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New findings suggest the "obesity paradox" may be explained by rates of exercise among women.
Physical fitness may play a significant role in the “obesity paradox”—the emerging clinical belief that obesity may have protective benefit versus morbidity and mortality among patients with cardiovascular disease, according to new findings.
In a new study presented virtually during the European Society of Cardiology (ESC) 2020 Congress this weekend, a team of US-based investigators showed obese yet physically fit women were 36% less likely to suffer from major adverse cardiovascular events (MACE) than average.
Investigators, led by Odayme Quesada, MD, of the Cedars-Sinai Smidt Heart Institute in Los Angeles, sought to interpret the role of physical fitness—a factor often neglected in studies observing individual body mass index (BMI) and its association with MACE.
As they noted, physical fitness is a known modifier of weight status, and serves as a potential mediator for the effects of obesity on MACE as suggested by the paradox. They investigated the BMI-physical fitness relationship per self-reported Duke Activity Status Index (DASI) scores in participants of the National Heart, Lung, and Blood Institute Women’s Ischemia Syndrome Evaluation (WISE) study.
The multi-center, prospective, cohort WISE analysis enrolled 936 women from 1996-2000 at the time of their clinically-observed coronary angiographies. Patients were assessed for a median follow-up period of 5.8 years for MACE—a composite of death, nonfatal myocardial infarction, stroke, or congestive heart failure.
Quesada and colleagues used proportional hazards regression to estimate adjusted MACE hazard ratios (HRs) among WISE patients as they related to their metabolic status and physical fitness.
High physical fitness was defined as DASI scores ≥25, equivalent to ≥7 metabolic equivalents (METS). Investigators used 899 women with complete data from the trial.
Most (69.5%) observed women had low self-reported physical fitness. Another 34.9% were overweight (BMI ≥25 – 30), and 40.5% were obese (BMI ≥30).
Among women with high physical fitness, HR for MACE was just 0.64 (P = .01). Conversely, women in the normal weight group but with low physical fitness were at a 60% greater risk of MACE (HR, 1.61; P = .01).
As Quesada and colleagues noted, weight status contrived from BMI is limited in clinical understanding; there’s no way to discern contributions to that score from fat versus lean muscle mass.
“Our findings suggest that physical fitness may play a role in the obesity paradox,” they wrote. “These results support the inclusion of fitness in understanding the relations between body weight and long-term MACE.”
Along with concluding that obesity was found to be inversely related with long-term MACE risk among physically fit women, investigated noted DASI scoring is a simplistic tool that better identifies higher-risk symptomatic cardiovascular-risk women. They recommend it be considered in future investigations and even routine examinations of women.
The study, “Role of physical fitness in the obesity paradox. Long-term major adverse cardiovascular events in the Women's Ischemia Syndrome Evaluation (WISE),” was presented at ESC 2020.