Risk of Death from COVID-19 Among Obese Higher for Men, Younger Adults

August 20, 2020

Patients with severe obesity are 4-times as likely to die from COVID-19, a new study finds, with younger patients and men with obesity at highest risk.

Patients with severe obesity are 4-times as likely to die from COVID-19, according to findings published in the Annals of Internal Medicine.

The results, reported by a team of researchers from Kaiser Permanente, expose a "striking association" between BMI and risk for death that is independent of obesity-related comorbidities and other potential confounders.

The data also suggest that the risk of death from COVID-19 among patients with obesity is not uniform across populations, disproportionately affecting men and younger adults, aged <60 years.

“Although this study examines a variety of factors that may be associated with risk of death from COVID-19, our main objective in this paper was to understand risk related to obesity, and obesity-associated chronic conditions in our health care system,” said lead researcher, Sara Y. Tartof, PhD, MPH, of Kaiser Permanente Southern California Department of Research & Evaluation, in a Kaiser Permanente press release.

The Kaiser team examined electronic health care records of nearly 7000 Kaiser Permanente Southern California members who tested positive for COVID-19 between February 13 and May 2, 2020. Mean age was 49 years and mean BMI, 30.5. A BMI of 30 to 39 is considered obese, 40 to 44 is severely obese, and 45 or higher is extremely obese.

BMI, Age, Sex

For the highest BMI measures, the adjusted incidence rate of death was 7.08 (95% CI, 3.58 to 14.00) per 100 patients, corresponding to an attributable excess of 5.52 (CI, 0.63 to 10.42) deaths per 100 patients when compared with the incidence rate estimate for BMI of 18.5 to 24 kg/m2.

When BMI was modeled as a continuous variable, a nonlinear risk relationship was detected (P = 0.005). A strongly monotonic increased risk for death was seen as age increased. Men had higher risk for death than women. Comorbidities with elevated risk in adjusted analyses included prior myocardial infarction, prior organ transplant, and hyperlipidemia. Progression in time was strongly associated with decreased risk for death over the study period.

Age-stratified analysis found a substantially higher risk of death among those with severe and extreme obesity aged ≤60 years vs the overall model. Among patients aged ≥61 years, the association between BMI and death was attenuated, observed only for the highest measures. In the older patients, increasing age escalated in importance, with a 127% increased risk for death per decade.

In analysis stratified for sex, high BMI was associated with substantial risk for death in men, with risk estimates above those in the overall model. Women had no increased risk for death associated with BMI. In both age- and sex-stratified analyses, increasing calendar time significantly decreased risk for death.

The researchers were able to control for a variety of risks previously reported in the literature and did not detect increased risk of death from COVID-19 associated with Black or Latinx race/ethnicity alone.

“Our finding that severe obesity, particularly among younger patients, eclipses the mortality risk posed by other obesity-related conditions, such as history of myocardial infarction, diabetes, hypertension, or hyperlipidemia, suggests a significant pathophysiologic link between excess adiposity and severe COVID-19 illness.”

“By viewing the risk posed by obesity through the prism of COVID-19, this study advances the characterization of obesity as a disease that demands a public health and clinical response similar to that for diabetes or heart disease,” said Sameer B. Murali, MD, an internal medicine physician at Kaiser Permanente Fontana Medical Center and senior author on this study.

“One pandemic is expanding our understanding of another, and we hope this work not only provides physicians and patients a better grasp of the risk obesity poses in the setting of COVID19, but also to overall health.”


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