528; events=1,237) for heart failure mortality, and
• 1.01 (n=124,528; events=24,144) for all-cause mortality.

Upon genetic analyses in the Copenhagen studies, they noted that the age and sex adjusted causal risk ratios per 1 kg/m² increment of BMI were:

• 1.19 (n=118,200; events=6,541) for heart failure incidence,
• 1.27 (n=118,200; events=889) for heart failure mortality, and
• 1.11 (n=118,200; events=16,814) for all-cause mortality.

Combining genetic data from the Copenhagen studies, the Genetic Investigation of ANthropometric Traits (GIANT), the Heart Failure Molecular Epidemiology for Therapeutic Targets (HERMES), and the UK Biobank, they observed that unadjusted causal risk ratios per 1 kg/m² increment of BMI were:

• 1.39 (n=1,095,523; events=53,850) for heart failure incidence,
• 1.18 (n=576,853; events=2,373) for heart failure mortality, and
• 1.02 (n=576,853; events=44,734) for all-cause mortality.

The authors concluded, "High body mass index causally increases the risk of both heart failure incidence and mortality. Obesity should be recognised as a causal factor for development of heart failure, heart failure mortality, and all-cause mortality in treatment guidelines."

For further information: https://www.ahajournals.org/doi/abs/10.1161/circ.144.suppl_1.12326