Rising Obesity Rates Have Had Similar Impact on Progress Against Cardiovascular Disease and Cancer

Hazel Nichols, PhD

New research from the University of North Carolina suggests the ongoing obesity epidemic has slowed progress against cancer deaths in a manner similar to how it has slowed progress against cardiovascular disease.

An analysis of mortality data from 50 million people within the US over a 20-year period, results indicate progress against cancer deaths has continued in the last decade but this progress, specifically among obesity-related cancers, has experienced a slower annual decline in recent years.

"Obesity is a risk factor for many, but not all, types of cancer," said study senior investigator Hazel Nichols, PhD, an associate professor in the Department of Epidemiology at the UNC Gillings School of Global Public Health, in a statement."We need to make maintaining a healthy weight an obtainable goal for everyone in terms of safe public spaces, availability and affordability of nutritious foods, and other structural factors. The good news in that is if we're able to make these changes as a society, we will be able to improve the health of a nation."

Despite continued advances, many studies indicate improvements in cardiovascular disease mortality in the US began to slow in beginning in 2011 and much of the decline in annual improvements are linked to the growing obesity epidemic. With obesity as a known risk factor for cardiovascular disease and many forms of cancer, investigators designed their analyses as a cross-sectional study of US mortality trends from 1999-2011 and 2011-2018.

Using data from the Centers for Disease Control and Prevention WONDER database, investigators planned to compare trends in cancer and cardiovascular disease-related deaths among all individuals from the database during the aforementioned periods with complete information related to the underlying cause of death, age, sex, race, and ethnicity.

The primary outcome of interest within the study was annual relative rates of change in age-adjusted mortality rates (AAMR) among the overall population and stratified by sex, race, and ethnicity, which was done using Poisson regression. Investigators noted comparisons of AAMR rates of change before and after 2011 were performed using Wald tests.

Using the aforementioned criterion, investigators identified 50,163,483 decedents for inclusion in their analyses. This cohort had a mean age of 72.8 (SD, 18.5) years, 50.1% were female, 79.9% were non-Hispanic White decedents, and 11.7% were non-Hispanic Black decedents.

In 1999, cancer or cardiovascular disease represented 53.6% of total deaths and this figure declined to 44.4% in 2018. When assessing cancer-related mortality, results indicated total cancer mortality improvements experienced greater accelerations from 2011-2018 (annual AAMR relative change, -1.77; 95% CI, -1.67 to -1.86) than 1999-2011 (annual AAMR relative change, -1.48; 95% CI, -1.43 to -1.52) (P <.001).

Further analysis pointed to a similar trend when assessing decreases in mortality for cancers not associated with obesity in 1999-2011 and 2011-2018. However, when assessing obesity-related cancer mortality, results indicated mortality decline began to slow after 2011, with an annual AAMR relative change of -1.19 (95% CI, -1.13 to -1.26) from 1999-2011 compared to -0.83 (95% CI, -0.70 to -0.96) from 2011-2018 (P <.001).

Investigators noted the largest decelerations observed in their analyses took place among female decedents (-1.45 [95% CI, -1.36 to -1.53] in 1999-2011 and -0.91 [95% CI, -0.75 to -1.07] in 2011-2018; P <.001) and non-Hispanic White individuals (-1.16 [95% CI, -1.09 to -1.22] in 1999-2011 and -0.68 [95% CI, -0.55 to -0.81] in 2011-2018; P <.001).

This study, “Comparison of 20-Year Obesity-Associated Cancer Mortality Trends with Heart Disease Mortality Trends in the US,” was published in JAMA Network Open.